Single-shot Readout of a Superconducting Qubit using a Josephson Parametric Oscillator

TL;DR

This paper introduces a novel single-shot readout method for superconducting qubits using a Josephson parametric oscillator, achieving high contrast and potential for quantum computing fidelity.

Contribution

The paper demonstrates a new dispersive readout technique employing a tunable Josephson parametric oscillator for improved qubit state discrimination.

Findings

Achieved high-contrast qubit state mapping with classical parametric oscillation.

Demonstrated proof-of-principle single-shot readout performance.

Indicated potential to surpass quantum computing fidelity thresholds.

Abstract

We propose and demonstrate a new read-out technique for a superconducting qubit by dispersively coupling it to a Josephson parametric oscillator. We employ a tunable quarter-wavelength superconducting resonator and modulate its resonant frequency at twice its value with an amplitude surpassing the threshold for parametric instability. We map the qubit states onto two distinct states of classical parametric oscillation: one oscillating state, with $185\pm15$ photons in the resonator, and one with zero oscillation amplitude. This high contrast obviates a following quantum-limited amplifier. We demonstrate proof-of-principle, single-shot readout performance, and present an error budget indicating that this method can surpass the fidelity threshold required for quantum computing.