Fast readout and reset of a superconducting qubit coupled to a resonator with an intrinsic Purcell filter

TL;DR

This paper introduces an intrinsic Purcell filter leveraging a multi-mode resonator to significantly suppress qubit decay, enabling fast, high-fidelity readout and reset of superconducting qubits.

Contribution

The authors demonstrate a novel intrinsic Purcell filter that suppresses qubit decay, allowing for rapid and high-fidelity qubit readout and reset.

Findings

Suppression of qubit decay exceeds 100x over 600 MHz bandwidth

Achieved 40-ns qubit readout with 99.1% fidelity

Achieved 100-ns qubit reset with less than 1.7% residual excitation

Abstract

Coupling a resonator to a superconducting qubit enables various operations on the qubit, including dispersive readout and unconditional reset. The speed of these operations is limited by the external decay rate of the resonator. However, increasing the decay rate also increases the rate of qubit decay via the resonator, limiting the qubit lifetime. Here, we demonstrate that the resonator-mediated qubit decay can be suppressed by utilizing the distributed-element, multi-mode nature of the resonator. We show that the suppression exceeds two orders of magnitude over a bandwidth of 600 MHz. We use this "intrinsic Purcell filter" to demonstrate a 40-ns readout with 99.1% fidelity and a 100-ns reset with residual excitation of less than 1.7%.