Fast and Unconditional All-Microwave Reset of a Superconducting Qubit

TL;DR

This paper presents a fast, unconditional microwave-based reset method for superconducting transmon qubits that reinitializes the system to its ground state in under 500 ns without feedback, enhancing quantum error correction.

Contribution

It introduces a novel microwave-induced reset protocol for transmon qubits that operates without feedback and is compatible with existing readout architectures.

Findings

Achieves 0.2% residual excitation after reset

Resets system to ground state in less than 500 ns

Does not require feedback or architecture modifications

Abstract

Active qubit reset is a key operation in many quantum algorithms, and particularly in error correction codes. Here, we experimentally demonstrate a reset scheme of a three level transmon artificial atom coupled to a large bandwidth resonator. The reset protocol uses a microwave-induced interaction between the $|f,0\rangle$ and $|g,1\rangle$ states of the coupled transmon-resonator system, with $|g\rangle$ and $|f\rangle$ denoting the ground and second excited states of the transmon, and $|0\rangle$ and $|1\rangle$ the photon Fock states of the resonator. We characterize the reset process and demonstrate reinitialization of the transmon-resonator system to its ground state with $0.2\%$ residual excitation in less than $500 \, \rm{ns}$. Our protocol is of practical interest as it has no requirements on the architecture, beyond those for fast and efficient single-shot readout of the transmon, and does not require feedback.