Design of an optimal quantum receiver for interferometric sensing devices
Masahiro Takeoka, Masahide Sasaki, Masashi Ban · 2003
A practically realizable detection scheme that corresponds to the optimal measurement strategy within the Neyman-Pearson approach is proposed. The pure state probe field is generally described by | /spl psi//sub 0/> = U/spl circ/|0>, where U/spl circ/ is the unitary operator that defines the quantum property of the probe field. The prepared probe field is incident into the black box in which the unitary perturbative operation U/spl circ//sub p/(g) sometimes occurs, where g is the small parameter, such as the small phase shift, to be detected. The output field (|/spl psi//sub 0/> or |/spl psi//sub 1/> = U/spl circ//sub p/(g) |/spl psi//sub 0/> ) is then measured by the positive operator-valued measure (POVM) which consists of the reverse process of the preparation of the probe field and the photodetection process that discriminates if the field includes zero or non-zero photons. This is an application of the Kennedy detection scheme which has been considered as the detector for a binary communications system. The detection probability of the scheme is given by P/sub d/ = 1-||/sup 2/ that is what expected from the mathematical optimization procedure of the Neyman-Pearson hypothesis testing. The scheme is easily applicable to various quantum states such as the coherent or the squeezed probe fields, and so on.