Hello, and welcome to the Physics World weekly
podcast. I'm Hamish Johnston.
In this episode, we're going to chat about
the 2025
Nobel Prize for Physics,
which has been awarded to three
pioneers in the field of superconducting
quantum circuits.
But first, I'd like to acknowledge
the generous support of American
Elements
for this episode.
American Elements,
the world's manufacturer of engineered and advanced materials.
American elements,
now invent.
On Tuesday morning, John Clark,
Michelle Devoret,
and John Martinez
bagged this year's Nobel Prize for Physics
for the discovery
of macroscopic
quantum mechanical tunneling
and energy quantization
in an electric circuit.
That circuit was a superconducting
device called a Josephson junction,
and their work, which was done in the
nineteen eighties,
has led directly
to a leading family of nascent
quantum computers
that are being developed by tech giants and
startups alike.
These use superconducting
circuits as quantum bits, and their physical form,
resembling
a glittering
copper chandelier,
has become an icon of quantum computing.
To chat about this year's laureates and the
wide reaching
scientific and technological
consequences of their work,
I'm joined by Ilana Whisby,
who is a quantum physicist,
deep tech entrepreneur,
and former
CEO
of Oxford
Quantum Circuits.
Hi, Ilana.
Welcome to the podcast.
Hi. Thanks so much for having me.
Yeah. Thanks for coming on, Alana.
You know, when when we thought about
how to cover this in the podcast, I
was really keen
on getting somebody,
with a sort of industrial
commercial background
and a bit of experience with the sort
of quantum technology
that these, three laureates developed. Because I know
it's, you know, it's it's it's had a
very important
implications
in the, sort of, quantum computing industry. So
it's really great,
to have you on.
And as someone who's worked with superconducting
qubits, I'm guessing that you're very pleased with
this Nobel Prize. You seemed very pleased yesterday
when I first contacted you about it.
Yeah. Absolutely. I mean, the whole the whole
field, the whole ecosystem is obviously delighted. I
can probably talk on behalf of them
at that point in time.
I mean, really because the prize recognises,
the experiment, really, that was a foundation for
turning
a theory about atoms
into the field we have today with, superconducting
quantum circuits, which
underpins quantum computing and and so, so many
other things. So, yeah, we're certainly absolutely, absolutely
delighted, especially
considering,
it's the international year of quantum.
So I think the timing as well is
is particularly,
particularly poignant for us.
That's right. Yeah. I it's we we you
know, on Physics World, we do make predictions
every year about who's going to win the
the Nobel Prize. And,
and this year, you know, I think possibly
influenced by the fact that it is the
International Year of Quantum Science and Technology.
We did go for a quantum prize, but,
of course, we got we we we were
completely wrong. We we thought it was gonna
be quantum
algorithms, you know, the theory
of quantum computing. And instead, of course, it
was the exact opposite.
It was the people who did the hard
work,
and and built,
I suppose, the the some of the earliest,
qubits.
So
can you explain how the work done in
the eighties by Clark,
Devore,
and Martinez
has led to the superconducting
qubits and processors
that we have today. So what did they
do back then? And and, how did it
lead to,
the quantum computers of today?
Yeah. I mean, I can I can certainly
do my best to whiz you through a
little bit of history, but also then, of
course, the impact that it's had, in shaping
today's industry as well as kind of fields?
But
I think maybe if I zoom out and
do a bit of history first,
but before I do that, that verdict upfront,
what they actually did,
between Clark, Taberae, and Martinez is prove effectively
that a manmade
electronic circuit,
can behave as one quantum object.
So that single result is really what has
led us to be able to engineer,
quantum behaviour on chips, which is obviously the
field of superconducting
quantum circuits,
which underpins
a huge amount of the quantum computing industry
and and how it runs today.
So we just take a a quick step
back. But before the nineteen eighties, I think
it's probably worth putting it a little bit
into context of what we knew
already, kind of the ecosystem that they were
operating in.
So if we start they had superconductivity.
Right? That was understood,
that you could cool materials and electrons
pair up and flow in kind of Cooper
pairs. So it was like ECS theory. This
was kind of already a theory that was
understood and actually earned the 1972
Nobel Prize.
There was also this other additional,
concept that wasn't just a concept or a
theory. It was also demonstrated in experimentation.
And that was
that those Cooper pairs can start tunnelling
and you can use tunnelling as a tool.
What that really means is that this kind
of quantum mechanical effect allows particles to slip
through barriers.
And it was used as this measuring
instrument.
In semiconductors,
it was shown in in devices there. There
was also tunnel junctions for spectrometers
in the superconducting kind of energy gap piece.
