Scheme for entangling atom-photon pairs via an input light in superposition state

Vladan Vuletić

戴启润, Jiqing Fu, 景辉

We propose a feasible scheme to create macroscopically entangled atom-photon pairs by preparing an input optical superposition state.Several interesting non-classical quantum statistical effects like the atomic squeezed effects are clearly demonstrated.The making and manipulation of entangled atom-photon pairs are useful for, e.g., high-precision interferometry and quantum information science.

Federica A. Beduini, Joanna A. Zielińska, Vito Giovanni Lucivero +1 more

Dmitry A. Kalashnikov, V. P. Karasev, Konstantin G. Katamadze +2 more

We consider a new method for the generation of polarization-frequency entangled states of photon pairs. We use a frequency-nondegenerate regime of spontaneous parametric down conversion where the photon pairs (biphotons) are produced with identical polarizations, propagate mostly in the same direction, but differ in frequency. Entanglement is achieved by a coherent superposition of pairs emitted from two nonlinear crystals, with the polarization of the biphotons from the first crystal being changed by a transformer placed between the two crystals. We show that this scheme allows the degree of entanglement to be controlled by the choice of biphoton frequencies.

Joerg Bochmann, B. Weber, Holger Specht +6 more

Akihiro Yamaguchi, Holger Friedrich Hofmann

Well-controlled nonlinear interactions between light-field pulses and single atoms could be used to implement optical quantum information technologies based on qubits encoded in superpositions of coherent states of light. Here, we investigate the transformation of a coherent light field input at a single atom sufficiently far from resonance to limit the decoherence effects associated with random excitations of the atom. The conditions for suppressing multiphoton scattering to implement arbitrarily large shifts of the coherent light amplitude without decoherence are studied. It is shown that quantum-controlled coherent shifts can be achieved by sufficiently long coherent pulses, indicating the possibility of generating superpositions of coherent states with large amplitude differences. The dominant multiphoton scattering effect associated with four-wave mixing is also identified, and the spectral and temporal characteristics of the entangled photon pairs generated by this process are discussed.