Isotropic and squeezed fluctuations in ann-qubit system
C Muñoz, A. B. Klimov · Journal of Physics A Mathematical and Theoretical · 2011
We show that 2 n discrete coherent states of an n -qubit system, generated by application of the discrete displacement operators to a symmetric fiducial state, have isotropic fluctuations, with n /2 ⩽ 〈Δ S 2 〉 ⩽ n , in a specific tangent plane, which in general is not orthogonal to the mean spin direction. This allows us to use them as reference states to define a discrete squeezing for non-symmetric n -qubit states. Examples of states with reduced fluctuations, obtained after application of XOR gates to correlate (partially entangle) qubits, are analyzed.