We examine the effect of the phase of the external light fields on the dynamics of spin fluctuations in a coupled two-component Bose–Einstein condensates. We discover that the phase of the coherent coupling between the two components to be an easily tunable experimental parameter that can conveniently manipulate the spin squeezing in our given system.

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Spin squeezing in open Heisenberg spin chains

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Quantum Information and Computation

Spin squeezing of one-axis twisting model in the presence of phase dephasing

JiChen-Gang, LiuYong-Chun, JinGuang-Ri

Published Mar 1, 2013• 0 citations

Publisher

Abstract

DOI: 10.5555/2481602.2481609

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Spin squeezing protocols successfully generate entangled many-body quantum states, the key pillars of the second quantum revolution. In our recent work [Phys. Rev. Lett. 129, 090403 (2022)] we showed that spin squeezing described by the one-axis twisting model can be generated in the Heisenberg spin- $1/2$ chain with periodic boundary conditions when accompanied by a position-dependent spin-flip coupling induced by a single laser field. In this work, we show analytically that the change in boundary conditions from the periodic to the open ones significantly modifies spin squeezing dynamics. A broad family of twisting models can be simulated by the system in the weak-coupling regime, including one- and two-axis twisting under specific conditions, providing the Heisenberg level of squeezing and acceleration of the dynamics. Our analytical findings are confirmed by full numerical simulations.Spin squeezing protocols successfully generate entangled many-body quantum states, the key pillars of the second quantum revolution. In our recent work [Phys. Rev. Lett. 129, 090403 (2022)] we showed that spin squeezing described by the one-axis twisting model can be generated in the Heisenberg spin-$1/2$ chain with periodic boundary conditions when accompanied by a position-dependent spin-flip coupling induced by a single laser field. In this work, we show analytically that the change in boundary conditions from the periodic to the open ones significantly modifies spin squeezing dynamics. A broad family of twisting models can be simulated by the system in the weak-coupling regime, including one- and two-axis twisting under specific conditions, providing the Heisenberg level of squeezing and acceleration of the dynamics. Our analytical findings are confirmed by full numerical simulations.

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|\theta_{0}, \phi_0\rangle

with the polar angle

\theta_0=\pi/2

. If the dephasing rate

\gamma\ll S^{-1/3}

, where

S

is total atomic spin, we find that the smallest value of squeezing parameter (i.e., the strongest squeezing) obeys the same scaling with the ideal one-axis twisting case, namely

\xi^2\propto S^{-2/3}

. While for a moderate dephasing, the achievable squeezing obeys the power rule

S^{-2/5}

, which is slightly worse than the ideal case. When the dephasing rate

\gamma>S^{1/2}

, we show that the squeezing is weak and neglectable.

^{87}\mathrm{Rb}

and

^{23}\mathrm{Na}

in the absence of the SOC. We confirm the spin squeezing by carrying out a fully beyond-mean-field numerical calculation using the truncated Wigner method. Additionally, the experimental implementation is also discussed.

1/2

chain with periodic boundary conditions when accompanied by a position-dependent spin-flip coupling induced by a single laser field. In this work, we show analytically that the change in boundary conditions from the periodic to the open ones significantly modifies spin squeezing dynamics. A broad family of twisting models can be simulated by the system in the weak-coupling regime, including one- and two-axis twisting under specific conditions, providing the Heisenberg level of squeezing and acceleration of the dynamics. Our analytical findings are confirmed by full numerical simulations.