Dan: hello there, welcome
back to the Quantum Divide.

This week I'm joined by
Natalia Herrera Valencia.

I would think that there is a roll of the
R there, but I'm not going to attempt it

because I'm a monosyllabic Englishman.

So Natalia is a postdoc at Heriot Watt
working in the group of Mehul Malik.

Some highlights for the show are, I
get confused by spatial entanglement.

I, we have a Honestly, total
coincidence which really made me

chuckle about my phone wallpaper and
the cover of nature physics magazine.

We talk about hyper entanglement and
encoding information into multiple

dimensions, believe it or not.

Then we talk a little bit about industry
readiness and polish off with Ben Nevis.

Hopefully that's got you interested
enough to listen through.

Enjoy.

. Thank you very much for
joining us, Natalia.

Why don't you introduce
yourself first of all?

How did you get to where you are today?

forward to our conversation
about the kind of projects

you've been working on and so on.

Natalia: Thank you so
much for having me then.

So yeah, just I'm
Natalia Herrera Valencia.

And I'm a Colombian physicist that ended
up in Edinburgh for some reason currently

working at Heriot Watt University.

I'm a postdoc yeah, a research
associate there in the group where

I also did my PhD, the Beyond Binary
Quantum Information Laboratory.

And it's been a journey of,
yeah, maybe 10 years and uh,

quantum That has led me here.

Everything started from my university
in Colombia where I was doing my

undergrad in physics in the National
University of Colombia to promote

the best university in the country.

My alma mater.

I love it.

Yeah, It's great to, to push it there.

And so yeah, if you, I can tell you
a bit how I ended up at Hayward.

Cause first I was I was an undergrad
that was really excited about physics

and thought that I was going to be
a theorist for the rest of my life.

And that changed very quickly when
I actually started doing physics.

So in my fourth year, I have in
Columbia, we do five years of undergrad.

Like we take a lot of courses
is very long, but it paid off.

And I think in the third, fourth year,
I was having a existential crisis about

maybe I don't like physics because
I wasn't finding the passion in it.

And then I realized that What I wasn't
finding passion was in theory and

that I needed to move to experiment.

And yeah, just one thing led to
another opportunities that allow

me to do some internships in Mexico
with actual experimental physics.

And I got into quantum optics there and
then a conference that inspired me, led

me to the photonics field and led me
to apply to an Erasmus Mundus program.

In photonics, which is a really cool
masters because it allows you to be in

Europe, but in different universities,
that's why it's their asthma speed.

So I ended up applying it and
yeah, getting a scholarship for it.

And then move to France in Marseille
did some photonics courses there.

Then I did an internship in Vienna
and the Institute of quantum

optics and quantum information.

That's where I'm at.

Who is my current boss, Mehul Malek.

At the moment, he was a postdoc,
and we worked in the lab together.

And, it just clicked there.

But then I had to finish my master's,
so I had to go to Barcelona and got

amazing people teaching me everything
about quantum because you have everybody

from ICFO and University of Barcelona,
the Autónoma, Politécnica de Cataluña,

all together giving this master's.

That was a bit crazy.

And then I did my math, my master's
thesis at the Max Planck of Quantum

Optics in Garching in Munich.

Garching.

It's not really Munich you'll
find out that when you move there.

And yeah, and that was just all over.

And after traveling all over
Europe, I was ready to settle down.

So Mehul decided that he was going
to start a group in Edinburgh in

an university called Heriot Watt,
which I've never heard before.

But he seemed convinced that was the
best place to, to start his group.

And I said, sure.

And I moved in, I moved and
I started the group with him.

I was his first PhD
student and that was 2019.

So that's, and that's how
I started up in Edinburgh.

And we started the group and now
we're probably like 10 people now.

And it's been a great ride.

Dan: You have had

Some amazing adventures
on your academic journey.

I can tell, I can tell, especially
on that Erasmus course, moving around

and experiencing different cultures
and universities and teaching methods.

And that's really good kind of um, you
must have a really well rounded kind

of understanding of quantum academia
in Europe as a whole, do you think?

Okay.

Natalia: To, if they have the chance
and if they have the privileges, I had

to go and work in different groups.

It's fantastic because you
really understand, yeah.

not only different cultures, but
different ways of working and

just living in different spaces.

It just inspires you.

Such a big international community.

It was wonderful.

It can take a toll though.

I must say, like I was, it
was very heavy two years.

And after that, I like all of my
exploration, Sense died out and I

was like, please leave me alone.

I don't want to move.

Just want to settle for a few years.

That's why I've been in Edinburgh,
I'm planning to stay for a while

here, because it takes a toll on you.

But it was mad, I had the opportunity
to fulfill all of my, those dreams

of, when you're in the global south
in a place like in Latin America, we

only hear about these groups if your
professors talk about maybe someone that

inspired them, or a paper they read.

Maybe they also did, Some postgrad in
Europe and they have some collaborators,

but you always see it so far away.

An idealized world.

And I remember my professor telling me
when he first visited the Max Planck, he

told me, they, they have a basement and
it's just eight optical tables all over.

It's huge.

And I just couldn't imagine that.

And I was like, Oh, it would be really
cool to be in a place like this.

So it was crazy to when, when I was just
like looking for a place to do internships

on my master's thesis, that the master
allowed me to just like, And I would

just send emails and say, can I work
with you in this institute that, I won't

tell you, but I've been dreaming about.

And they were like, yes, of course.

Come and come.

We have a position.

You can work here for a few months.

And it's just fulfilling
dreams through this.

So it's it was very lucky.

Inspiring.

Dan: It's very, actually,
funny to hear you.

I think it's probably the first time
I've heard somebody say that they'd

be happy working in a basement.

As long as you've got some optical

Natalia: Yes.

Dan: to play with.

Doesn't sound like a very
nice environment, but

Natalia: we're weird.

You have we have to accept us as
it says, we like especially optics,

basements or black darkness, but
it's the dream if you have space.

Dan: Excellent.

Okay.

Yeah.

One of the misconception that I
had was that Harriet Watt is an

Edinburgh University and I understand
now that it's a separate university

and I can relate this to my student
years when I went to Nottingham.

I didn't go to Nottingham Trent.

Same kind of setup, I guess.

I don't know about the about the
leadership and everything, though.

I'm sure they're totally separate
in Nottingham and probably

the same in Edinburgh as well.

So is there any is there competition?

Is there good collaboration in the
physics departments and things?

What would you say?

Natalia: I think there's always this idea.

Obviously Edinburgh Uni has.

such a big reputation in history, right?

So I think we always see it
as like that big university.

We know some people there.

The beauty of Harry Watt is that it
was born out of kind of dream precisely

of what, of having something that was
a bit more applied And so it started,

yeah, just like more a technical
university and it has grown now.

but we're kind of new
compared to Edinburgh Uni.

And I think what pull us, like at least
Mehul, and now I'm convinced that it

was a great choice, what put us there
is that The photonics and quantum

science department at Harriot Watt is
just fantastic and it's something that

Edinburgh Uni doesn't really have.

Edinburgh Uni is really strong in
other parts of physics but if you want

to look at experimental photonics and
quantum science really it's Harriot Watt

who's really strong and in that sense
we will be closer to Glasgow Uni or to

Strathclyde where we also have fantastic.

photonic groups and groups
working also in quantum science.

So I think that as for as an experimental
physicist in photonics, Harriot Watt

is, it's just a great way because
we have a lot of space, very big

labs, and I think they also really
like to encourage young researchers.

So you have a community there in the
department that you have experienced

researchers, but you also have a lot of
young groups coming in and those young

groups have the same opportunity having
a lot of lab space and students, which

sometimes, you know, with the politics in
the UK in the universities, you realize

that you cannot take that for granted.

So yeah, I'm glad that
he made the right choice.

And we have just On in the whole fantastic
groups to work in photonics and quantum.

Dan: Very nice.

Yeah let's get into the
technology a bit then.

Why don't you start with your PhD project?

Because that's something that you've
closed, in the last year at some point.

