Controlled-squeeze gate in superconducting quantum circuits

TL;DR

This paper introduces a controlled-squeeze gate in superconducting circuits that enables the creation of non-classical microwave states, facilitating quantum error detection and universal quantum operations with current technology.

Contribution

It proposes a novel controlled-squeeze gate mechanism in circuit QED, expanding the toolkit for quantum state engineering and bosonic code implementation.

Findings

The controlled-squeeze gate is feasible with current circuit QED technology.

It enables mapping qubit states into superpositions of squeezed states.

The approach allows for non-demolition parity measurements for photon loss detection.

Abstract

We present a method to prepare non-classical states of the electromagnetic field in a microwave resonator. It is based on a controlled gate that applies a squeezing operation on a SQUID-terminated resonator conditioned on the state of a dispersively coupled qubit. This controlled-squeeze gate, when combined with Gaussian operations on the resonator, is universal. We explore the use of this tool to map an arbitrary qubit state into a superposition of squeezed states. In particular, we target a bosonic code with well-defined superparity which makes photon losses detectable by non-demolition parity measurements. We analyze the possibility of implementing this using state-of-the-art circuit QED tools and conclude that it is within reach of current technologies.