Preparing squeezed, cat and GKP states with parity measurements

TL;DR

This paper introduces a protocol using displaced parity measurements for preparing various bosonic quantum states, including squeezed, cat, and GKP states, demonstrating high squeezing levels and robustness against imperfections.

Contribution

The authors propose a new measurement-based protocol for preparing diverse bosonic states, extending existing methods with improved squeezing and state versatility.

Findings

Achieved up to ~9 dB of squeezing after three measurements

Protocol is robust against experimental imperfections

Generalized to prepare cat and GKP states

Abstract

Bosonic modes constitute a central resource in a wide range of quantum technologies, providing long-lived degrees of freedom for the storage, processing, and transduction of quantum information. Such modes naturally arise in platforms including circuit quantum electrodynamics, quantum acoustodynamics, and trapped-ion systems. In these architectures, coherent control and high-fidelity readout of the bosonic degrees of freedom are achieved via coupling to an auxiliary qubit. When operated in the strong dispersive regime, this interaction enables parity measurements of the mode which, in combination with phase-space displacements, constitute a standard experimental tool for full Wigner-function tomography. Here, we propose a protocol based on displaced parity measurements that allows for the preparation of a variety of bosonic quantum states. As a first example, we demonstrate the generation of squeezed states, achieving up to ~9 dB of squeezing after only three parity measurements, and show that the protocol is robust against experimental imperfections. Finally, we generalize our approach to the preparation of other paradigmatic bosonic states, including cat and Gottesman-Kitaev-Preskill states.