That's a big milestone.

Natalia: Yes.

The biggest milestone in my life.

Dan: yeah give us a walkthrough
of what the project was and what

your research activities were.

What you loved, what you really
had some challenges with or issues

with, or things that you felt that
you needed to work on, et cetera.

Natalia: It was a very particular
PhD because I arrived and I was a

first student and there was a lab,
but there was nothing in the lab.

So it was a challenge, but
at the same time, fantastic.

experience that I was
able to build the lab.

So it's the beyond binary
quantum information laboratory.

So my PhD was pretty much working on all
the projects that the group wanted to do.

And at the moment, the
group was the two of us.

So we wanted to explore the possibility
that and the capability of light of

encoding information beyond just binary
encodings, but working on the spatial

degree of freedom and probably in
the temporal degree of freedom too.

Mehul had some experience
from that in Vienna.

We had even worked together when I was
in my internship and that was my first.

familiarity with the spatial encoding.

So we came to Harry Watt
to continue that work.

And it was my PhD could have been
summarized as building a platform for

generating, manipulating and transporting
high dimensional states of light.

And in particular in the
spatial degree of freedom.

So it was, it entailed everything
about building entanglement sources,

that you can exploit spatial
entanglement with, tailoring the

way that you generate and measure.

these photons so you can have really
high dimensionalities and high quality

entanglement, figure out a way how
to transport and distribute this

type of entanglement, and then also
figure out platforms to manipulate it.

Because when you go to a degree of
freedom that is no polarization, you

pretty much, you don't have the tools.

There's no, you just, in polarization
you have a beam splitter, polarized beam

splitters, wave plates, fibers, support.

The both degrees both polarizations.

So when you move to space, you have none
of those, we don't have any multi port,

we don't have a spatial beam splitter.

You don't have, if you want to transport
it through fiber, you have mode mixing

So it was a PhD about tackling all of
these challenges and even exploiting some

of the disadvantages that you could see,
for example, in, in multimode fibers,

which are complex media and seeing the,
this mode mixing actually as a tool

that we could harness to build platforms
for a spatial a spatial photonic state.

So that was pretty much the PhD.

everything that I did since I was a first
student and kind of being extended and now

the whole group has been continuing this.

So you know the next PhD student
focused more on, we already had the

sources and the way to generate them
and tailor it, so he focused on the

study of how they could be noise robust.

And the advantages we could
have, so we work on that.

And then, for example, the
next PhD student was more on

the manipulating the states.

But that was a project
I was also involved in.

And now we're moving to the time
degree of freedom, for example.

And so that was very exciting.

And at the end of my PhD, I wanted to
just go the next level and say, okay,

we had two photons entangled in space.

Now I'm going to work with
multiple photons and try to

manipulate them in space.

That was the end of my PhD,
the last chapter of the thesis.

But then taking into account, I
decided I started my PhD in 2019.

Which mean I did half of
my PhD during the pandemic.

Which was a challenge

Dan: locked in a basement
with a mask on, I

imagine, in a hazmat suit.

Natalia: In a hazmat suit and a not,
not interacting, being used to always

having this fantastic feedback between
the group, because by then we, by 2020, we

were already like five or six and we were
very used to working together and just.

And then when you go, you realize that
even though it's experimental physics

and just going from nine to five
alone to the lab is not productive,

because you, any problem you have if
you cannot discuss it with people like

right there, then it's not productive.

It could take weeks and it could be
the silliest thing that you could have

solved by just turning and saying, behind
Hey, do you know how could I do this?

So I think that was a, that was the
worst bit of working during that time

that we couldn't really have the group,
the exchange of ideas, the discussion

just like a lot of frustration.

But.

Lucky enough, we were also able
to be very productive through it.

I'm very glad.

We had the advantage that they let us
in the university pretty early on, just

after one month or one month and a half.

We still were able to, get our work
done, get enough things for the

PhD students, all of us to feel
that we didn't need to extend it.

More than the four years that we were
going to make so So yeah, it wasn't

terrible, but it was very frustrating
I think that was one of the biggest

challenges and obviously the trauma
that they were was left with after the

pandemic, we all realize we survive it.

And maybe I don't know, a year after I
realized I had deep traumas with it or

something, like my life had completely
changed and I hadn't noticed and I

was dealing with it a year after.

so

Dan: right, So you've got PTSD from
being in the lab too much for this

Natalia: I, yeah, something like that,
just you realize like it just affects

your brain and not talking to people.

So

Dan: Okay, I've got a question.

So you mentioned spatial
modes of entanglement.

When I first started learning
about entanglement and its use in,

um, kind of commercial products
it's fairly limited set out there.

all use polarization
from what I can gather.

Now there, I've now discovered
that there's entanglement sources

on, on the market which have
degrees of freedom using time.

So that's like the superposition
between early and late is the way

that I've done the calculations.

And then there's The degrees
of freedom within frequency.

So like different colors, is that the
spatial type or is spatial mode different

because I don't think I've heard that

Natalia: Yes, spatial mode is different.

I think the reason why m There's more
familiarity with the time and frequency,

especially for communication is,
these degrees of freedom are fantastic

for long distance communications.

There's a lot of challenges, however,
on trying to use more than two of those.

The way that you have to do measurements,
coherent measurements is a big challenge.

And so if you want to do anything
related with entanglement in this degree

of freedoms, there's It's a lot of
people have lots of PhDs based on this,

precisely, and we have lots of work to do.

So the spatial degree of freedom, you can
see it more as, um, the transverse spatial

profile of light when it propagates.

These beautiful modes that you, when
you study the wave equation, and

you say that the wave equation in
cylindrical coordinates or in a Cartesian

Coordinates they will be supported
and you have the Laguerre Gauss modes,

you have the Hermite Gauss modes.

You can just decompose your solution
of propagation in a spatial basis and

it's this shape of light and in theory,
the when photons are generated through

spontaneous parametric down conversion,
because of momentum conservation, you have

pretty much entanglement over an infinite.

dimension in space, right?

Because the state is made
out of this superposition of

all of these spatial modes.

Now, in reality, it's not infinite
because crystals are not infinite

and apertures are not infinite.

So you have a bandwidth.

But when we talk about the spatial degree
of freedom is this shape of light, this

way that it propagates and its profile
that looks like different shapes.

And In that sense, it could be scaled
also to very high dimensions like time.

And we've developed a lot of tools to
be able to measure this properly and to

transport it and to manipulate it with
fantastic devices like spatial line

modulators, which have changed the game
completely in, in spatial manipulation.

So yeah that's what I mean
with spatial degree of freedom.

Dan: I think I'm still struggling.

So I'm going to ask a couple of

silly questions probably.

You know, You often see a picture
of a photon represented as traveling

at different orthogonal kind
of modes to each other, right?

As a, it's a wave, which has a, it has
a a direction obviously in a wavelength.

And I can understand the time
and the wavelength changing.

Then in terms of the shape, we're
talking here about wave packets, which

are emitted emitted deterministically,
or perhaps spontaneously, yeah,

depending on the equipment you're using.

Could you describe the shape a bit more?

I don't think I've got
that right in my head.

Natalia: Yeah, I think it's easier
to, when you imagine like the, think

of the wave particle duality, because
I think it's easier when you go to

waves propagating in space and then
you have, yeah, they're propagating

over let's say generally the z axis,
so that's the longitudinal, right?

And then you have the x y plane
where the wave will be oscillating

and if you are in a cavity.

Which some geometrical restrictions your
wave propagation is going to be, let's

say, it's only going to be supported
over a few modes of in that X, Y plane.

So the different modes that light could
have when it propagating across, for

example, a cylinder those modes, the
way that they look in X, Y, if you make

that cut that those modes have a shape.

And that's the solution.

Those are the solutions that you have.

For example, if you were to have been
cylindrical coordinates, and you do

this equation, you solve the equation,
you will see that one of the solutions

will be the Laguerre Gauss mode.

So you have what we like
to call the fusilli.

