Spin squeezing generated by the anisotropic central spin model

Abstract: Spin squeezing, as a crucial quantum resource, plays a pivotal role in quantum metrology, enabling us to achieve high-precision parameter estimation schemes. Here we investigate the spin squeezing and the quantum phase transition in an anisotropic central spin system. We find that this kind of central spin systems can be mapped to the anisotropic Lipkin-Meshkov-Glick model in the limit where the ratio of transition frequencies between the central spin and the spin bath tends towards infinity. This property can induce a one-axis twisting interaction and provides a new possibility for generating spin squeezing. We separately consider generating spin-squeezed states via the ground state and the dynamic evolution of the central spin model. The results show that the spin squeezing parameter improves as the anisotropy parameter decreases, and its value scales with system size as $N^{-2/3}$. Furthermore, we obtain the critical exponent of the quantum Fisher information around the critical point by numerical simulation, and find its value tends to $4/3$ as the frequency ratio and the system size approach infinity. This work offers a promising scheme for generating spin-squeezed state and paves the way for potential advancements in quantum sensing.