Related papers: Three-Axis Spin Squeezed States Associated with Excited-State Quantum Phase Transitions

Three-Axis Spin Squeezed States Associated with Excited-State Quantum Phase Transitions

URL: http://arxiv.org/abs/2512.24472v1
Date: Tue, 30 Dec 2025 21:36:32 GMT
Title: Three-Axis Spin Squeezed States Associated with Excited-State Quantum Phase Transitions
Authors: Chon-Fai Kam,
Abstract summary: We introduce a class of three-axis spin squeezed states within the anisotropic Lipkin-Meshkov-Glick model.<n>We analyze the structure and metrological properties of the resulting states.<n>These results unify spin squeezing, quantum criticality, and rotor analogies, and suggest implementations in Rydberg arrays and cavity-QED platforms.
Score: 0.0
License: http://creativecommons.org/licenses/by/4.0/
Abstract: Spin squeezing in collective atomic ensembles enables quantum-enhanced metrology by reducing noise below the standard quantum limit through nonlinear interactions. Extending the one-axis and two-axis twisting paradigms of Kitagawa and Ueda, we introduce a general class of three-axis spin squeezed states within the anisotropic Lipkin-Meshkov-Glick model. The model features direction-dependent quadratic couplings that interpolate between uniaxial and biaxial regimes and can be interpreted as an asymmetric quantum rotor. Using semiclassical dynamics, Majorana representations, and Husimi-Q distributions, we analyze the structure and metrological properties of the resulting states. The three-axis framework reproduces the known N^(-2/3) scaling of one-axis twisting and the Heisenberg-limited N^(-1) scaling of two-axis twisting, while allowing additional tunability and enhanced entanglement generation in low-spin systems. We further show that tuning the anisotropy parameters induces ground-state and excited-state quantum phase transitions, including a second-order transition associated with level clustering and critical dynamics. These results unify spin squeezing, quantum criticality, and rotor analogies, and suggest implementations in Rydberg arrays and cavity-QED platforms for precision sensing and quantum simulation.

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