Imagine a fusilli, like light
having that shape of rotating and

orbital angular momentum on it.

So that's, for example, one of one
of the shapes that you can easily

imagine because orbital angular
momentum is a bit more common.

And then you think, okay, those
are waves and and now photons are,

light is a wave and it's a particle.

And then photon turns out also has a
wave function that will be described

in space and will have, a probability
over this XY plane of propagation.

And it turns out that it's not just,
a point, it has, yeah, a distribution

over this x, y, and depending on how
your light is being generated and

which medium is propagating in you'll
be able to have different modes of

this photon that will be supported.

And yeah, so imagine photons propagating
as fusilli past us, for example

rotating in different directions.

And if you were going to cut
and just see it, on a picture,

you will see them in rings.

For example, or just yet beautiful
rings or superpositions of

these modes that look just mad.

But then you can also think of it as
it has a distribution, so you could

imagine to decompose it in a basis
that looks like the pixels of a camera.

And then you have a basis that looks
as pixels and you could expand it.

explain and you can write your
your density your wave density as

these modes, as these pixel modes.

So it's it's a bit strange to think
about it as photons because you're

like photons they're a particle.

And what do you mean they have a
distribution in space and yeah and it's

so strange, but then you're like waves.

They're also wave, light is wave, and
photons will also have that behavior.

And then because if we're talking about
a wave function, and when you're like,

okay, I could write a wave function in
x, y, z, and then if you look at x, y,

oh, solutions that could be different
modes of light, and then you're like,

oh, maybe a photon can have shapes.

So yeah that's, I hope
maybe that's clearer.

Dan: It is.

It's almost like I feel like I need
to see all the different shapes and it

reminds me of a cover of a there's a
cover of nature that I really liked.

It was, I can't remember who the
paper was or whatever, but it had

all these pictures of, maybe they
were excited states or something.

But it had all these different
shapes, and I just thought, Eh,

it's a bit like that, maybe.

Natalia: it's like that.

Actually, now that you're talking about
covers just to promote ourselves, if

you actually looked at the the cover
of Nature Physics from November 2020.

It was volume 16, number 11.

And that's when we that's the, yeah,
the edition where we publish my first

PhD paper, which is called on scrambling
entanglement through a complex medium.

Dan: I can't believe this, but that's
exactly the, I've just found it.

that's the

picture I'm talking

Natalia: Yes I thought that when you
were I was like, this looks a lot like,

so that cover was the work of our post
doc because, we were very excited when

they say, if you have a, if you have a
baby, you can suggest a cover and we were

thinking we have a spatial modes let's
try to do something beautiful with it.

And then you have Sarosh was
just, this artist that said, Oh,

I show the moats of the fiber.

That's important.

Maybe do like a pattern with it
and we send it and it just looks so

beautiful and I'm so proud of it.

So that's our cover.

That's

Dan: That was that was my um, my
phone wallpaper for about six months.

Natalia: Oh, I'm

Dan: that's actually really funny.

That is such a funny coincidence.

Um, I couldn't remember if they were
photons or atomic structures, but yeah.

Natalia: When you said it, I was like,

maybe it's ours.

Dan: yeah, that's exactly the one.

So they are very beautiful
to look at actually.

Natalia: they're absolutely beautiful.

In particular, so these modes are the
type of spatial modes that you have

propagating inside a multimode fiber.

So they are all of these mix and
they all mix in between them.

So when you, yeah, when you excite a
multimode fiber and you start bending it.

You could be start seeing these
type of patterns a bit more speckly.

And these are, yeah, these are
decomposing in the Garry Gaussian basis.

So you have these beautiful radial and
azimuthal structures that are great

for covers and putting on your phone

and your profile pictures.

Yeah, no I always upload those.

It's great for our posters too.

Dan: Right, So tell me, what's the
benefit of this mode of entanglement, or

this mode of superposition, if you like,
between the different spatial modes?

Um, is there a physical benefit
or a mathematical benefit?

What's, how does that look?

Natalia: Yeah what I always put
this as a slide on my presentation

is like, why bother with this?

And so we're looking at
quantum applications, right?

Photons are ideal carriers of
information, so we're generally

looking at it as applications
of communication, for example.

So when you are able to encode in
multiple dimensions, so let's talk

first like about advantages of why
bother with high dimensionalities.

So you know, the kind of more
straightforward The other thing to look

at is where you have more capacity, right?

Because you don't have just series on
ones, but you have a fuller alphabet.

So you have the possibility of just one
photon encoding lots of more information.

Then it turns out that when you
have different levels in which your

information are encoding, it turns out
that gives you also noise robustness.

So it means that if you are working
in a higher dimensional space.

And for example, you have entanglement
over these different levels, you will

be able to support more noise and or
even more loss when you are distributing

that entanglement than if you were
just working with binary encodings.

And it goes from this
series like information is

spread over different modes.

So even if you lose some, there's still
You still have something valuable there.

The resource is still there.

And we've been able to demonstrate
that beyond just the theory and seeing

that indeed when you have, for example,
entanglement, and if you were trying

to certify that you're in your state
is entangled, let's say over some

conditions of loss and noise, if you
are able to encode this information in

a higher dimensional space, it makes
you way more robust, and you can stand.

just very high levels of loss if
your fidelity is really high, or

if, or a lot of levels of noise,
if your loss is loss, right?

And then it's a balance, of course.

And as more bigger the dimensionality
you find more noise robustness and

more, or more loss robustness too.

So loss resistance, so
that's, those, to our

Kind of the, the advantages
in communication.

So, and we push push it a lot of
why even bother with this now.

A lot of people are, but
that's high dimensional.

So you could say you could
have that in time too.

But and there's a lot of work
and we were also pushing that

because time will be fantastic.

You transporting time
being encodings is easier.

Infrastructure is ready for it.

You don't need multimode fibers or
you do not, you don't need multicore

or some type of multiplexing
in spatial degree of freedom.

It's just, you'll be able to send
it through a single mode fiber

and just being able to measure it.

But then that's when the challenge
comes because it's not only about

detecting, let's say in space,
you will have a camera, right?

And if you're able to have a
camera and you detect single

photon, resolving camera, you're
like, oh, I can detect space.

Or if you have a really good,
time resolution detector, single

photon detector, you're able to
have the early, the late, the

latest, the earliest, and yeah.

But when you're trying to, when
you're trying to build superposition

states and then measure these
coherent superpositions of multiple

modes, That's when it gets tricky.

So in time the way to do it pretty much
is you have to delay one and the other

and delayed with a lot of interferometers
and they made them arrive at the same

time with these in this coherent way.

So it will be, if you want to increase
dimension, you just have to add.

And add interferometers in able to for it.

So if you're able to measure these
and then control this and being

able to control the face over all
of these interferometers, so you

can actually control the coherent
superposition or you don't lose that.

That's.

That's challenging in scaling
and we're trying to work.

We have our way to work that
out and hopefully we'll have

some results soon to show.

But the beauty of space in that
sense is that we do have tools that

allow you to just measure everything.

any arbitrary superposition.

And there's a caveat, there's any
arbitrariness, like how good you are

at measuring this is what my PhD was.

It's sometimes the resolution of your
SLM may not be great or the way that

you measure it later, but it's all about
how you do these projective measurements

in coherent modes the superposition
modes, that's where the challenge is.

And when you're dealing with
entanglement, this is very important.

So in summary, high dim, stronger, better,
prettier and then space for now, this is

one that we really know how to measure.

And we and we're working on how
to transport it and manipulate it.

Dan: So when you said, first of
all multidimensional, I was, I

thought, okay, so you're doing some
kind of encoding in space and time

together but it doesn't sound like.

Natalia: You can, do that.

Dan: You

can, but you're not.

Yeah.

Sounds very complex and, delicate.

Natalia: Figuring out ways to
simultaneously measure in space,

time, polarization, and coherently.

And that's big.

Big challenge because we don't
have like there's no device

that allows you to do that.

So you have to come up ways to
with the devices that you have

to perform these measurements.

