Expanding possibilities of quantum state engineering and amplifying optical Schrodinger kitten state

Abstract

We demonstrate an optical method to engineer optical Schr\"odinger cat states (SCSs) of large size beta ranging from beta=2 to beta=3 with high fidelity close to 0.99. Our approach uses the alpha-representation of the SCSs in infinite Hilbert space with base in terms of displaced number states characterized by the displacement amplitude alpha. An arbitrary alpha-representation of SCSs enables manipulation of the amplitudes in wider ranges of parameters, greatly expanding the possibilities for generation of desired nonclassical states. The optical scheme we consider is quite universal for implementation of the conditioned states close to SCSs with use of linear-optics elements and detectors projecting unitarily transformed input states onto the target one. Different states (e.g., number state or coherent state or superposed state) are selected as the input to the optical scheme. In particular, an input small-size Schroodinger kitten state can give rise to an output large-size SCS.