Rapid and Unconditional Parametric Reset Protocol for Tunable Superconducting Qubits

TL;DR

This paper introduces a rapid, high-fidelity, and unconditional reset protocol for superconducting qubits that avoids complex calibration and crosstalk, significantly improving qubit initialization speed and efficiency.

Contribution

The authors present a flux modulation-based swap method for qubit reset that is fast, scalable, and does not require additional chip architecture or feedback mechanisms.

Findings

Achieves 0.08% excited state population within 34 ns

Suppresses second excited state effectively

Minimal impact on neighboring qubits

Abstract

Qubit initialization is a critical task in quantum computation and communication. Extensive efforts have been made to achieve this with high speed, efficiency and scalability. However, previous approaches have either been measurement-based and required fast feedback, suffered from crosstalk or required sophisticated calibration. Here, we report a fast and high-fidelity reset scheme, avoiding the issues above without any additional chip architecture. By modulating the flux through a transmon qubit, we realize a swap between the qubit and its readout resonator that suppresses the excited state population to 0.08% $\pm$ 0.08% within 34 ns (284 ns if photon depletion of the resonator is required). Furthermore, our approach (i) can achieve effective second excited state depletion, (ii) has negligible effects on neighbouring qubits, and (iii) offers a way to entangle the qubit with an itinerant single photon, useful in quantum communication applications.