UChicago scientists turn IBM computer into a quantum material

UChicago scientists programmed an IBM quantum computer to
become a type of material called an exciton condensate.  Photo by
Andrew Lindemann/IBM
Pioneering experiment could help design energy-efficient

In a groundbreaking study, a
group of University of Chicago scientists announced they were able
to turn IBM’s largest quantum computer into a quantum material

They programmed the computer such that it turned into a type of
quantum material called an exciton condensate, which has only
recently been shown to exist. Such condensates have been identified
for their potential in future technology, because they can conduct
energy with almost zero loss.

“The reason this is so exciting is that it shows you can use
quantum computers as programmable experiments themselves,” said
paper co-author David Mazziotti, a professor in the Department of
Chemistry, the James Franck Institute and the Chicago Quantum
Exchange, and an expert in molecular electronic structure. “This
could serve as a workshop for building potentially useful quantum

For several years, Mazziotti has been watching as scientists
around the world explore a type of state in physics called an
exciton condensate. Physicists are very interested in these kinds
of novel physics states, in part because past discoveries have
shaped the development of important technology; for example, one
such state called a superconductor forms the basis of MRI

Though exciton condensates had been predicted half a century
ago, until recently, no one had been able to actually make one work
in the lab without having to use extremely strong magnetic fields.
But they intrigue scientists because they can transport energy
without any loss at all—something which no other material we know
of can do. If physicists understood them better, it’s possible
they could eventually form the basis of incredibly energy-efficient

“This could serve as a workshop for building
potentially useful quantum materials.” —Prof. David


To make an exciton condensate, scientists take a material made
up of a lattice of particles, cool it down to below -270 degrees
Fahrenheit, and coax it to form particle pairs called excitons.
They then make the pairs become entangled—a quantum phenomenon
where the fates of particles are tied together. But this is all so
tricky that scientists have only been able to create exciton
condensates a handful of times.

“An exciton condensate is one of the most quantum-mechanical
states you can possibly prepare,” Mazziotti said. That means
it’s very, very far from the classical everyday properties of
physics that scientists are used to dealing with.

Enter the quantum computer. IBM makes its quantum computers
available for people around the world to test their algorithms; the
company agreed to “loan” its largest, called Rochester, to
UChicago for an experiment.

Graduate students LeeAnn Sager and Scott Smart wrote a set of
algorithms that treated each of Rochester’s quantum bits as an
exciton. A quantum computer works by entangling its bits, so once
the computer was active, the entire thing became an exciton

“It was a really cool result, in part because we found that
due to the noise of current quantum computers, the condensate does
not appear as a single large condensate, but a collection of
smaller condensates,” Sager said. “I don’t think any of us
would have predicted that.”

Mazziotti said the study shows that quantum computers could be a
useful platform to study exciton condensates themselves.

“Having the ability to program a quantum computer to act like
an exciton condensate may be very helpful for inspiring or
realizing the potential of exciton condensates, like
energy-efficient materials,” he said.

Beyond that, just being able to program such a complex quantum
mechanical state on a computer marks an important scientific

Because quantum computers are so new, researchers are still
learning the extent of what we can do with them. But one thing
we’ve known for a long time is that there are certain natural
phenomena that are virtually impossible to model on a classical

“On a classical computer, you have to program in this element
of randomness that’s so important in quantum mechanics; but a
quantum computer has that randomness baked in inherently,” Sager
said. “A lot of systems work on paper, but have never been shown
to work in practice. So to be able to show we can really do
this—we can successfully program highly correlated states on a
quantum computer—is unique and exciting.”

Originally published by
 | November 12, 2020
UChicago News | The University of Chicago

Citation: “Preparation of an exciton condensate of photons on
a 53-qubit quantum computer.” Sager, Smart, and
Mazziotti, Physical Review Research, Nov. 9, 2020. DOI: 10.1103/PhysRevResearch.2.043205

Funding: U.S. Department of Energy Office of Basic Energy
Sciences, National Science Foundation, U.S. Army Research

Original article