Despite steady improvements in quantum computers, they’re still noisy and error prone, which leads to questionable or wrong answers. Scientists predict that they won’t truly outcompete today’s “classical” supercomputers for at least five or 10 years, until researchers can adequately correct the errors that bedevil entangled quantum bits, or qubits.
But a new study shows that, even lacking good error correction, there are ways to mitigate errors that could make quantum computers useful today.
Researchers at IBM Quantum in New York and their collaborators at the University of California, Berkeley, and Lawrence Berkeley National Laboratory report today (June 14) in the journal Nature that they pitted a 127-qubit quantum computer against a state-of-the-art supercomputer and, for at least one type of calculation, the quantum computer bested the supercomputer.
The calculation wasn’t chosen because it was difficult for classical computers, the researchers say, but because it’s similar to ones that physicists make all the time. Crucially, the calculation could be made increasingly complex in order to test whether today’s noisy, error-prone quantum computers can produce accurate results for certain types of common calculations.
The fact that the quantum computer produced the verifiably correct solution as the calculation became more complex, while the supercomputer algorithm produced an incorrect answer, provides hope that quantum computing algorithms with error mitigation, instead of the more difficult error correction, could tackle cutting-edge physics problems, such as understanding the quantum properties of superconductors and novel electronic materials.
“We’re entering the regime where the quantum computer might be able to do things that current algorithms on classical computers cannot do,” said UC Berkeley graduate student and study co-author Sajant Anand.