Faster technique for resetting quantum circuits proposed

A fridge that holds qubits. The Center for Quantum Computing is a part of the RIKEN.

Rebooting a quantum computer is a difficult process that can damage its parts, but now two physicists have proposed a fast and controllable way to hit reset.

Conventional computers process information in bits that are either zero or one. The potential power of quantum computers lies in their ability to process qubits that can take a value of zero or one at the same time.

To reuse the same circuit for multiple operations, you have to force the qubits back to zero fast. It is more difficult to say that is done.

One of the best ways to reset a qubit is to link it to a photon in a tiny device called a resonator. After the photon in the resonator decays, the energy from the qubit is released into the environment. The qubit state is dropped back to the ground state. The problem with this method is that permanent entanglement to a decaying photon degrades the qubit's quality so quickly that it ceases to be useful for future operations. It's bad for the qubit, whose lifetime becomes short.

Tsai and his colleague, Teruaki Yoshioka, have created a simulation to help find a better way to reset the qubit.

The pair proposed building a resonator that can be controlled using an additional junction made by sandwiching a superconducting material with a normal metal and another superconductor. The junction is controlled by a voltage. The set-up is adjusted so that the photon can't decay. When the operation is done, the physicists change the voltage to allow the photon to release energy. The key to our proposal is theadjustable resonator.

The best lab record for reseting a qubit is 280 seconds. The simulations suggest we could reset the qubit in 80 seconds.

The set-up is being tested with promising results by the team. If we can use it in a quantum circuit, it should be very useful.

The research was published.

T. Yoshioka and his team have a paper on Fast unconditional initialization for superconducting qubit and resonator using quantum-circuit refrigerator. There is a DOI: 10.1063/5.0057894.

The Applied Physics Letters is a journal.

There is a proposal for a faster technique for resetting quantum circuits.

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