And of course, Brian Josephson
had first predicted
that there was this superconducting
insulator,
superconducting
kind of stack that could be created,
which we call the the Josephson junction,
in which pairs of electrons could tunnel
together,
in a a zero voltage super current. And,
effectively, you can have,
this kind of tunnelling effect. And that was
demonstrated
already within what we call SQUIDs,
which were very, very sensitive,
magnetometers.
And again, that one was also recognized by
the 1973
Nobel prize. So I think all of this
is really useful background
context,
as to the environment,
that these three were kind of operating in.
But the question that
they really went out to answer was was
a bigger question. It was like, can
an electrical circuit itself
show
unmistakably
quantum behavior
in the same way
that an atom does?
And that question is super important because if
the answer to that is yes, which effectively
they were able to go out and prove,
then
that would basically mean you can create
human
artificial
atoms
mechanically engineered through
electronic circuits.
So.
Really
the team, when the three guys were over
in Berkeley, they asked that question.
And
that question was really at that point in
time, can it behave like a single quantum
object? And what they did was they ran
very tightly shielded, very kind of complex
engineering to fully characterise this kind of experiment.
And what they were able to prove is
is two key facts that classical physics
could not explain.
The first was this concept of macroscopic quantum
tunneling. So below
specific temperature, they had this so that you
can't put it into context. They had a
superconducting
circuit,
probably within
a a cryostat,
a a very cool type,
environment where you had your,
your your metal, in a a superconducting,
low TC manner.
And what they were able to do was
create an engineer,
single trace in junction.
And through that trace in junction, they were
able to demonstrate the rate at which the
device,
leaves a non zero voltage state becomes independent
on temperature.
And what that was proving was that if
it were an ordinary kind of thermal escape
of this experiment they were doing,
then colder wouldn't always been slower and it
didn't. So this was the first point is
that they were to prove this macroscopic quantum
tunneling existed
within that type of, of, of environment. The
second
was this discrete energy step in the circuit,
which really underpins this nonlinearity
for creating an artificial atom. So what they
were able to do was apply
these precise kind of microwave
tones, I. E, specific microwave frequencies
to this junction.
And the device would would be able to
identify, okay, this voltage change, this Cooper pair
tunneling
at specific frequencies at the right harmonics
exactly where the quantum theory predicted it at.
And they were, of course, able to do
that reproducibly
with, you know, significant rigor and show effectively
sorry, it's hard to explain without going a
little bit,
kind of into the quantum physics, but the,
the phase is a collective variable on this
device, which contains billions of electrons has actually
got quantum
quantized
energy and tunnels.
So effectively proving out
in experimentation,
the quantum mechanics
from atoms and ions
to
engineered
superconducting circuits. And this is absolutely
Nobel Prize
worthy. Right? Seeing quantum behaviour
demonstrated in a macroscopic
manmade circuit,
not just in kind of microscopic
particles as we'd understood it before. Absolutely huge.
The fact that there was complete kind of
unambiguity
in the evidence,
both the temperature independent escape, as well as
that microwave resolved
step, they rule out classical explanations.
And then of course, most importantly, from my
perspective, the impact that that has,
it unlocks
a toolkit, a mindset that,
Devray in particular was able to take on
and really became the foundation for circuit QED,
circuit quantum electrodynamics,
which is really the foundations for modern superconducting
qubits,
quantum limited amplifiers.
And a part which actually
I really want to touch on as well
is
the human aspect.
If we, if we look at kind of
the, the, the way that these
three individuals
both ran their research group,
across Berkeley, you know, where Devore came from,
went across to Saclay, Martinez,
Martina's, of course, going on to to Google
and,
and Clark's kind of Berkeley Lab as well.
Like, if you look at the human impact,
the training that they had in the fields
that they then kind of coined, like, I've
always thought of
these people and this seminal paper, which
when I was doing quantum
physics,
quantum mechanics before even going to the laboratory,
these were papers I had read. And they're
papers that pretty much
every single person that operates in the space
will have, have recognized, or, you know, maybe
you've looked at Martinez's lectures,
or Jeffrey's lecture notes. And,
and I think it's, it's also this
kind of human spawning
as well as the technical
spawning,
that these almost like godfathers
of the field,
we're able to, to kind of catalyze with,
with this work. So, Alana, the the superconducting
qubits that, that we see today, and, you
know,
these these are used in in quantum processors
that are that have been developed by huge
companies and and small startups alike.
Are are the superconducting
devices
today, are they
very similar to what,
the Nobel laureates
developed in the mid eighties? Or are they
essentially better versions
of of what they developed? Or or has
the technology evolved
quite a bit since then?
