Monika Bartkowiak, Lian-Ao Wu, Adam Miranowicz
The idea of using Kerr nonlinear media to perform quantum information processing with photons as qubits sounds promising. It provides, in particular, the possibility of having deterministic implementations of two-qubit entangling gates contrary to solely probabilistic implementations of such gates based on linear optics. Unfortunately, phase shifts induced by the Kerr effect are usually very small at the single-photon level. We propose two circuits for enhancing the cross-Kerr phase shift by applying one- and two-mode quadrature squeeze operators. Our results are based on the vector coherent state theory and can be implemented by physical operations satisfying the commutation relations for generators of the generalized special unitary group SU(1,1). While the proposed methods can be useful for realization of quantum optical entangling gates based on Kerr nonlinear media at the single-photon level, they also indicate a general alternative approach to enhance higher-order nonlinearities by applying lower-order nonlinear effects.
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http://arxiv.org/abs/1210.2384
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