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The 361st forum: Phase transition in a spin-orbital-angular-momentum coupled Bose-Einstein condensate

Date: 2019-04-26
Time: 10:00
Venue: M253
Speaker: 江开军 研究员





Coupling between particle's spin and orbital motion is ubiquitous in atoms, photons, solid materials and many other systems. It contributes to the topological properties like quantum-Hall effect in solid materials and electronic fine structure in atoms. Ultracold atoms with a high tunability provides an ideal platform to study spin-orbit (SO) coupling. Spin-linear-momentum (SLM) coupling has been observed in quantum gases and subsequently a variety of exotic quantum states have been explored. While the experimental study on the other kind of SO coupling, namely the spin-orbital-angular-momentum (SOAM) coupling, is still lacking.

In this talk, I will report the experimental observation of the ground-state phase diagram of the SOAM coupled Bose-Einstein condensate. By inducing a Raman transition using a pair of Gaussian and Laguerre-Gaussian (LG) laser beams, we realize SOAM coupling of ultracold atoms. We observe phase transitions when the two-photon Raman coupling strength or detuning approaches the critical value. The phase transitions are classified as the first order, which feature a discontinuous jump of the angular momentum (OAM) and the spin polarization. We demonstrate the hysteresis loop across the first-order phase transition. The role of interatomic interaction on the phase transition is also elucidated.

邀 请 人:刘伍明(电话:8264 9249)

联 系 人:李园园(电话:8264 9364)