Spin Squeezing in Spinor Condensates

Chris Hamley, Corey Gerving, Thai M. Hoang +1 more

Nikolaos Giovanoudis, Navid Kazemiseresht, Fabio Mezzacapo +2 more

The production of large-scale entangled states is one of the main goals of next-generation quantum technologies, with an immediate potential for applications in the context of entanglement-assisted quantum sensing. A very promising platform to achieve this goal is offered by ultracold spinor gases, made of atoms with a large internal spin sensitive to magnetic fields. Here we show that the native spin-changing collisions in a spinor Bose-Einstein condensate, combined with an arbitrary quadratic Zeeman shift, can generate scalable spin squeezing in the collective spin of the ensemble, following the universal paradigm of the celebrated one-axis-twisting model. Squeezing dynamics is driven by the quadratic Zeeman shift when this shift is small; and by the spin-changing collisions for large shifts, in the form of stroboscopic squeezing. Turning off the Zeeman shift freezes out the collective-spin dynamics, so that the ensuing collective spin dynamics can be uniquely governed by an external field to be sensed. Our theoretical results pave the way for the use of spinor Bose gases with a large spin in fundamental studies of entanglement, as well as in advanced metrological applications.

Özgür Esat Müstecaplıoğlu, Mei Zhang, Li You

We analyze quantum correlation properties of a spinor-1 $(f=1)$ Bose-Einstein condensate using the Gell-Mann realization of SU(3) symmetry. We show that previously discussed phenomena of condensate fragmentation and spin mixing can be explained in terms of the hypercharge symmetry. The ground state of a spinor-1 condensate is found to be fragmented for ferromagnetic interactions. The notion of two-bosonic-mode squeezing is generalized to the two-spin $(U\ensuremath{-}V)$ squeezing within the SU(3) formalism. Spin squeezing in the isospin subspace (T) is found and is numerically investigated. We also provide results for the stationary states of spinor-1 condensates.

Ding Xiong, Huang Guoqiang, Cui-Lan Luo

C. K. Law, H. T. Ng, P. T. Leung

We examine the spin-squeezing phenomena in a collection of interacting spins in the presence of an external field. We show that the combination of the external field and the nonlinear atom-atom interaction leads to a strong reduction of spin fluctuations that can be maintained in an extended period of time. Our results can be applied to achieve spin squeezing in a spinor Bose condensate.

Song-Song Li, Jiang Yan-hu, Zhenya Liu