And to preserve the coherence between it.

Because if you were just going to
measure Maybe just single photons

or just wave packets or attenuated
laser then if it's just about

encoding and decoding, it's easier.

But if you're dealing with entanglement
yeah, it's a different ballpark.

Yeah, there's a, you could have photons
encoding in space and time, like

that you have entanglement in space
and time and you could harness it.

because you can measure
it and manipulate it.

But that's it.

For my PhD, for example, was purely
focused on, we're just going to use

the the space degree of freedom we
engineer our sources, so there's actually

very high purity, so they don't have
any frequency, or mode entanglement.

And that way we don't have any
hyper entangled states, but

then you can do the opposite.

There's people that work on the
frequency and the temporal degree

of freedom and they do the opposite.

So they have this really high,
large spread in frequency, but then

they they put it in cavities or Or
single mode fibers and you just kill

all of the spatial entanglement.

And, but yeah it's all about, you
know, you can go higher and higher

with the overcoming these challenges
by building the right tools.

To do it.

And then even if you something I wanted
to comment is it's not only communication,

it's the spatial degree of freedom opens
and the manipulation of quantum states

in the spatial degree of freedom is
also useful when you're trying to think

about sensing or, Even computation,
multiplexing is becoming so relevant.

For example, in the sensing space
or bioimaging right, there's a lot

of work already on, and biophotonics
that is using spatial degrees

of freedom for manipulation and
imaging and sensing and then trying

to use quantum light for imaging
has, seems to have some advantages.

So it's also really important to develop
the tools to be able to manipulate and to

measure this type of states, not only for
communications, but also opening this door

to applications in imaging and sensing.

And then In the computation one now
we know that photonics is a fantastic

platform for computing, and I hope
now the world is convinced of this.

And now if you think about the, if
we want to build scalable computing

platforms, they will have to be
looking at multiplexing and switching.

And this is a really big challenge.

And You could be doing this in time,
you could be doing this in space.

You can also think of, for
example, in a chip, the space

one becomes more of a path.

That's what they call like path degree
of freedom, similar to spatial modes.

So it's just, it opens all of these new
doors of applications and boosting the

performance of quantum applications.

Or that's what I like to

Dan: well It's your job to, yeah
or at least investigate it.

I was, I hadn't heard the phrase
hyperentanglement before and

it's just totally blown my mind.

I guess I'm thinking about, you mentioned
entanglement in time and space and

I'm thinking could those things, are
they mutually exclusive or, could

you have a pair of photons which are.

Entangled in space, but
not time and vice versa.

Or is it always an, it's the
entanglement always entangled.

Natalia: So photons, they live in
space and time and polarization.

So they always have
something there, right?

It's all about, really, The way you're
creating these photons or you're

propagating these photons, you what we
call like trace over, so if you ignore

this or you you're not measuring it,
you're like tracing over this, and

you're post selecting your photons.

So you only looking at
particular degrees of freedom.

The states I have, for example they
could be if the states I have, I mean,

spontaneous parametric down conversion.

And for people that are not familiar
with it, just think about, it's a laser,

you're hitting a nonlinear crystal,
nonlinearity interaction is great.

And you just, one photon gets annihilated.

It generates two, two pairs of photons,
and this is a parametric process,

means it conservates energy, momentum.

So these pairs of photons have really
particular properties, and they're like

twins And if you look at energy, and
if you, or if you look at momentum,

then you will have correlations there.

And that's where entanglement comes out.

The mesh photons come out and if
you want to state, write the state

in space, like the spatial bit of
it, you have your entanglement on it.

Now, you could also Figure out, say
that's product tensor product with

whatever is in time and frequency.

And you would want that
to be a tensor product.

Because that would mean this,
you're separable in that sense.

And so if you're tracing over it,
you're still have a, an entangle, a pure

entangle state and not a mixed state.

So the way that we make sure that
this is separable is by the way that

we engineer the sources and just
looking at monochromatic sources

are not super high bandwidth.

So you control the pump.

You also controlled really up
to what bandwidth you can see.

And this is all the way
I'm moving my hands.

listeners wouldn't do, but it's because
I'm imagining the plots of what we

call these joint spectral densities
or joint spatial densities and is

this Four dimensional functions in
space and time and they're all like

multiplied by each other and they
look like long correlated stuff or

just points if you want separable.

So it's all about engineering on your
state so you can ignore degrees of

freedom if you want to ignore them.

Then you could have states that will
have correlations in space and time.

And then if you're able to
measure them that's great.

If you're not, then your
state is not useful.

So it's not That one kills the other
like they're all living there together,

but it's about engineering it.

So is there separable
so you can be useful.

And if they're not that you're
able to do coherent measurements

over this simultaneously over
these joint degrees of freedom.

So your resource is still
there and it's useful.

so, you know, Your photons photons
are doing everything at the same

time, but we ignore the rest and then

Dan: it, got it.

Yeah.

Fascinating.

Okay.

I feel like I need to go away
and read your PhD thesis now.

Natalia: That you will
be like the fifth person.

Great.

Dan: Fifth person to read it.

Yeah.

Natalia: That.

Dan: so let's move on.

We were going to talk about
your project that you've got

going on called intertangle.

Tell us a bit about that.

What's the goal of it.

And Yeah, give us a bit of an
idea of the value proposition,

what your goals are, etc.

Natalia: Yes.

So this project started as us trying to
think, okay, we have been working a lot on

research in the way that we are generating
disentanglement and tools, and this is

the moment where quantum technologies is.

Finally, coming to the point of
we're seeing real applications

and real companies coming out
there and engineer, giving us

real products, engineer products.

And, I think every researcher that
is in the quantum field now, we're

starting thinking, huh, could we be
looking at applied, more applied stuff?

Is there, is there any value
there that we could be having?

I was also in the middle of my crisis of
a postdoc of what have, what am I going

to do with my life now after the PhD?

What can I do?

Do I just go to academia or
if I go to industry, but I

really like what I'm doing.

I started talking with with my,
with Mehul and like collaborators.

That we have and thinking,
Okay, let's see if there's some

commercialization path there.

Is there a value in entanglement?

Is there a value in multiplexing?

And so that's where Intertangle was born.

So I was lucky to, get get selected for
a ICURE program, which is an Innovate

UK program that allows researchers to
leave the lab and talk to real people.

Because we, by real people mean
like not us but like people that

actually are doing stuff and trying
to ask them, what are your problems?

Can I solve them?

Can I have something to offer?

And so we have well, I identified
through this process that now in

the field of quantum technologies,
we are in a very emerging market.

Wonderful things are happening, but
still a lot to go in development,

integration, interoperability, when
we're talking about quantum technologies

and communications, quantum computing,
and when I was talking to all of these

industries, I realized that everybody
needed in their quantum journey, either

now or later, they needed entanglement.

Entanglement is a resource, it's a
capability that you want to have.

If you're looking at communications,
you're looking at computing, even

if you're looking at sensing,
it's a valuable capability.

All of the Companies that are
looking at you harnessing quantum for

boosting capabilities, for boosting
capacities there are looking at it.

And.

And that's what, when we identified,
we may have something useful because

we can offer this capability that is
entanglement, photonic entanglement,

and we know we're experts on it.

And so we thought, okay, what can we do?

So we like to put it as intertangle is
about putting entanglement in a box.

It's a box that you don't have to then
go and figure out complicated equipment

and or have PhD people or quantum experts
to be able to control the systems.

But, it's accessible, user friendly
hardware that we want to develop that

will deliver very good entanglement
and will also deliver tools to measure

and to manipulate entanglement.

So we're thinking of just moving
to that phase of when lasers were

created and there were years where
people were just building, everybody

was building their own laser to,
to do whatever they wanted to do.

And then finally put people start put
those lasers in a box and they will

be reliable, easy to use and everybody
could just Ship them and have a laser

in their lab and start concentrating
of using the laser as an application

for the particular application.