Yeah. Thankfully, of course, technology has evolved, quite
a bit from then.
But really this is this moment was kind
of that that first
experimental proof point, right, that you could start
to manufacture or create some sort of manmade
circuit,
with this property that
then turns into these,
these cubits, right, where you've got your LC
oscillator with your specific Joseph's junction,
within now at first, when they first tried
to create cubits and control it, the quantum
information processing.
My understanding is that, actually, they were looking
at it from a different approach with with
charge based mechanisms.
And you were really limited in terms of
what we call the coherence time, I. E.
The the amount of storage time that quantum
information could be held and manipulated,
in that type of approach. But,
actually what came from that was further development,
into what we call the transmon.
Now the transmon,
there's another paper, which maybe that's one as
well, which might be up for a future,
quantum,
future,
Nobel prize, but this was really Deveray and
his wider research group. So then you kind
of move on to Deveray and Sholkov and
Warrath and kind of circuit QED methods,
which are all based off this Transmon
type approach. But fundamentally,
that Transmon
includes, of course,
all or is built upon all of the
understanding,
of of that original
kind of circuit QED piece,
but,
is is engineered in a way that means
that what we can do is start to
optimise all of the different components within it.
For example, you you couple it to a
microwave resonator,
so that you can start to increase their
coherence time. You would cross some charge of
phase. So there's
fair amount of research that's gone on just
to even get to the point of the
transmon, but the transmon then,
underpins,
I would say, pretty much the entire superconducting
quantum circuit space,
today. So any quantum computer, you know, IBM,
of course, Oxford Quantum Circuits,
IQM,
Rigetti,
I think AWS.
They're all based on this core Transmon type
technology,
which is from that core circuit QED toolbox
that was was first demonstrated here.
And,
can we get on to, Oxford Quantum Circuits,
Alana? You,
cofounded
that UK based company in 2017,
and, it uses
superconducting,
circuits. Can you can you talk a bit
about the challenges
of taking
superconducting
circuits out of the lab,
back in 2017
and
creating,
practical
commercial systems. Was it,
I'm guessing there were a lot of challenges
involved in that commercialization.
Yeah. Of course. And and for anybody in
the space, there there still are.
So I joined OQC, Oxford Quantum Circuits as
founding CEO alongside Doctor. Peter Leek, from the
Oxford physics department.
I think this is a really great example,
right, of where you can have a core
technology, a core piece of IP or an
idea that sits within academia.
But there's a really long way to go
and to be able to turn, you know,
an idea or a concept or, an early
kind of,
piece of science through into,
a commercial system. Right? That's a long path
and a long journey.
If we specifically start just looking at the
actual qubits themselves, like the approach we were
able to take there was how can we
kind of utilize that deep relationship with the
university
whilst it's the technology is still a kind
of early technology
readiness
to both prove out the physics and build
confidence in the physics.
And then what I was able to do
is the CEO is come in and go,
right. Okay. How do we now turn this
into an actual system? How do we de
risk technology in university and build a stack?
And that's a lot more than just kind
of proving out a key bit. Right? That's
optimising,
reproducibly
at scale,
but also building the rest of a computing
stack, which requires significant kind of multi interdisciplinary
teams pulling from
industry,
across the world.
And
of course you have the qubit itself with
these individual,
transmons for oxo quantum circuits. That's the coaximon,
which was the invention from Peter Leake in
in the physics department.
But, of course, you then also need to
build the rest of the stacks or the
control hardware, the control software. And one of
the things that I was really passionate about
is, like, making sure that we were putting
the customer, right, the commercial mindset at
the forefront of everything we were doing. I
don't think it's worth or
correct to build technology in isolation. So
for us,
one of the first key milestones we did
was prove out a kind of end to
end vertical slice
with the first system, which was only four
cubits.
But we connected up to,
a consumer, a customer that was running an
algorithm.
And at each point, we've always tried to
keep the customer at the forefront of everything
we were doing, and that meant providing them
access.
You know? And when you do that, you
get,
you get a deeper understanding, of course, of
the
the challenges, both from a technical but also
from
a systems integration
perspective,
for the for the consumer.
And at the end of the day, the
the kind of really,
I guess,
challenging thing for the quantum physicist think about
is that ultimately the consumer doesn't care whether
it's quantum
or not. Like, we want to be able
to solve their problems. So you need to
be able to find a way to zoom
out,
as as well and really focus on the
type of problems that they have,
and really think about, you know, security.
How does this integrate into their existing workflow?
But at the same time, you've also got
to build from the bottom up. And, you
know, this is true for all quantum companies
out there today is that the systems that
that we have
and the, the progress that we're making with
the, the actual, I'd say performance of the,
the quantum bits, be it through superconducting circuits
or NV centers or silicon or ion traps.
