Virginia Tech researchers lead breakthrough in quantum computing

July 25, 2019

The large, error-correcting quantum computers envisioned today could be decades away, yet experts are vigorously trying to come up with ways to use existing and near-term quantum processors to solve useful problems despite limitations due to errors or "noise."

A key envisioned use is simulating molecular properties. In the long run, this can lead to advances in materials improvement and drug discovery. But not with noisy calculations confusing the results.

Now, a team of Virginia Tech chemistry and physics researchers have advanced quantum simulation by devising an algorithm that can more efficiently calculate the properties of molecules on a noisy quantum computer. Virginia Tech College of Science faculty members Ed Barnes, Sophia Economou, and Nick Mayhall recently published a paper in Nature Communications detailing the advancement.

Quantum computers are expected to be able to carry out certain kinds of calculations far more efficiently than the "classical" computers in use today. They are similar to classical computers, however, in that they run algorithms by applying sequences of logic gates -- in this case, "quantum gates," which together form quantum circuits -- to bits of information. For today's noisy quantum computers, the problem has been that so much noise would accumulate within a circuit that the computation would degrade and render any subsequent calculations inaccurate. Scientists have had difficulty designing circuits that are both shorter and more accurate.

The Virginia Tech team addressed this issue by developing a method that grows the circuit in an iterative way. "We start with a minimal circuit, then grow it as we add on logic gate after logic gate in short circuits until the computer finds the solution," said Mayhall, an assistant professor in the Department of Chemistry.

A second major benefit of the algorithm is that Barnes, Economou, and Mayhall designed it to adapt itself based upon the molecular system being simulated. Different molecules will dictate their own circuits, uniquely tailored to them.

The interdisciplinary collaboration between Virginia Tech's departments of Chemistry and Physics -- Barnes, Economou, and Mayhall and a team of graduate students and postdocs from both departments -- have received grants from the National Science Foundation and the U.S. Department of Energy totaling more than $2.8 million.

Virginia Tech and IBM recently established a partnership that gives the researchers access to IBM's quantum computing hardware. "Our team at Virginia Tech is really excited for the next steps in our work," said Economou, an associate professor in the Department of Physics, "which include implementing our algorithm on IBM's processors."

Virginia Tech

Related Quantum Computers Articles from Brightsurf:

Optical wiring for large quantum computers
Researchers at ETH have demonstrated a new technique for carrying out sensitive quantum operations on atoms.

New algorithm could unleash the power of quantum computers
A new algorithm that fast forwards simulations could bring greater use ability to current and near-term quantum computers, opening the way for applications to run past strict time limits that hamper many quantum calculations.

A new technique prevents errors in quantum computers
A paper recently published in Nature presents a protocol allowing for the error detection and the protection of quantum processors in case of qubit loss.

New method prevents quantum computers from crashing
Quantum information is fragile, which is why quantum computers must be able to correct errors.

Natural radiation can interfere with quantum computers
Radiation from natural sources in the environment can limit the performance of superconducting quantum bits, known as qubits.

New model helps to describe defects and errors in quantum computers
A summer internship in Bilbao, Spain, has led to a paper in the journal Physical Review Letters for Jack Mayo, a Master's student at the University of Groningen, the Netherlands.

The first intuitive programming language for quantum computers
Several technical advances have been achieved recently in the pursuit of powerful quantum computers.

Hot qubits break one of the biggest constraints to practical quantum computers
A proof-of-concept published today in Nature promises warmer, cheaper and more robust quantum computing.

Future quantum computers may pose threat to today's most-secure communications
Quantum computers that are exponentially faster than any of our current classical computers and are capable of code-breaking applications could be available in 12 to 15 years, posing major risks to the security of current communications systems, according to a new RAND Corporation report.

Novel error-correction scheme developed for quantum computers
Experimental quantum computers are plagued with errors. Here Dr Arne Grimsmo from the University of Sydney and colleagues from RMIT and the University of Queensland offer a novel method to reduce errors in a scheme applicable across different types of quantum hardware.

Read More: Quantum Computers News and Quantum Computers Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to