Fast unconditional reset and leakage reduction in fixed-frequency transmon qubits

TL;DR

This paper presents a fast, unconditional reset and leakage reduction protocol for fixed-frequency transmon qubits, enhancing fault-tolerant quantum computing by reducing error rates and QEC cycle times.

Contribution

The authors introduce a novel protocol that efficiently resets and reduces leakage in fixed-frequency transmon qubits using tunable couplers, compatible with surface code architectures.

Findings

Reset and leakage reduction completed in 83ns

Achieved reset fidelities above 99%

Protocol reduces QEC cycle time and improves fidelity

Abstract

The realization of fault-tolerant quantum computing requires the execution of quantum error-correction (QEC) schemes, to mitigate the fragile nature of qubits. In this context, to ensure the success of QEC, a protocol capable of implementing both qubit reset and leakage reduction is highly desirable. We demonstrate such a protocol in an architecture consisting of fixed-frequency transmon qubits pair-wise coupled via tunable couplers -- an architecture that is compatible with the surface code. We use tunable couplers to transfer any undesired qubit excitation to the readout resonator of the qubit, from which this excitation decays into the feedline. In total, the combination of qubit reset, leakage reduction, and coupler reset takes only 83ns to complete. Our reset scheme is fast, unconditional, and achieves fidelities well above 99%, thus enabling fixed-frequency qubit architectures as future implementations of fault-tolerant quantum computers. Our protocol also provides a means to both reduce QEC cycle runtime and improve algorithmic fidelity on quantum computers.