We want to move quantum technologies
to that phase when you're not really

worrying about how to generate or
create or manipulate entangled sources

or entangled photons, but you want
to use them and you can just do that.

And you don't need to be a
quantum physicist for it.

This is also an important
thing that I realized.

Because now quantum technologies
is moving to a field that you're

going to be dealing with telecoms
infrastructure, with data centers.

You want to integrate
computers into, to networks.

And The people that actually understand
these infrastructure are not quantum

physicists, they're telecom engineers,
they're like, they have software people,

you have hardware people, and they
obviously Nobody wants to have to learn

all the ETPT of quantum, they want
something reliable systems that you can

put in and you say, look, this is going
to help you do this, you just turn it on

and you have it and you can measure it and
you don't need to understand what a photon

is and what a joint spectral density
is or what quantum state tomography

is or entanglement certification
or blah, blah, blah, blah, blah.

So we, we're trying to see with
this project if there is a path in

commercialization of these type of
tools, entanglement in a box, call

it intertangle, unbox the future of
quantum, accessible in everybody's hands.

And, and I think there's
the, there's a lot.

We identified through this that
there is definitely a value in this,

especially in the stage of the quantum
technology industry, that is such a

development industry at this moment.

We are, we like to say that we're ready,
for, to sell on their systems there,

but many times when you go and you talk
with the whole ecosystem, there's yes,

we want to build a quantum network.

And we're ready to go.

But we don't really know why the quantum
internet will be used yet, and but

let's build it because we need to start
because we, this will take some time

and we need to test it and integrate it.

But then we also, yeah, don't know
how it works and if it will be useful.

So it's still like a lot of these
discussions on but in all of this, we're

like, the important thing is to have
tools that will make this testing and

this integration and this figuring out.

so we want to get in there
and provide these tools.

Dan: Okay.

So the question I've got is
I'm hearing that you've spoken

People in different industries
and explore different use cases.

And I know, depending on the document
you're reading, you can get this whole

plethora of different use cases for
entanglement, or you can just get

one or two and there are companies
out there focusing on particular.

Topologies I'll say.

So you've got like the data center,
you've got the wide area network,

each has its own potential, different
use cases I've seen in, there

are products out there, which.

Like you're describing you
turn them on and off you go.

There are other products in kind of
the data center space where there's

a real integrated approach with the
quantum computing systems or sensors

that are using them, and perhaps
that kind of flick a switch and

turn it on, wouldn't really work.

So I guess what in your research
of the different industries.

Which use cases have you hooked
into, don't list them all, but give

me one or two where you think this
product that I'm envisaging would be

perfect for this particular use case.

Natalia: Yeah, it's that you, I
think you pointed out like the two.

two, The two places in particular.

So we realized that right now, because
of the way that the industry is

working, really what we need to be
working at is network providers, right?

No not the people that maybe will be
wanting to get the security, let's say

banks or you have like an insurance
company or train, but we're talking

to the network provider that wants
to be able to give this capability

and put it into their system.

So we, for example, have
an, a collaboration with BT.

Because we want to start
integrating entanglement into

their networks, both like intercity
level and data center level.

So we develop, we want
to develop these boxes.

So you can put first to integrate
like to see, let's say if we were

just entanglement in polarization
or maybe time for communications.

So that you can go in and connect
to your infrastructure fibers, fiber

network, and you can send your photons
and you can use it for, let's say, QKD

or entanglement based QKD that on the,
on secure communications, but, so that

will be, network providers that want to
provide this type of security and codings,

and we've seen that their clients who
are also financial services or even maybe

some defense or maybe some governmental
clients would like to have that.

But They are the ones who have to
integrate and we are working with them

to understand precisely these needs.

Now there, there's another one, which
the, as you mentioned, the data centers,

and this is something we've been working.

I've been talking, for example, with
Elham Kashifi, the co founder of

VeriCloud and chief leader scientist
in the National Quantum Computing

because Elham understands that the
value In quantum information processing

is not only QKD, it's not only about
security, it's computing, but it's not

only QKD, there's a plethora of quantum
protocols that could give, could be

useful for different applications.

And they all not necessarily long distance
communications, but they, she envisions

a lot of data center and a short distance
architectures and by working with the,

with her and hopefully National Computer
Computing Center, we want to be able to

build these, what you were calling more
integrated kind of adaptable systems.

That will be working in for data center
for either building distributed quantum

computing or trying to do some kind of
distributed, let's say, blind quantum

computing protocols, or just other types
of security protocols are short distance.

So we were working with in both
sides is really R& D level.

that we'll be providing these tools
because we need to first be on that stage

before really going to any end user.

So I think, yeah, this just to make sure
that this works, this can be integrated

and make the R& D people life easier so
they can really see that the potential of

this and not just blinded on maybe we can
only do, Photons for QKD and that's it,

which is still pretty good, but because
things can be hard or just, it's hard to

go forward if you don't have the right
tools or the right partnerships, then they

just stay, everything stays on the same.

application

level.

Dan: feels like it's, yeah, it
feels like there's a little bit

of chicken and egg going on.

Because The way you described it
there, you're distributing this

entanglement and then you've got
the end user, but actually it's not

that straightforward at all, right?

The entanglement is a resource and it's a
very, it's a very, can I say short lived,

um, very fast, uh,

brittle, delicate resource.

You need to have something
that's consuming it.

So when you say the end user I'm
actually thinking, what is the

device that goes on the end of,
on, on the end of this network?

That's where I see the chicken
and egg in that there aren't many

computing vendors that are looking
at Utilizing photonic entanglement.

There are some very interesting
experiments with atom light like

iron traps, emitting photons and
then interacting in the network.

And so on.

but when it comes to the actual end
user equipment, so in the traditional

IT space, we call it the CPE, for
example, the customer premises equipment.

That's the.

That's really lacking.

And that could be a number
of different things.

It could be some forms
of distributed sensing.

It could just be a memory, which acts as
a buffer to something else, or it could

be a computer or a computer with memory.

Um, I think of the

main,

Natalia: Or a switch

Dan: yeah.

We're in the loosest term, right?

Cause you, you can't switch like you
can in the traditional world where

you look at a header and decide where
you're going to send it unless you end

up with a very unique hybrid switching.

Technology approach.

I guess what I'm trying to say is what
are you doing about the end nodes?

Are you in some of these use cases,
are you working with QKD providers?

Are you working with memory providers?

Are you making your own memories?

Natalia: yeah, no, I think, um,
we realized that is that opens a

whole can of worms on the sense of
eventually, you know, in on a roadmap.

, if we're looking at communications,
everybody wants to have a memory.

, So I would never say we're not going to
be looking at memories because I think

there's a lot of potential in the teams
that we work with and our collaborators

that could be happening at one point.

At this moment we're not
looking at something like that.

I would say more in the end user case
what we could provide is let's say

yeah you're distributing your source
your photons and then the end user is

going to receive them but detecting
entanglement there's a caveat on how

you detect your entanglement, right?

And how you measure it and keep it useful.

In polarization, yeah, you have fiber
and then polarize beam splitter and

you have two detectors and that's it.

Or maybe some wave plates.

If you were to have time or a space,
this becomes completely different.

And we all shouldn't understand.

How to overcome these challenges.

So let's say like our products would
be these modular hardware of, you have

a source, but you also have what you
call your measurement or detection

box that allows you to do this
coherent measurements of entanglement.

And also we know how to, what measurements
to perform so that you can understand

the resource and the state that you have.

This quantum state that you have in,
quantum states are hard to characterize.

It's a complicated bit, especially
if you have high dimensional systems.

It means a lot of measurements, a lot of
theoretical tools to make these efficient

and to get the right information.

So we want to, built also a software
layer or software tool that will be okay.

We have, we can able to detect, but
we also know what measurements to

do and how to make them really fast.

You know what you have.

And that will be given to you.

And so it's not just like, Oh, you know,
we give you the source and you figure out

if it's useful or not, but it's also the
box that tells you, this is what you have,

this is what, how can you monitor it?

Or even if you were to
use, for example, another.

