The dynamics of quantum phases in a spin-1 condensate

Yixiao Huang, Yi Ding, Jiahao Xu +3 more

We study spin-nematic squeezing in a spinor Bose-Einstein condensate and use it to probe dynamical quantum phase transitions. We show that the quench dynamics of the spin-nematic squeezing exhibits a nonanalytical change with respect to a final quadratic Zeeman energy, and demonstrate that the squeezing detects not only the ground state phase diagram, but also the excited state quantum phase transition. We further analyze the dynamic stabilization of the system and present its relation to the dynamical quantum phase transitions. Our results are applicable to the spinor condensates with both of the sodium and rubidium atoms.

Ralph Dum

Yingmei Liu, Sebastian Jung, Stephen Maxwell +3 more

Condensates of spin-1 sodium display rich spin dynamics due to the antiferromagnetic nature of the interactions in this system. We use Faraday rotation spectroscopy to make a continuous and minimally destructive measurement of the dynamics over multiple spin oscillations on a single evolving condensate. This method provides a sharp signature to locate a magnetically tuned separatrix in phase space which depends on the net magnetization. We also observe a phase transition from a two- to a three-component condensate at a low but finite temperature using a Stern-Gerlach imaging technique. This transition should be preserved as a zero-temperature quantum phase transition.

M.-S. Chang, Qishu Qin, Wenxian Zhang +2 more

Fulin Deng, Peng Xu, Su Yi +1 more

Abstract Multiple quantum coherences are often employed to describe quantum many-body dynamics in nuclear spin systems and recently, to characterize quantum phase transitions in trapped ions. Here we investigate the multiple-quantum-coherence dynamics of a spin-1 Bose–Einstein condensate. By adjusting the quadratic Zeeman shift, the condensate exhibits three quantum phases. Our numerical results show that the spectrum of multiple quantum coherence does indeed catch the quantum critical points. More importantly, with only a few low-order multiple quantum coherences, the spin-1 condensate exhibits rich signals of the many-body dynamics, beyond conventional observables. The experimental implementation of such multiple quantum coherence protocol is also discussed.

Lorraine E. Sadler