A trio of theorists, including one from the NIST, have
described how a future quantum computer could be used to simulate complex,
high-energy collisions of subatomic particles. Given a working quantum computer—still
under development—the algorithm could solve important physics problems well
beyond the reach of even the most powerful conventional supercomputers.
High-energy particle collisions represent one of the most
important frontiers of modern physics, but the interactions involved are so
complex they often cannot be calculated from existing models. It’s an
experimental science, and one that requires big experiments like the
multibillion euro Large Hadron Collider (LHC).
Modeling such collisions would not be beyond a quantum
computer, however. Also the focus of intense research, such machines will take
advantage of quantum mechanics—the laws that govern the interaction of
subatomic particles. These laws allow quantum switches to exist in both on and
off states simultaneously, so they will be able to consider all possible
solutions to a problem at once.
“We have this theoretical model of the quantum
computer, and one of the big questions is, what physical processes that occur
in nature can that model represent efficiently?” said NIST theorist
Stephen Jordan. “Maybe particle collisions, maybe the early universe after
the Big Bang? Can we use a quantum computer to simulate them and tell us what
Questions like these involve tracking the interaction of
many different elements, a situation that rapidly becomes too complicated for
today’s most powerful computers.
The team developed an algorithm—a series of instructions
that can be run repeatedly—that could run on any functioning quantum computer,
regardless of the specific technology that will eventually be used to build it.
The algorithm would simulate all the possible interactions between two
elementary particles colliding with each other, something that currently
requires years of effort and a large accelerator to study.
A substantial amount of the work on the algorithm was done
at the California Institute of Technology, while Jordan was a postdoctoral fellow.
His co-authors are fellow postdoctoral research Keith S.M. Lee (now a postdoctoral
researcher at the University
of Pittsburgh) and
Caltech’s John Preskill, the Richard P. Feynman Professor of Theoretical
“We believe this work could apply to the entire standard
model of physics,” Jordan
says. “It could allow quantum computers to serve as a sort of wind tunnel
for testing ideas that often require accelerators today.”