Because I can imagine that network
providers won't have one type of

entanglement source or from one single
company, they probably will have do

you have different type of sources
or entanglement or even memories that

you have quantum states from different
providers and you need a box that

will be able to tell you the green
and red of if the resource is being

useful or not, is working, is not.

Inside your data center,
outside distributed to end user.

And that's another one of our,
let's say, entanglement in a box.

It's not only about the generation, but
it's about the characterization of this

resource and of this quantum state.

And that's something that
we will also want to build.

So I guess that's what we will
be giving on the end user side.

It's the measurement,
and fast, green, red.

Yeah, entanglement, no entanglement.

In a simple way,

instead

of

Dan: thumbs up and thumbs down,
which obviously the listeners

can't get on the podcast,

Natalia: love it.

Yeah, it's just a, because

imagine, oh yeah, you.

Dan: as well.

Natalia: Yeah, it's it's just imagine
somebody tells you, oh yeah, you

have a fidelity of blah, blah, blah.

And a heralding rate of this
and what does that mean?

Like if an engineer is there and wants to
figure out if the link was broken or not.

So we need to start
translating this to useful.

Dan: Let me describe that in my own words.

So you've got a central source, which is
in the network somewhere, which is then

distributing the photons across two links.

I'm just thinking of a basic forget
about a network for the time being.

It's just a left and right arm and
then with a sensor on each end which

is then measuring the photons is
there a are you looking for the.

Distribution across different Bell states
is that, and then reporting on that.

Okay.

And could, do you get all four?

It might be a stupid question.

Of course you probably do get all four
Bell states in the spatial entanglement.

Natalia: Yeah.

Bell be states are two
dimensional encoding.

So you can, , generally write in h and v.

Let's say you name H zero and V one.

And then you can

just,

Dan: is a record store, isn't it?

Natalia: Yeah.

So you know

Dan: Sorry.

Horizontal and vertical.

Natalia: call.

Yes, exactly.

Sorry.

This is what I'm telling you.

We need to go outside and talk
to people, instead of just

outside, not just inside the lab.

So you bell.

Many people would be either familiar
with horizontal vertical, or maybe

they've been, they've seen it written
in forms of zeros and ones, and you have

these different types of superposition.

So in the spatial degree of
freedom, you can have just two

modes, and have zeros and ones.

Like just in name one, zero and
one, and you can build a bell state.

There is something called like
generalized bell states, because when

you go to high dimensional like this,
it's like a zoo of state, right?

And then you have you have these new bases
and kind of the generalized Bell states

of trying to figure out what is a high
dimensional maximally entangled state.

And then in the bipartite case, like
they see two parties, two, two photons,

that's also easy to say, you just know
that is the one that has written as kind

of superposition of, let's say, 1 to d.

And then you have two photons, so
like 0, 0, plus 1, 1, plus 2, 2, dd,

all of them with the same weight.

That's a maximally entangled state.

But then you will have, you could have
different ways of, with different phases.

So it's, it's a bit more
than just the Bell state.

Let's say what we always say
is, we're trying to aim to have

the maximally entangled state.

That's the maximally entangled state.

You, you can have and so that,
that would be the equivalent and

this then the source indeed trying
to do what we want to generate.

So is the closest thing to that and
then to be able to operate on it and

rotate it as you will be doing when you
rotate from Bell State to the other.

Or even more important, not even
from one Bell State to the other,

but rotation between bases.

You, if you have horizontal, vertical,
and then you just have a wave plate,

and you have diagonal, anti diagonal.

And then you can do measurements also in
that, when you're talking with spatial

degrees of freedoms or temporal degrees of
freedoms, these rotations are, imagine,

yeah, just trying to figure out a rotation
in space and time for a, what a basis

is, and then you have to think, oh,
it's like, it looks like a superposition

of these other states, and it just
gets a bit your head it's a headache.

Dan: Your nose starts
bleeding at that point,

Natalia: yeah, exactly.

And it's Oh, and then they're orthogonal
and you have all these beautiful, I like

to just see them because in space they can
start looking just shinier and crazier.

When you build this kind of
orthogonal basis, we call it

this mutually unbiased basis.

Which is how you call the
sets of horizontal, vertical,

anti diagonal, left and right.

Circular, these are mutually unbiased
bases and then we build those in space,

and we want to build them also in time.

So it's a whole thing of when you
start multiplexing, it's not only

just detecting, and detecting it
well, it's, How do you measure

all these very complicated things?

So if you ever want to boost whatever
you're trying to boost with entanglement,

and then you want to have even better
entanglement, which I call it high

dimensional entanglement, then you need
something that tells you how good it is.

And of course, like everything
in quantum these tools are not

just out there until we come in,
hopefully, and they will be out there.

Dan: Okay, so you're at the stage
of kind of building proof points and

Building the hardware and
software that does this mechanism

that we're talking about.

These Bell states that you're
talking about are they, my simple

mind is thinking, can I just
represent them in a big matrix

instead of a a linear equation with,

you know, two different
factors, two different states?

Natalia: Yeah, density matrix
and it becomes D, so you notice

it's D squared times D squared.

So it's actually gigantic

Dan: Yeah.

Natalia: Yeah, and it's really, it
gets really funny if you talk with

my postdoc the postdoc in our group
he, he could just have three hours of

how you can build these matrices and
measure them really fast and, with

assumptions and non assumptions and
compress sensing techniques, which is

something we would also like to put
maybe, eventually, maybe in a box.

If you, somebody is, let's say, it's not
only about the entanglement source that we

could provide, but if you have a quantum,
quantum state, and in, and it hopefully

gets bigger, because we want to make
states that, for computing, that are big

and useful, if you just want to benchmark
them or measure them, That's hard.

That takes time.

And you have to start putting tools to
make that fast, computationally even,

not physically, not just the measurement
itself, but because your computer

runs and characterizes that faster.

That's another whole challenge
that we also like to think of.

So at this moment, obviously for
the project of commercialization,

we're not even close to that.

Like it's only at the beginning.

We know how to do sources.

We think we can now put them in a box.

build that repeatedly and reliably.

So we're going to be starting building
prototypes and testing them, which

I think is an important thing.

It's not only that we know that the
box is working, but we, that we've

developed partnerships that are
going to be strategic for testing

this in relevant environments.

Because, yeah, that, I think that's, we
cannot say we have a box until we haven't

really tailored it to our end users.

Yeah, our clients more like it

Dan: I was, I was going to ask
about the use cases again, in the

light of the hyper entanglement.

There any at the moment, or is this
purely theoretical at the moment?

I, of course you could probably
just run something like QKD E91

and it would just consume the
type of entanglement it needed.

It wouldn't then use the
additional dimensions.

Do you think there's a future mode
of communications and computing

that uses, I know there's research
into Qdits for computing and so on.

Does this mix into the same
kind of domain as that?

Natalia: Yeah, like, so if,
because there's Two things, there's

one that just high dimensional.

So just trying to work with.

more than beyond binary encodings
in one degree of freedom.

And there's a lot of protocols already
in, yeah, like you have high dimensional

QKD protocols and then you have also
try to look at computing and photonic

platforms computing that will be using
Qdits for better fidelity and encoding

communications, better robustness.

Now for the hyper entangled states, which
are the ones that will be just in space

and time, I think it's very early on,
as I think it's, we've only seen, it's

really on the research side of trying
to build the states and being able

to just, yeah, having a good resource
there and being able to measure it well.

I do think however, it kind of enters
into the same applications, right?

Like a hyper entangled state
is something that we could be

thinking of a more versatile.

resource if you were actually able
to manipulate it and measure it, then

you have a really powerful and your
single pair of photons or your single

photon only and that could be have
all of these encoding and the resource

and the capability of entanglement On
these different degrees of freedom.

So let's say, for example, I'd see it
as maybe at in for some application, you

want to just use the temporal bit or maybe
it's easier to measure the temporal bit.

But, and, but then you can then.

And a later stages use the spatial one.