No, it's, it's really improving rapidly, but we
need to be able to do this at
tens of thousands, if not millions
of cubits
reproducibly
with high quality, with super low latency,
in a manner that is seamless,
and kind of integrated into
the existing industry. And that's really challenging.
I think it's worth touching on, if you
don't mind, like, the superconducting circuits in particular
here, because
where you have Josephson junctions and this kind
of core piece, still one of the biggest
challenges is that that's the core component that's
really challenging
to reproduce at scale,
with with high yield.
And it's not something that
exists in the existing semiconductor
supply chain,
as a kind of methodology. So that is
one of the biggest challenges,
for any of the superconducting
circuit players today.
And you you mentioned, that superconducting circuits, they're
they're not the only game in town when
it comes to creating qubits and and and
quantum processors.
Are we
do we are we still in the mindset
that there is going to be one
type of qubit technology, be it superconducting
or something else, that's going to win out?
Or
could we see a future with with a
number of different types of qubits
integrated together? So, you know, you might have
superconducting
qubits, you might have
optical NV qubits and trapped ions all
in one system or connected on a quantum
internet.
What's
the view,
in the industry today about
the, you know, the race for the ultimate
qubit?
Well, I think,
maybe my view is different from the view
across, across the industry today. So if you
go and speak to any of these individual
companies, of course, they'll tell you rightly so,
why their single technology will, will, will win.
But for me, I mean, I did my
PhD originally in hybrid quantum systems. So I
was doing superconducting circuits coupled with,
spin ensembles,
and got to work with, different spin mechanisms
as well.
And
if you look at the progression
of, say, classical compute,
I honestly think it would be
naive to think that any one single technology,
or kind of underlying,
quantum basis is going to be
utilised for absolutely everything.
So I don't think there's a winner take
all, technology. I do think it's worth still
investing in multiple different technologies.
And I do see a world in which
we've got
different underlying types of qubits,
optimised for different applications,
and that they probably will be hybrid quantum
computers or networks
in in some form,
in in the future. So I'm a firm
believer in in hybrid quantum systems to that
moment.
And I think today you've got,
you've got a fairly good overview, don't you,
of
of of of the quantum industry
and, you know, who who's investing what, and,
you know, what technologies are are hot, and
and maybe what technologies are fading.
How would you characterize the industry today?
Is it,
has it has it matured quite a bit
from, say, 2017
when you when you first kicked off with,
Oxford Quantum Circuits? You know, how how has
it changed, and,
and where where is it heading? Yeah. For
sure. I mean, look, when I was
first
fundraising
and building the first quantum computers over at
OQC, like, honestly, I should have run a
consultancy just educating,
consumers, investors.
I probably would have made more money and
more progress,
because it was a really, really nascent space.
Right. Consumers didn't know,
what what the technology could could do yet.
So there's a lot of education there.
The investors were really still developing their thesis
on where they would invest and understanding the
fundamentals,
of, of what it would take.
Fast forward to
today,
that has significantly
shifted,
as a landscape, both from a consumer perspective
where the early adopters, particularly across finance, across,
materials discovery, across,
simulation,
of underlying kind of molecular
dynamics,
and and so much more across both and
I broaden this now to to computing, sensing,
and communications.
The industry has has matured rapidly. Now there's
still
a long way to go, of course. We
still need to make sure that we are
building
quantum computers that will eventually be fault tolerant
in capability. We are still
on the cusp of,
kind of coming out of the the NISC,
noisy intermediary scale quantum era
where,
we are pushing the boundaries of what can
be simulated.
But most importantly, I think you've got really
smart end users,
and you've also got really
rapid
technological development
across lots of different underlying
quantum technologies proving
that we are seeing significant,
traction,
which which gives us confidence that we will
meet,
and eventually surpass kind of that quantum advantage
point likely in the next year. If I'm
maybe maybe that's my prediction. We'll see whether
we're true,
true next year or not. But I'd say,
you know, characterizing overall, we've gone from
we've gone from early demos,
to a lot more maturity.
We've got full systems. We've got a really
competitive
ecosystem.
We've got a maturing market, and we've got
a much more
smart, ready, capable,
investor,
market as well. I think even the amount
of investment that's gone in the last '24
to '20 last year, like, 2024 to 2025,
I think it's, like, doubled.
So we're seeing a lot of money, a
lot of talent,
and a lot of expertise,
in the space, which is is really, truly,
exciting.
