Chemistry labs usually come with a couple standard
things.
You’ve got a chemist in a lab coat mixing
some chemicals, maybe some equipment they
use to analyze their products.
But a new kind of technology could redefine
what constitutes a chemistry lab.
It’s got chemists—and computer scientists—really
excited.
Have a look at this hog.
That’s one of the cutting-edge, cryogenically
cooled quantum devices at IBM, which are available
for businesses and researchers to use—for
a price.
What exactly quantum computers will bring
to the table—or lab bench—isn’t totally
concrete yet.
But chemists and computer scientists are teaming
up now to explore how these machines could
make theoretical chemistry more accurate in
simulating molecules and how they act and react.
Last September, IBM researchers made waves
when they found the ground-state energy of
beryllium hydride, making it the most complex
molecule ever modeled using a quantum computer.
IBM’s computer used six superconducting
quantum bits to represent the electrons in
beryllium hydride, with its whopping 3 atoms.
If that doesn’t sound like a lot of qubits,
it isn’t.
The impressive part of this is the shift in
how the computation itself works.
Let’s back up.
Researchers build quantum computers using
qubits.
Qubits are quantum systems, as are electrons
in a molecule.
When electrons whiz around a molecule, it's not quite right to say they're in a specific energy
state or that they have a specific spin, up
or down.
Instead, they act like they're in each possible
state ... as long as you don't
look at them explicitly.
Although classical computers can approximate
this weirdness through simulations, qubits
are living it.
So the thinking is qubits can better simulate
other quantum systems—like those electrons
flying around a molecule.
Monroe: If I take a benzene ring for instance,
not a lot of atoms in benzene, but there are
a whole lot of electrons and even finding
the ground state of that simple molecule we
use all kinds of approximations.
It turns out, you can represent, in an abstract
way, each electron in benzene by a qubit.
That’s Chris Monroe, a physicist and bonafide
quantum computer scientist at the University
of Maryland, College Park.
His lab traps individual ytterbium ions to
make qubits for its quantum computers.
This one’s got 7 qubits trapped in there,
but the team has run quantum simulations on
up to 53 qubits.
That’s still not a lot of qubits if you’re
thinking about the number of electrons in,
let’s say, proteins or this metal cluster
in an important enzyme, which I’ll get to
in a sec.
Monroe: You can count the number of electrons,
and it's many hundreds.
So that means just to represent this system
you probably require a thousand qubits.
Now, if you want to calculate its ground state,
you might need to do error correction as well.
So to do error correction, you need to redundantly
encode things and you might need another factor
of 10 qubits.
So we're already at like ten thousand qubits.
Manny: But researchers think they’re getting
there, and even solving the relatively simple
problem of beryllium hydride is encouraging.
Monroe: It makes sense to get to speed with
six cubits.
Getting used to how to tweak up that system
will help us when we get the 60 qubits and
600 qubits to protein folding in a really
complex problem.
Manny: And it’s that promise of quantum
computing—to do stuff we can’t do now—that
helps explain why Monroe’s already cofounded
a quantum computing company called IonQ.
And why heavy-hitters like IBM, Microsoft,
and Google are buying into the quantum revolution.
And it's why quantum computing scientist Michelle
Simmons of the University of New South Wales
was named 2018’s Australian of the Year.
While some researchers develop quantum computing
hardware, others like Alan Aspuru-Guzik work
on quantum computing software, which will
help deliver the exact calculations that are
beyond the approximations that classical computers
provide.
Aspuru-Guzik: If you gave them a choice, a
chemist of the future, of an exact algorithm
versus an approximate algorithm, I don’t
know why they’d pick an approximate algorithm.
Only if they are masochists.
Aspuru-Guzik’s lab partly developed the
method that IBM used to run the record-breaking
beryllium hydride calculation, it’s an algorithm
called a variational quantum eigensolver,
and I … definitely know … what that means.
But basically, it’s a pathway to an exact
answer.
If quantum computers could deliver exact answers
about molecules quickly, it could help identify
which molecules are best-suited for certain
jobs.
For instance, Aspuru-Guzik’s lab has launched
a long-term quantum-computational expedition
for molecules and materials that would be
good for photovoltaics.
But it’s important to ask, where are we
going to see quantum computers solving their
first useful problems?
Aspuru-Guzik: Molecules that look like drugs or little active sites or proteins or small
catalytic sites and so on are going to be the first applications.
You really want to solve it exactly, because perhaps there's a lot of strong coordination, there's a lot of transition metals around,
but you don’t have the confidence that
a classical method that is approximate will capture
all of the physics without a lot of calibration.
Manny: One of those active sites he’s talking
about is buried inside nitrogenase.
That’s the enzyme catalyst in bacteria that
breaks nitrogen apart into ammonia, a chemical
that’s used across the entire world as fertilizer
for growing food.
Bacteria use nitrogenase to make ammonia at
room temperature.
Compare that to how we make our ammonia now. It's
the 100-year-old, 400-degree-Celsius process
thought up by Fritz Haber and Carl Bosch.
It sucks up so much energy to produce the
heat and pressure needed that people estimate
that this reaction alone consumes 2% of all
the world’s energy.
So if quantum computing gets us even a little
closer to understanding nitrogenase and coming
up with similar catalysts, we could be talkin’
a huge payoff.
One of the reasons that nitrogenase is driving
chemists crazy is because under all its protein
chains, it has this pesky little metal cluster
called the FeMo cofactor.
It took 10 years after scientists knew the
shape of this thing just to figure out that
there was an atom in the middle of it and
then another 10 to figure out it was a carbon.
So needless to say, progress has been slow. We don’t know as much as we’d like to.
What Aspuru-Guzik envisions is quantum computers
that make researchers better at doing research.
He thinks quantum computers will be good for
not just simulating known molecules and telling
us their properties, but also working alongside
artificial intelligence systems that could
start with desired properties and help chemists
dream up new molecules that possess those
qualities.
This kind of reverse engineering is definitely
a goal down the road.
And even though these are mostly theories for now, Aspuru-Guzik isn’t the only person
who’s excited about it.
John Kelly is the director of analytics at
the quantum computing software company Q Branch,
which focuses on quantum
computing in things like finance and security.
But he’s still aware of the impact it could
have on chemistry.
Kelly: The first application where I saw this,
at my previous position at Lockheed Martin,
we were doing some work with personalized
medicine, and what personalized medicine typically
means is I have your genotypic and phenotypic
information and I have the drug information.
I’m going to predict how you would react
to the drug.
But instead, I want to be able to say I
have your genotypic and phenotypic information,
I want you to have a positive reaction, tell
me what the drug looks like.
There’s no good way of doing that right
now.
Manny: It’s hard to say if or when quantum
computers will have these capabilities.
For one, we just can’t be sure about how
fast quantum computing hardware will advance.
But we can be sure researchers aren’t stopping
because the problems are hard to solve.
Aspuru-Guzik: There are still people who are detractors or kind of not as adventurous.
Well, let them keep doing kind of their incremental science, and let people like me
keep doing more forward-looking science.
You need scientists from both type of sides.
I love them and they should love me too, hopefully.
Manny: Before we go, we want you to know we’ve got nothing against classical computers here
at Speaking of Chemistry.
I mean, you might be watching me on one right now.
And there’s so much more about quantum computing
in chemistry than I could ever, ever hope
to fit in this video or even explain.
So if you want to read a bit more about how
chemistry is making the quantum leap,
steer your classical computer
to our website to read a terrific story by
Katie Bourzac.
And if you want to stay up to date on that
sweet, sweet chemistry news as it happens,
please hit subscribe. You know where the button is.
