How to Fix Quantum Computing Bugs

Tue, 19 Apr 2022 06:15:00 GMT
Scientific American - Technology

The same physics that makes quantum computers powerful also makes them finicky. New techniques aim...

Quantum computers suffer types of errors that are unknown to classical computers and that our standard correction techniques cannot fix.

Besides having errors in flipped bits, in a quantum computer you also have errors in the phases of the waves describing the states of the qubits.

To get around all these issues, quantum error correction strategies use helper qubits.

For quantum computers, errors arise when the device gets entangled with the environment.

Overlooking the need for universal computation is also the root of misconceptions and misleading messages about logical qubits and quantum error correction.

We can advance what we can do with noisy quantum computers using error mitigation.

Instead of trying to design a quantum circuit to fix errors in computations in real-time, error mitigation uses a classical computer to learn the contribution of noise from the outcome of noisy experiments and cancel it.

Our theory team recently showed that this method could, by using error correction for Clifford gates and error mitigation for non-Clifford gates, allow us to simulate universal quantum circuits without needing magic state distillation.

I'm proud to have played a role in shaping quantum computing from a field of lab-based demonstrations of one- and two-qubit devices to a field where anyone can access quantum systems with dozens of qubits via the cloud.

Reaping the benefits of quantum computing will require hardware that operates below the error threshold, error correction codes that can fix the remaining mishaps with as few additional qubits and gates as possible, and better ways to combine error correction and mitigation.

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