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We study the coherent and dissipative aspects of a driven spin-1 Bose-Einstein condensate (BEC) when the Zeeman energy is modulated around a static bias value. Resonances appear when the bias energy matches an integer number of modulation quanta. They constitute the atomic counterpart of Shapiro resonances observed in microwave-driven superconducting Josephson junctions. The population dynamics near each resonance corresponds to slow and non-linear secular oscillations on top of a rapid `micromotion. At long times and in a narrow window of modulation frequencies around each resonance, we observe a relaxation to asymptotic states that are unstable without drive. These stationary states correspond to phase-locked solutions of the Josephson equations generalized to include dissipation, and are analogous to the stationary states of driven superconducting junctions. We find that dissipation is essential to understand this long-time behavior, and we propose a phenomenological model to explain quantitatively the experimental results. Finally, we demonstrate hysteresis in the asymptotic state of the driven spinor BEC when sweeping the modulation frequency across a Shapiro resonance.
We study spin mixing dynamics in a chromium dipolar Bose-Einstein Condensate, after tilting the atomic spins by an angle $theta$ with respect to the magnetic field. Spin mixing is triggered by dipolar coupling, but, once dynamics has started, it is m
Understanding the ground state of many-body fluids is a central question of statistical physics. Usually for weakly interacting Bose gases, most particles occupy the same state, corresponding to a Bose--Einstein condensate. However, another scenario
We measure the mass, gap, and magnetic moment of a magnon in the ferromagnetic $F=1$ spinor Bose-Einstein condensate of $^{87}$Rb. We find an unusually heavy magnon mass of $1.038(2)_mathrm{stat}(8)_mathrm{sys}$ times the atomic mass, as determined b
Atom interferometry with high visibility is of high demand for precision measurements. Here, a parallel multicomponent interferometer is achieved by preparing a spin-$2$ Bose-Einstein condensate of $^{87}$Rb atoms confined in a hybrid magneto-optical
We propose a pump scheme for quantum circulations, including counter-circulations for superposition states, of a spinor Bose-Einstein condensate. Our scheme is efficient and can be implemented within current experimental technologies and setups. It r