RESUMO
Quantum memories are a crucial element toward efficient quantum protocols. In the continuous variables domain, such memories need to provide high fidelity with an efficiency set to one. Moreover, one needs to store complex quantum states exhibiting negative Wigner functions after storage. We report the storage of single- and two-photon Fock states in an all-optical quantum memory. The Wigner functions of these states show negativity after a storage time of several hundred nanoseconds. This is, to our knowledge, the first demonstration of the storage in the optical domain of non-Gaussian states with more than one photon, captured from an external source and characterized with homodyne detection.
RESUMO
We propose a feasible optical setup allowing for a loophole-free Bell test with efficient homodyne detection. A non-Gaussian entangled state is generated from a two-mode squeezed vacuum by subtracting a single photon from each mode, using beam splitters and standard low-efficiency single-photon detectors. A Bell violation exceeding 1% is achievable with 6 dB squeezed light and a homodyne efficiency around 95%. A detailed feasibility analysis, based upon the recent experimental generation of single-mode non-Gaussian states, suggests that this method opens a promising avenue towards a complete experimental Bell test.
RESUMO
We observed photon antibunching in the fluorescent light emitted from a single nitrogen-vacancy center in diamond at room temperature. The possibility of generating triggerable single photons with such a solid-state system is discussed.