Trung tâm Vật lý lý thuyết - Trung tam Vat ly ly thuyet

Seminar Vật lý lý thuyết và Vật lý tính toán:
Tên báo cáo	Beliaev theory of spinor Bose-Einstein condensates
Người trình bày	Nguyễn Thanh Phúc
Cơ quan	Khoa Vật lý, Đại học Tokyo
Ngày	Thứ Ba, 14-08-2012
Giờ	10:00 AM
Địa điểm	Phòng họp tầng 1, Viện Vật lý, 10 Đào Tấn, Ba Đình, Hà Nội
Tóm tắt	By generalizing the Green’s function approach proposed by Beliaev [1, 2], we investigate the effect of quantum depletion on the energy spectra of elementary excitations in an F = 1 spinor Bose-Einstein condensate, in particular, of 87Rb atoms in an external magnetic field. We find that quantum depletion increases the effective mass of magnons in the spin-wave excitations with quadratic dispersion relations. The enhancement factor turns out to be the same for both ferromagnetic and polar phases, and also independent of the magnitude of the external magnetic field. The lifetime of these magnons in a 87Rb spinor BEC is shown to be much longer than that of phonons. We propose an experimental setup to measure the effective mass of these magnons in a spinor Bose gas by exploiting the effect of a nonlinear dispersion relation on the spatial expansion of a wave packet of transverse magnetization. This type of measurement has practical applications, for example, in precision magnetometry. [1] S. T. Beliaev, Soviet Physics JETP 7 (1958) 299. [2] S. T. Beliaev, Soviet Physics JETP 7 (1958) 289.

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