Fig. 5
From: Spin current generation and relaxation in a quenched spin-orbit-coupled Bose-Einstein condensate
Observation of deformed atomic clouds and BEC shape oscillations. a–d Observation of deformed atomic clouds at early stages of the SDM. a, b TOF images for ΩF = 0 and ΩF = 2.1 Er at thold = 0.5 ms are shown for comparison. The corresponding integrated optical density (ODy) versus the momentum in the SOC direction \(\left( {\hat y} \right)\) for the spin down and up components is shown respectively in c, d. e, f Observation of BEC shape oscillations. The data showing the aspect ratio Wy/Wz′ (see Methods) of the condensate measured at various thold are extracted from the SDM measurements in Fig. 3, except for the additional measurements #2 and #3 in e. e For the three independent measurements in the bare case, the observed oscillations possess a complicated behavior without having a well-defined frequency given the error bars and the fluctuation in the data. Select TOF images for measurement #1 are shown in Fig. 2a. f In the dressed cases, aspect ratio oscillations with a well-defined frequency are observed in measurements at three different ΩF. The average frequency of the three aspect ratio oscillations obtained from the damped sinusoidal fit is around 58 Hz, consistent with the expected frequency for the m = 0 quadrupole mode \(f_{m = 0} = \sqrt {2.5} \omega _z{\mathrm{/}}(2\pi )\sim 59\,{\mathrm{Hz}}\) for a cigar-shape BEC in the limit of ωz/ωx,y << 152. Note that ωz is not modified by Raman lasers and thus does not depend on ΩF. Select TOF images for ΩF = 1.3 Er are shown in Fig. 2b. The representative error bars in (e, f) are standard deviation of at least three measurements. The dashed lines indicate thold ~ 2τdamp after which the SDM is fully damped out