I know it's a very
futuristic in that sense.

At this moment, I would say like,
definitely no like, , nobody has there's

no infrastructure to handle this type
of states, like we're even struggling

with something like infrastructure,
if we were to be able to transport it.

spatial spatial modes of light you
have to tell the telecom provider, do

you have a multimode fiber down there?

No, obviously not.

So, it's all about, we, we want to
start working with them to see what can

we do and how can the infrastructure
either stays the same or can change

without a lot of cost to, or that is
a cost that is lower than the gain.

And so it's worth for them.

For example, I think the whole thing of
using different types of fibers, it's only

really useful in the short distance scale.

Like I'm not,

even though obviously there's, I don't
know if you heard, there's been putting

multi core fibers now like two core
fibers, something like that, inter,

like inter oceanic under, yeah, the
ones under the ocean but we're looking

like this is something that will come.

But it's not yet there.

So it's a matter of working along that.

I think for now, spatial entanglement
sources communication will be really

useful in the data center scenario.

I know even like computing side if
we're going to go communication,

we're going to be looking at time.

And then maybe in years like Japanese
people are working fantastically with

Like telecom infrastructure for a spatial
multiplexing and like in classical

communication and we're doing a lot
of work with multi core fibers and

multimode fibers and deploying them.

So you see that the network
infrastructure is already looking at that.

And when the infrastructure is ready, we
want to be ready there to just put it in.

Dan: Yeah I'm, I'm getting a
feel for the ecosystem that's

required to develop these cases.

It's huge and it's the whole stack
from, Supply chain all the way

up to customer outcomes, which
is missing at this point in time.

So it's about building the re
resource, making that reliable, and

then surfing the wave if there is one.

Natalia: it's all about
testing and integrating.

Like I think the power, part of
quantum people understand it,

and, but there's going to be,
there's a lot of work to be done.

There's a lot of, yeah, just
communication, like education of

how to talk between communities
and building test beds and trials.

So there's going to be many years of this.

And.

And I think that's where we're, we
want to work with at the beginning,

kind of fulfill that need.

And obviously then it's a roadmap
when we actually advance the

use of quantum technologies.

But I think, yeah, looking at the
industry, there's so many things to do

and we're just trying to make people
talk to each other and understand each

Dan: That's a good segue.

So you mentioned the roadmap.

You have mentioned different boxes as
you put them, I guess, these are you,

there's a unit, it's a source or detector.

Have you got a product roadmap yet in
terms of the size, features, capabilities,

could you give us a quick overview
on what a source would look like?

What interfaces does it have on it?

Natalia: Yeah,

so.

Dan: How many numbers
of fibers would it have?

I don't know.

I don't know.

Natalia: I ask that myself now.

So I think what we want to be working
with will be first just what we call

the standard entanglement source.

Will be I would definitely at
the beginning be looking at

polarization degree frames.

So I've been talking a lot about high
dimensional encodings, but there's also

a lot of value on just building really
good polarization and degrees frame.

And that's why we also work with
the group of Alessandro Fidrizzi.

Would be like also the co founder of
this project if we ever go through.

So he's merging these two capabilities
of the high dimensional manipulation

and generation with also the engineer
of really high quality sources that

have mostly been in polarization because
they look a lot at, Multipartite thing.

So you need to have just the
best high purity sources.

So I imagined our standard box to be just
a source that will be able to switch.

between applications that you, so if
you want polarization, but then it could

also give you either like just very good
bright source of polarization, or it

could have a high dimensional option too.

And Because it's all SPDC is versatile
and we know how to, this could work.

So it's really tried to provide the user
with a source that could be used for just

polarization encoding, or maybe you have
one to have some high dimensional encoding

and that switch to be easy and reliable.

And then also we have the idea of
customized tier boxes because There,

there will be different applications.

Maybe somebody doesn't want absolutely
everything packed, as you mentioned,

like you, you want somebody that
may be a source that you can touch.

And so that will be a tier box or maybe
just one day, a spatial one, or I'm

looking at temporal degrees of freedom
or just polarization degree of freedom.

So that would be customer tier box,
customized tier boxes for R& D.

I think that would be the beginning of,
and the detectors that will go with that.

Then.

You have to think about the software
layer that will go on top of that and

then the integration to if we were, if
we want to put this into just a network

you need to be able to make the box talk.

So I think that we need a lot of work on
that too development and just grow the

team to have the capabilities to be able
to interface and interoperate these two.

So there's a lot of, we're so early on.

That but we now understand that we
can start with the hardware of the

source and the detection and the
software that will control this.

But then to build on top and work with
partnerships, with the build of the

layers that Could make these boxes talk
to the network infrastructure or to

data centers or computing platforms.

And then also I would like to think
now that when the quantum network and

quantum internet becomes more or even the
computing platforms become more advanced

our multiplexing technology will become.

valuable resource for manipulation of
quantum states, not only from the sources

that we're generating, but their sources
of their memories will need to multiplex.

And we have the tools to do that.

So I can see that as a direction forward
to work with the quantum computing.

different platforms that, they're,
they, either some of them will be able

to multiplex , in time or in space.

And we can come in there to help and
integrate that and boost and scale better.

So yeah, that's, that, that will be what
I'll be like to be looking at the future.

Dan: Really cool.

Let's move on.

I asked a few questions at the end.

I was going to ask you what papers you'd
like to highlight that you've worked on,

but I would say that the one in nature
is probably the main one, isn't it?

Natalia: Yeah.

Dan: link to that in the show notes,

Natalia: Yeah.

That's, I mean, we're really proud of

Dan: with a picture of the
cover that I like so much.

So let's look at the industry itself then.

Have you got a favorite paper or an
influential piece of work that, the

quantum domain that really buzzed
for , know, that really hit the nail

on the head or just blew your mind?

Natalia: I think, so I've, when you
send me the bullet points, this has

been the question that has, I think
was like wow, what could it be?

And I realized that I generally
get inspired with people

first and not the paper.

So I cannot remember obviously then I can
think of their papers working about what

I remember is like hearing people talk and
then that hitting and changing my life.

Yeah.

Literally, so I can tell you my
whole physics path according to

who talked to me or what talk I
gave, I listened to that same.

I was thinking about it and I
think I would like to highlight

when I met Hartmut Haeffner.

So he's like iron trapping in Berkeley
Empire that came out of Ginsburg.

And I heard his talk
when I was an undergrad.

He was talking about, he had just come
out of trap irons and entanglement

sources and just building these things.

And I was, it was an hour or
two hours of a workshop on that.

And I came out of that saying, if I don't
change my life right now, and I'm an

experimental physicist, I will have to
quit physics and look for another job.

Because he just, made me fall in love with
a lab and the excitement of what it would

be to just manipulate quantum systems.

And then a few years after, also in
Mexico, I was in Mexico when I was hearing

them, I heard Roman Quirant and he was
at ICFO at the moment, nanophotonics,

guy working on bio, and Halina Rubinstein
who's and authority and optical tweezers.

And they were all, and Juanpe Torres
also from ICFO, they were all talking

about applications in photonics because
it was the international year of light.

And hearing them talk about the
power of light, not only for, like

for computing for communications
and sensing and manipulation.

It, I said, this is my
field is what I want to do.

And that's how I got into my master's.

So it was really them and then I
also took in my particular master

because I, it was for people.

And I'm like, I need to work with them.

And when I'm on the quantum information
side, I think it was reading papers

or hearing from Gareth Rempe.

That I was just, that was also, I wanted
to go to Max Planck because I'm like,

I need to be with these people that are
doing things with atoms and entanglement

and photons and interfacing these two.

That was fascinating, but it's really been
about hearing people more than reading.

I feel a bit, that I disappoint
there, but it's, yeah,

that's how I get inspired.

Dan: Yeah, no, that's quite
a vivid description of

people and particular topics.

I totally get it.

When you're reading a paper, okay,
you're consuming the mathematics

and the whole context, but you don't
get the passion of somebody really.

Especially a scientific paper.

Come on.

