01386nas a2200193 4500008004100000245004800041210004700089260001500136520082300151100002300974700002300997700002101020700002101041700002401062700002501086700002701111700001701138856003701155 2018 eng d00aPhoton Subtraction by Many-Body Decoherence0 aPhoton Subtraction by ManyBody Decoherence c2018/03/133 a

We present an experimental and theoretical investigation of the scattering-induced decoherence of multiple photons stored in a strongly interacting atomic ensemble. We derive an exact solution to this many-body problem, allowing for a rigorous understanding of the underlying dissipative quantum dynamics. Combined with our experiments, this analysis demonstrates a correlated coherence-protection process, in which the induced decoherence of one photon can preserve the spatial coherence of all others. We discuss how this effect can be used to manipulate light at the quantum level, providing a robust mechanism for single-photon subtraction, and experimentally demonstrate this capability.

1 aMurray, Callum, R.1 aMirgorodskiy, Ivan1 aTresp, Christoph1 aBraun, Christoph1 aParis-Mandoki, Asaf1 aGorshkov, Alexey, V.1 aHofferberth, Sebastian1 aPohl, Thomas uhttps://arxiv.org/abs/1710.1004701559nas a2200157 4500008004100000245008500041210006900126260001500195300001100210490000700221520104000228100002301268700002501291700001701316856006801333 2016 eng d00aMany-body decoherence dynamics and optimised operation of a single-photon switch0 aManybody decoherence dynamics and optimised operation of a singl c2016/09/13 a0920010 v183 a

We develop a theoretical framework to characterize the decoherence dynamics due to multi-photon scattering in an all-optical switch based on Rydberg atom induced nonlinearities. By incorporating the knowledge of this decoherence process into optimal photon storage and retrieval strategies, we establish optimised switching protocols for experimentally relevant conditions, and evaluate the corresponding limits in the achievable fidelities. Based on these results we work out a simplified description that reproduces recent experiments [arXiv:1511.09445] and provides a new interpretation in terms of many-body decoherence involving multiple incident photons and multiple gate excitations forming the switch. Aside from offering insights into the operational capacity of realistic photon switching capabilities, our work provides a complete description of spin wave decoherence in a Rydberg quantum optics setting, and has immediate relevance to a number of further applications employing photon storage in Rydberg media. 

1 aMurray, Callum, R.1 aGorshkov, Alexey, V.1 aPohl, Thomas uhttp://iopscience.iop.org/article/10.1088/1367-2630/18/9/092001