Harnessing two-photon dissipation for enhanced quantum measurement and control

TL;DR

This paper explores how engineered two-photon dissipation in superconducting devices enhances quantum measurement, control, and state preparation, including overcoming Wigner tomography limitations, implementing universal gates, and generating highly squeezed cat states.

Contribution

It demonstrates novel applications of strong two-photon dissipation beyond cat qubit stabilization, such as improved tomography, universal gate realization, and advanced state engineering.

Findings

Overcomes high-photon-number Wigner tomography limitations

Enables universal gates on cat qubits

Prepares squeezed cat states with >3.96 dB squeezing

Abstract

Dissipation engineering offers a powerful tool for quantum technologies. Recently, new superconducting devices have achieved an engineered two-photon dissipation rate exceeding all other relevant timescales. In particular, they have proven most useful in preventing transitions between the logical states $|\pm\alpha\rangle$ of a cat qubit. Here, we present three key applications of strong two-photon dissipation for quantum measurement and control, beyond cat qubit stabilization. Firstly, we demonstrate its efficacy in overcoming limitations encountered in Wigner tomography at high photon numbers. Secondly, we showcase its potential for realizing universal gates on cat qubits, exploiting the coherent mapping between cat qubit states and superpositions of 0 and 1 photons. Finally, we harness the transient dynamics of a cat state under two-photon dissipation to prepare squeezed cat states with a squeezing factor exceeding 3.96$\pm$0.07 dB.