Parity-dependent State Engineering and Tomography in the ultrastrong coupling regime

TL;DR

This paper introduces a parity symmetry-based method for controlling and reconstructing quantum states in the ultrastrong light-matter coupling regime, overcoming previous control limitations with minimal resources.

Contribution

It presents a novel protocol leveraging parity conservation and an ancillary qubit to enable state engineering and tomography in the USC regime.

Findings

Enables arbitrary state generation in USC regime

Provides a minimal-resource control protocol

Facilitates quantum state tomography in USC

Abstract

Reaching the strong coupling regime of light-matter interaction has led to an impressive development in fundamental quantum physics and applications to quantum information processing. Latests advances in different quantum technologies, like superconducting circuits or semiconductor quantum wells, show that the ultrastrong coupling regime (USC) can also be achieved, where novel physical phenomena and potential computational benefits have been predicted. Nevertheless, the lack of effective decoupling mechanism in this regime has so far hindered control and measurement processes. Here, we propose a method based on parity symmetry conservation that allows for the generation and reconstruction of arbitrary states in the ultrastrong coupling regime of light-matter interactions. Our protocol requires minimal external resources by making use of the coupling between the USC system and an ancillary two-level quantum system.