Quantum metrology with entangled spin-coherent states of two modes

摘要

Recently, Gerry et al. [Phys. Rev. A 79, 022111 (2009)] studied the violation of the Bell-Clauser-Horne-nShimony-Holt inequality for two-spin systems, prepared in an entanglement of spin-coherent states, the so-callednentangled spin-coherent states (ESCSs), and found maximal violations for a large class of states. In this paper,nusing the Holstein-Primakoff realization (HPR) of angular momentum algebra, we present an improved phasenestimation scheme employing ESCSs and demonstrate that increasing the spin number gives the smallest variancenin the phase parameter in comparison to NOON states under perfect and lossy conditions. The phase sensitivitynof this interferometric scheme with parity detection on one of the output states is discussed.