Quantum Fisher information and spin squeezing in one-axis twisting model

Abstract

Abstract. We consider the quantum Fisher information and spin squeezing in oneaxis twisting model with a coherent spin state |θ 0 , φ 0 . We analytically discuss the dependence of the two parameters: spin squeezing parameter ξ 2 K and the average parameter estimation precision χ 2 on the polar angle θ 0 and the azimuth angle φ 0 . Moreover, we discuss the effects of the collisional dephasing on the dynamics of the two parameters. In this case, the analytical solution of ξ 2 K is also obtained.

Even- and odd-orthogonality properties of the Wigner D-matrix and their metrological applications

“…Note that, in the setting as mentioned above, the QFIs for the states before and after the second beams splitter are identical due to the invariance property of the QFI under a phase-independent unitary evolution [18,19]. We below take the CFI and QFI as the two figure of merits, as they are widely used to evaluate the performance of various metrological applications [25,26,27,28,29,30,15,14,31,32,33,34,35,36]. Hence, an efficient way to identify a measurement being optimal for a quantum phase estimation task is to test whether the QFI and the CFI with respect to a specific measurement are identical [23,37].…”

Pairwise Quantum Discord for a Symmetric Multi-Qubit System in Different Types of Noisy Channels

“…( 1). The elements of the two-quibt reduced density matrix can be represented by the local expectation values for the one-axis twisting state [28][29][30][34][35][36][37][38][39][40]…”

“…Motivated from the recent study on the dynamics of QD and GMQD under the influence of external environments for different multipartite states [33], such as Werner-GHZ type three-qubit and six-qubit states, we here devote to examining the pairwise quantum correlation properties in terms of QD for pairs of particles extracted from a symmetric state. The two-particle density matrix is expressed in terms of expectation values of collective spin operators S for the large system [28][29][30][34][35][36][37][38][39][40].…”

Generation and storage of spin squeezing via learning-assisted optimal control

“…Kitagawa and Ueda [9] further proposed two different mechanisms, one-and two-axis twisting models, for the * liujingphys@hust.edu.cn generation of spin squeezed states. The one-axis twisting (OAT) model [16][17][18][19][20][21] can provide a precision limit at the scaling N −2/3 (N is the particle number) and the two-axis twisting (TAT) model [22][23][24][25][26][27][28] provides a better scaling N −1 . These advantages motivate the scientists to try to realize these models in experiments.…”