We observe spin squeezing in three-component Bose gases where all three hyperfine states are coupled by synthetic spin-orbit coupling. This phenomenon is a direct consequence of spin-orbit coupling, as can be seen clearly from an effective spin Hamiltonian. By solving this effective model analytically with the aid of a Holstein-Primakoff transformation for a spin-1 system in the low excitation limit, we conclude that the spin-nematic squeezing, a category of spin squeezing existing exclusively in large spin systems, is enhanced with increasing spin-orbit coupling intensity and effective Zeeman field, which correspond to Rabi frequency ${\mathrm{\ensuremath{\Omega}}}_{R}$ and two-photon detuning $\ensuremath{\delta}$ within the Raman scheme for synthetic spin-orbit coupling, respectively. These trends of dependence are in clear contrast to spin-orbit-coupling-induced spin squeezing in spin-1/2 systems. We also analyze the effects of harmonic trap and interparticle interaction with realistic experimental parameters numerically, and find that a strong harmonic trap favors spin-nematic squeezing. We further show spin-nematic squeezing can be interpreted as two-mode entanglement or two-spin squeezing at low excitation. Our findings can be observed in $^{87}\mathrm{Rb}$ gases with existing techniques of synthetic spin-orbit coupling and spin-selective imaging.We observe spin squeezing in three-component Bose gases where all three hyperfine states are coupled by synthetic spin-orbit coupling. This phenomenon is a direct consequence of spin-orbit coupling, as can be seen clearly from an effective spin Hamiltonian. By solving this effective model analytically with the aid of a Holstein-Primakoff transformation for a spin-1 system in the low excitation limit, we conclude that the spin-nematic squeezing, a category of spin squeezing existing exclusively in large spin systems, is enhanced with increasing spin-orbit coupling intensity and effective Zeeman field, which correspond to Rabi frequency ${\mathrm{\ensuremath{\Omega}}}_{R}$ and two-photon detuning $\ensuremath{\delta}$ within the Raman scheme for synthetic spin-orbit coupling, respectively. These trends of dependence are in clear contrast to spin-orbit-coupling-induced spin squeezing in spin-1/2 systems. We also analyze the effects of harmonic trap and interparticle interaction with realistic experimental parameters numerically, and find that a strong harmonic trap favors spin-nematic squeezing. We further show spin-nematic squeezing can be interpreted as two-mode entanglement or two-spin squeezing at low excitation. Our findings can be observed in $^{87}\mathrm{Rb}$ gases with existing techniques of synthetic spin-orbit coupling and spin-selective imaging.

arXiv:1609.03141Physical Review AJan 4, 201715 citations

Spin–orbit coupling in quantum gases

Victor M. Galitski, Ian B. Spielman

arXiv:1312.3292NatureFeb 5, 2013963 citations

Spin–orbit coupling induced three-dimensional topological objects in attractive Bose–Einstein condensates

Liang-Liang Xu, Yong-Kai Liu, Shi-Jie Yang

Attractive Bose-Einstein condensates of dilute alkali gases are unstable against collapse in two- and three-dimensional free space. Nevertheless, we demonstrate that the spin-orbit coupling of the two-component condensates counteracts the tendency of collapse and makes the system preferable to an extended spatial distribution in the three-dimensional case. Furthermore, stable topological objects can be formed in the condensates, which are shown to be the lowest energy states. Two configurations of the density profiles, called three-dimensional skyrmion and three-dimensional dimeron, respectively, are identified depending on the strength of the spin-orbit coupling.Attractive Bose-Einstein condensates of dilute alkali gases are unstable against collapse in two- and three-dimensional free space. Nevertheless, we demonstrate that the spin-orbit coupling of the two-component condensates counteracts the tendency of collapse and makes the system preferable to an extended spatial distribution in the three-dimensional case. Furthermore, stable topological objects can be formed in the condensates, which are shown to be the lowest energy states. Two configurations of the density profiles, called three-dimensional skyrmion and three-dimensional dimeron, respectively, are identified depending on the strength of the spin-orbit coupling.

Journal of Physics Condensed MatterMar 9, 20181 citation

Quantum Spin Dynamics in Spin-orbit Coupled Bose Gas

Wai Ho Tang, Shizhong Zhang

Bulletin of the American Physical SocietyMar 6, 20180 citations

^{87}\mathrm{Rb}

gases with existing techniques of synthetic spin-orbit coupling and spin-selective imaging.