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arXiv · 1601.02861

Exact results for Schr\"odinger cats in driven-dissipative systems and their feedback control

F. Minganti·N. Bartolo·J. Lolli·W. Casteels·C. Ciuti
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Abstract

In quantum optics, photonic Schr\"odinger 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.

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F. Minganti, N. Bartolo, J. Lolli, W. Casteels, C. Ciuti. 2016-01-12. Exact results for Schr\"odinger cats in driven-dissipative systems and their feedback control. https://doi.org/10.1038/srep26987

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