Rapid high-fidelity multiplexed readout of superconducting qubits

TL;DR

This paper demonstrates a rapid, high-fidelity multiplexed readout of five superconducting qubits within 80 ns pulses, achieving 97% accuracy, crucial for scalable quantum computing.

Contribution

The authors introduce a fast, multiplexed readout scheme with individual Purcell filters, significantly improving speed and fidelity for multi-qubit measurements.

Findings

Achieved 97% correct assignment probability for five qubits.

Readout pulse length of 80 ns with resonator population under 250 ns.

Purcell filters effectively suppress off-resonant driving and qubit dephasing.

Abstract

The duration and fidelity of qubit readout is a critical factor for applications in quantum information processing as it limits the fidelity of algorithms which reuse qubits after measurement or apply feedback based on the measurement result. Here we present fast multiplexed readout of five qubits in a single 1.2 GHz wide readout channel. Using a readout pulse length of 80 ns and populating readout resonators for less than 250 ns we find an average correct assignment probability for the five measured qubits to be $97\%$. The differences between the individual readout errors and those found when measuring the qubits simultaneously are within $1\%$. We employ individual Purcell filters for each readout resonator to suppress off-resonant driving, which we characterize by the dephasing imposed on unintentionally measured qubits. We expect the here presented readout scheme to become particularly useful for the selective readout of individual qubits in multi-qubit quantum processors.