Categories: world

Researchers find a way to improve the performance of quantum computers

Credit: CC0 Public DomainUSC researchers have shown a theoretical approach to improving quantum computing performance, an important step to scale…

Credit: CC0 Public Domain

USC researchers have shown a theoretical approach to improving quantum computing performance, an important step to scale a technology with the potential to solve some of society’s biggest challenges.

The method addresses a vulnerability that assesses the performance of next-generation computers by suppressing inaccurate calculations while increasing results, a critical step before the machines can outperform classical computers as intended. Called “dynamic relaxation”, it worked on two quantum computers, proved easier and more reliable than other solutions and could be reached through the cloud, which is a first for dynamic relaxation.

The technology manages staccato outbreaks of small focused energy pulses to compensate environmental disturbances that make sensitive calculations. The researchers report that they could maintain a quantum state up to three times longer than would otherwise occur in an uncontrolled state.

“This is a step forward,” said Daniel Lidar, professor of electrical engineering, chemistry and physics at the USC and head of the USC Center for Quantum Information Science and Technology (CQIST). “Without debugging, quantitative calculations can not overcome classic data processing.”

The results were published today in the journal Physical Review Letters . Lidar is Viterbi Professor of Technology at the USC and corresponding author of the study; He led a team of researchers at CQIST, which is a collaboration between the USC Viterbi School of Engineering and the USC Dornsife School of Letters, Arts and Sciences. IBM and Bay Area startup Rigetti Computing provided cloud access to their quantum computers.

Quantum computers are fast but fragile

Quantum computers have the potential to make outdated supercomputers today and drive breakthroughs in medicine, finance and defense capacity. They utilize the speed and behavior of atoms, which work radically differently than silicon computer accessories, to perform seemingly impossible calculations.

Quantum computing has the potential to optimize new drug treatments, models for climate change and patterns for new machines. They can achieve faster delivery of products, lower costs for manufactured goods and more efficient transportation. They are driven by qubits, the subatomic work horses and the building blocks of quantum computing.

But qubits are as temperamental as high performance racing cars. They are fast and high-tech but vulnerable to errors and need stability to achieve calculations. When they do not work properly, they produce poor results, limiting their ability to traditional computers. Researchers around the world have not yet achieved a “quantum advantage”, the point where a quantum computer exceeds a standard computer on all assignments.

The problem is “noise”, a catch-all description for noise such as noise, temperature and vibration. It can destabilize qubits, creating “decoherence”, an upset that interferes with the length of the quantity status, reducing the time a quantum computer can perform when achieving correct results.

“Buller and decoherens have great impact and destruction calculations and a quantum computer with too much noise is useless,” explains Lidar. “But if you can overcome the problems with the sound, you begin to approach the point where quantum computers become more useful than classical computers. “[1

9659005] USC Research Spans Multiple Quantum Platforms

USC is the only university in the world with a quantum computer, its 1098-quartz D-Wave quantum annealer specializes in such a boost optimization issue. Part of the USC-Lockheed Martin Center for Quantum Computing, located at the USC Information Science Institute. However, the latest research results were not achieved on the D-Wave machine, but on a smaller scale, general quantum computers: IBM’s 16-quart QX5 and Rigettis 19-Quartz Acorn.

In order to achieve dynamic relaxation (DD) researchers, the superconducting qubits bathed with closely focused, timed pulses of minute electromagnetic energy. By manipulating the pulses, researchers could envelop the qubits in a micro environment, sequestrated or relaxed from ambient noise, thereby maintaining a quantum state.

“We tried a simple mechanism to reduce the failure of the machines that proved to be effective,” says Bibek Pokharel, a doctoral student for electrical engineering at USC Viterbi and the first author of the study.

The time sequences for the experiments were by far small with up to 200 pulses that span up to 600 nanoseconds. One billion of a second or a nanosecond is how long it takes to easily travel a foot.

For IBM’s quantum computers, final credibility improved threefold, from 28.9 percent to 88.4 percent. For the Rigetti quantum computer, the final credibility improvement was a more modest 17 percent, from 59.8 to 77.1, according to the study. Scientists tested how long the credibility improvement could be maintained and found that more pulses always improved things for the Rigetti computer while there was a limit of about 100 pulses for the IBM computer.

Overall, the results show that the DD method works better than other quantum error correction methods so far tried, said Lidar.

“As far as we know,” wrote the researchers, “this is the first unambiguous demonstration of successful deco combat in cloud-based superconducting qubit platforms … we expect the lessons that will be of great applicability.”

High effort in the quantum superiority competition

The search for quantitative estimation superiority is a geopolitical priority for Europe, China, Canada, Australia and the United States. The benefits of acquiring the first computer that makes all other computers outdated would be huge and give economic, military and public health benefits to the winner.

Congress is considering two new bills to establish the United States as a leader in quantum computer. In September, the Representative House approved the National Quantum Initiative Act to allocate $ 1.3 billion in five years to stimulate research and development. It would create a National Quantum Coordination Office in the White House to monitor research nationwide. A separate bill, Quantum Computing Research Act by late Kamala Harris, D-Calif., Instructs the Department of Defense to lead a quantum task.

“Quantum computing is the next technical limit that will change the world and we can not afford to fall behind,” Harris said in prepared comments. “It can create next-generation jobs, cure diseases and, above all, make our nation stronger and safer… Without sufficient research and coordination in quantum computers, we risk falling behind our global competition in cyberspace races, leaving us vulnerable to attacks from our opponents, “she said.

Explore further:
Quantum Cloud Services enters the arena with a high price range

More information:
Bibek Pokharel et al., Demonstration of Fidelity Enhancement with Dynamic Relaxation with Superbative Qubits, Physical Review Letters (2018). DOI: 10,1103 / PhysRevLett.121.220502

Journal Reference:
Physical review letter

Provided by:
University of Southern California

Published by