Squeezing the limit: quantum benchmarks for the teleportation and storage of squeezed states
M Owari, M B Plenio, E S Polzik, A Serafini, M M Wolf · New Journal of Physics · 2008
E-mail: mail Abstract. We derive fidelity benchmarks for the quantum storage and teleportation of squeezed states of continuous variable systems, for input ensembles where the degree of squeezing s is fixed, no information about its orientation in phase space is given, and the distribution of phase space displacements is a Gaussian. In the limit where the latter becomes flat, we prove analytically that the maximal classical achievable fidelity (which is 1/2 without squeezing, for s = 1) is given by √ s/(1 + s), vanishing when the degree of squeezing diverges. For mixed states, as well as for general distributions of displacements, we reduce the determination of the benchmarks to the solution of a finite-dimensional semidefinite program, which yields accurate, certifiable bounds thanks to a rigorous analysis of the truncation error. This approach may be easily adapted to more general ensembles of input states. PACS numbers: 03.67.Hk,03.65.Ta,42.50.Dv