title: Exact results for Schrödinger cats in driven-dissipative systems and their feedback control.
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.
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Matériaux et Phénomènes Quantiques, CNRS-UMR7162, 75013 Paris, France.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Minganti
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Matériaux et Phénomènes Quantiques, CNRS-UMR7162, 75013 Paris, France.
authors.forename: Nicola
authors.initials: N
authors.lastname: Bartolo
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Matériaux et Phénomènes Quantiques, CNRS-UMR7162, 75013 Paris, France.
authors.forename: Jared
authors.initials: J
authors.lastname: Lolli
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Matériaux et Phénomènes Quantiques, CNRS-UMR7162, 75013 Paris, France.
authors.forename: Wim
authors.initials: W
authors.lastname: Casteels
authors.affiliation: Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Matériaux et Phénomènes Quantiques, CNRS-UMR7162, 75013 Paris, France.
authors.forename: Cristiano
authors.initials: C
authors.lastname: Ciuti
mesh_terms: D003198:Computer Simulation; D005246:Feedback; D017711:Nonlinear Dynamics; D055095:Optics and Photonics / Q000706:statistics & numerical data*; D017785:Photons; D011789:Quantum Theory