It's not like, yeah,

Natalia: yeah, there's people that
really know how to sell some papers.

I will give that.

But, I'm just also people that
get really inspired by reading it.

But I think it's my side of, I just really
like to talk to people and see them.

And I think that's how I get inspired.

It's that, yeah, it's
a very personal thing.

, . , Dan: so why don't you give us a
bit of a, what's your vision for

the future of quantum networking
now that you've built this amazing

experiment and documented it and so on?

What do you see as the, let's
say, a like 5 10 year type

vision of quantum networking?

Natalia: I think I think my opinion
sometimes changes like every time

that I see news coming in because
to be honest, I've always a bit

skeptical on how far would it be for
us to achieve something practical or

exactly, or even trying to imagine.

What a practical network that relies
on quantum principles looks like.

But now even just the last year
has been so impressive with the,

every single company on quantum
computing, just achieving milestones

and just fulfilling the roadmaps.

So now I'm a bit more hopeful.

And now that I'm been exploring the
market, so I see it as a, as this

kind of tool for just enhancing and
distributing the power of quantum, right?

So it's not only, I think the quantum
network and more like they like to call

it the quantum internet would be not just
a network that would allow for, yeah,

let's say maybe secure communications.

I like to think of one that would allow.

Something that just goes beyond QKD
and allows to implement or think of

more useful protocols that are just not
security, but just related maybe with

computing, there's a lot of talk about
blind quantum computing, for example,

and that's just one of the, yeah, a
protocols that we could do with it.

And then I definitely think that if we
want to achieve what a useful quantum

computer would be and, those, these
applications of pharmaceutical in

climate change, in development of new
technologies, all of these simulations

require tremendous computational power.

And I think that the biggest people
and the most knowledgeable have

already said that this is just going
to be achieved by a distributed.

approach even an error correction will
just be really achieved on a higher

scale with a distributed approach.

So I see networking as a really the
part, like is going to hit when you can

actually interconnect processors and
then think of a quantum computer as a

system of distributed processors that
would be excited to see maybe it won't

look as As fancy as these futuristic
pictures of, like this network all over

the globe with very long distances.

I think maybe we'll see something
just inside a server or maybe between

some servers connecting processors.

And, but I think that's the
thing we should be excited for.

And I think it's also for me
as a personally, as a scientist

the security I understand.

The importance of the application,
for example, securing communications,

especially now we see all of these attacks
or just the, how our digital world is so

susceptible and we rely so much on it.

And, like I get that, it's nice.

It's like, Oh, secure communications, but
really as a scientist, sometimes I want to

think, are we changing the world for good?

And I feel that if we're building a
network that will be able to interconnect

processors or even sensors, I think those
applications not closer to application

for real, like the real world and
real people and could change lives.

So yeah, fingers crossed
that's where we're going.

Let's see,

Dan: Yeah, very nice.

I think you covered almost
all the use cases there.

I do have one piece of opinion.

I can't resist saying is that about the
you mentioned the quantum internet and you

mentioned a map with all the, blue neon
links and stuff, connecting everything.

I hate that term quantum internet.

Natalia: I know.

Dan: say I hate something, but it is it's
hard to imagine it being anything other

than something from a sci fi novel by N.

M.

Banks or something.

Natalia: Yeah, I think that's why
I say I put it on like some people

like to call quantum internet.

I think it's a term that has mostly
been coined because when you need, when

you're talking with, Like outside of the
scientific world and trying to explain

to people why could this be useful
is I guess saying the internet Gives

you this idea of wow, it will be big.

It will be useful.

It will be around

Dan: it's also common language so
anybody can understand it really,

because it's it's ubiquitous, isn't it?

Natalia: yeah, but at the same time I
also think is a great tool for to say that

We have no idea Why, like how it could
be useful because every time they talk

about like the quantum internet alliance
talks, they're saying we're figuring it

out even we didn't know when the internet
started like these we didn't know what

we were going to be doing with it.

So they like to envision.

That when we're building this new
quantum enabled network, it would

be something that, right now, we're
just thinking of a few applications,

but maybe it could go really far.

And I think it's a hopeful idea.

But yeah, indeed, I also feel it's
super futuristic and it's always

the blue neon lights in this
interconnected world all over.

And I'm like, Huh.

Really.

Let's see.

Dan: This entanglement
has to be blue, right?

Actually, no, it should be
infra red, shouldn't it?

Natalia: I Look, I Yeah mostly
it should be infrared, but I just

like to put everything purple
in all of my posters and talks.

It's just You know, so
So, I would go for it.

Dan: You could start
campaigning for the purple

Natalia: Yeah, purple inter I
think, I think Qunnect already has a

cover, they, they have the prettiest

colors, pink purpley, yeah, it's they
already have my favorite palette cover

Dan: Very nice.

Okay, cool.

So yeah, just moving towards the
end of the our interview here.

I'd like to ask about what you
do to wind down from science, to

disconnect from highly logical,
highly technical mathematical world.

I imagine you have a few things
going on why don't you share

Natalia: yeah hopefully I think it really
changes with respect to where I'm living

because obviously as a migrant you adapt
to whatever whatever place you are.

I think I would say when I was when I
was younger and living in Colombia, the

way that I would wind up would be just
to really just hang out with my family.

And not talk to any
single scientist at all.

If anybody would want to take me to
a science museum, I'll get very angry

cause I was like, I don't want to work.

I think here, for example, and because
I also lived in a very big city at

the time and Bogota is a big chaos.

We cannot really do much in the city,
even though you have so many options

with traffic what I love for now about
living in Edinburgh is I'm in a capital

city, but It's so tiny and also you're
surrounded by just beautiful nature.

So if the weather is good, I always
try to, this summer I've been too

busy, but generally I like go camping
I don't know why I'm so masochist just

sitting in the Scottish highlands with
like next to a fire freezing and the

rain pouring on me, me holding a cup.

And I'm surrounded by midges
and I say life is good.

, that's a nice one.

And where I'm in the city, just to
be honest, I like eating, which is

really, not so exciting, but I just,
going out with friends, sharing a

meal talking maybe some cocktails.

To be fair, I just find out
when I'm surrounded by people

I get recharged with it.

And I miss my people so much that
I like to build a community here

and yeah, nurture myself with it.

So yeah,

Dan: nice,

Natalia: pretty much.

Dan: In terms of getting up on
the mountains, do you, is it the

Cairngorms or have you been up Ben

Natalia: Nevis

Yes.

Oh no.

So I, this is the other thing.

Like I, I was born.

Pretty much with really bad knees.

So I have the perfect excuse to not
go to any hike that every single

person here would invite you.

Dan: And you're South American,
so really you are kind of

allergic to the cold, really.

It's in your

Natalia: yeah, no, exactly.

The I'm, funny enough I'm quite
resistant compared to other people here.

I don't know.

I think because I live in Bogota, it's
always the worst weather of the country.

So I'm used to just being
miserable, whatever I am.

And I think Edinburgh just feels it
feels like home, but yeah, thank God

I just, I don't go, I don't go hiking.

I just like the outdoorsy bit part.

I'm like, yeah, just go.

I'm going to sit here and just enjoy
the, just sitting here or more, or

a very small, as very small walks.

A lot of people go to the, to
Cairngorns, but I like the Loch

Lomond area the the TRX a bit more.

But even, or the, but then you have the
islands, like Scotland is just beautiful.

Even when it's miserable weather you
still appreciate how beautiful it is.

So I'm very lucky.

Dan: I'm going to wrap it up there.

Thanks very much for your time

Natalia: No, thank you.

It is great.

Dan: we, I hope we cross paths again.

Thank you,

Natalia: Absolutely.

Thanks that.

Dan: I'd like to take this moment to
thank you for listening to the podcast.

Quantum networking is such a broad domain
especially considering the breadth of

quantum physics and quantum computing all
as an undercurrent easily to get sucked

into So much is still in the research
realm which can make it really tough for

a curious IT guy to know where to start.

So hit subscribe or follow me on your
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