Exact results for Schrödinger cats in driven-dissipative systems and their feedback control.

Fabrizio Minganti,Nicola Bartolo,Cristiano Ciuti,Jared Lolli,Wim Casteels

doi:10.1038/srep26987

Fabrizio Minganti, Nicola Bartolo + Show 3 more

Open Access

https://doi.org/10.1038/srep26987

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Abstract

In quantum optics, photonic Schrödinger cats are superpositions of two coherent states with opposite phases and with a significant number of photons. Recently, these states have been observed in the transient dynamics of driven-dissipative resonators subject to engineered two-photon processes. Here we present an exact analytical solution of the steady-state density matrix for this class of systems, including one-photon losses, which are considered detrimental for the achievement of cat states. We demonstrate that the unique steady state is a statistical mixture of two cat-like states with opposite parity, in spite of significant one-photon losses. The transient dynamics to the steady state depends dramatically on the initial state and can pass through a metastable regime lasting orders of magnitudes longer than the photon lifetime. By considering individual quantum trajectories in photon-counting configuration, we find that the system intermittently jumps between two cats. Finally, we propose and study a feedback protocol based on this behaviour to generate a pure cat-like steady state.

Highlights

In quantum optics, photonic Schrödinger cats are superpositions of two coherent states with opposite phases and with a significant number of photons
We show that the rich transient dynamics depends dramatically on the initial state
The unique steady state appears to be a mixture of two orthogonal cat states of opposite parity

Summary

Introduction

Photonic Schrödinger cats are superpositions of two coherent states with opposite phases and with a significant number of photons. These states have been observed in the transient dynamics of driven-dissipative resonators subject to engineered two-photon processes. We show that the rich transient dynamics depends dramatically on the initial state It can exhibit metastable plateaux lasting several orders of magnitude longer than the single-photon lifetime. For a wide range of parameters around typical experimental ones[21], the unique steady-state density matrix has as eigenstates two cat-like states even for significant one-photon losses, with all the other eigenstates having negligible probability

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