And what's your role,
Elana? What are you up to at the
moment? Are you are you are you on
the business side of things, or are you
back
in in the lab, or is it a
bit of both for you? That is a
a great question. Thankfully for everybody, I'm not
in a laboratory
because
as much as I absolutely loved being an
experimentalist,
I was definitely much better as a CEO
than,
doing the actual kind of, fabrication,
my myself. So we will we all play
into our strengths.
But, yeah, right now I'm actually exploring
a few stealth projects. Of course, it's where
deep tech and quantum primarily meets leadership.
So there's a number of teams in quantum
across different technologies,
where I'm able to help them in their
earlier stages. There's still plenty of room,
in in the market,
to set up with their vision, their mission,
their values.
And I'm really enjoying kind of helping support
the ecosystem
to up and grow in that way, both
I mean, I'm an entrepreneur.
I am founding,
for sure.
But also I'm I'm really enjoying
advising early stage teams and getting to know,
yeah, different different teams, different setups from
around around the world.
And if I can kinda give a little
a little teaser,
I know if you know,
Rumi's
quote. It's is like out beyond the ideas
of wrongdoing and right doing. There is a
field
and I'll be there.
And finally,
Elana, I'd like to sort of co opt
you in our sort of ongoing project of
trying to predict the next,
Nobel Prize for Physics, something that here on
Physics World, we well, we're we're luck we
we luck out occasionally, I think. We get
it right occasionally, but normally we get it
wrong.
Is there any research that's being done today
in quantum physics
that you find really exciting and you think
could merit a future
Nobel Prize?
So get that quantum crystal ball out.
Yeah. I mean, look, there's so much exciting
work,
happening.
I think realistically,
anybody who makes a reliable error corrected
quantum computer, like the first to that, like,
absolutely deserves absolutely deserves one because that would
be undeniable
value.
I think what you said at the beginning
about algorithms is also really important, particularly where
you're looking at new and novel,
error correction, error detection type schemes.
There's a huge amount of innovation there. And
what's kind of interesting actually is the almost
quantum inspired impact on classical,
improvements to algorithm development there as well. But
for me, I mean, it's all about impact.
So if I would love to see a
Nobel Prize then go across to, like, if
somebody has been able to
make
a a discovery,
which
I think for me particularly, it was like
purpose built molecular
qubit type,
sorry, molecular simulation type
manners, then I think that that would,
100%
deserve
a kind of Nobel prize. So quantum enabled
discovery in the real
world. Sorry. It's not more more specific than
than that. No. That's that. I mean, that
goes back to, you know, recently we've been
talking about the purpose of the Nobel Prize
here. Yeah. And we've looked at some sort
of crazy prizes from the past that, you
know, to to modernize. You think, you know,
what are they on about? A prize for
color photography.
But, you know, it does say I think
it does explicitly say invention,
when it comes to Nobel Prize. And yeah,
that that I mean that is an an
interesting idea that, you know, when when, you
know, when somebody invents
an extraordinarily
reliable
quantum computer that, you know, achieves amazing
advantage,
that's, you know,
that would definitely
deserve a prize.
Yeah. Prize to the whole industry.
Well, that's the problem, isn't it? You know,
it's,
I mean, particularly if if that sort of
thing is
is developed
at a big company. Mhmm. I mean, if
it's developed at a small company like Oxford
Quantum Circus, maybe, you know, maybe the Nobel
committee would committee would be able to identify
three people.
But,
I'm sure she would be super happy with
that. Peter and Brad.
That's where I put my money.
Okay. Well, that's yeah. Well well well well
well, we'll put them on our list,
for next year. For sure. They have actually,
had some really good results last year with
a a new type of the Echoaxpond device,
as well called
well, I I'm not gonna talk to it,
but but some people should should also look
it up.
Oh, that's great. Well, thanks thanks, Alana. Thanks
so much for, for coming on, the podcast
and, sort of giving us a flavor, you
know, both about the physics,
but also,
you know, how that research has
essentially spawned,
an exciting new industry.
Thanks for coming on. Thank you so much.
Thank you for the time.
That was Ilana Whisby, who's a quantum physicist,
deep tech entrepreneur,
and former CEO
of Oxford Quantum Circuits.
There's much more about this year's
Nobel Prize for Physics
on the Physics World website.
I'm afraid that's all the time we have
for this week's podcast.
I'd like to thank
American Elements for their generous support
of this episode.
Also, thanks to Ilana Whisby for joining me
today.
And as always, thank you to our producer,
Fred Isles.
We'll be back again next week when we
chat about the effect
of microgravity
on the eyes of astronauts
and how they can protect their vision
in space.
See you then.
American Elements,
the world's manufacturer of engineered and advanced materials.
American Elements,
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