报告题目: |
Clock Shifts of Optical Transitions in Ultracold Atomic Gases |
报告人: |
Zhenhua Yu 博士 |
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Niels Bohr Institute，University of Copenhagen
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报告时间: |
2010-09-16 10:30 |
报告地点: |
科学馆213报告厅 |
主办单位: |
高等研究院 |
简介: |
The state of the art of the standard for time is given by atomic
clocks. The new generation of atomic clocks make use of the optical
transitions of identical fermionic atoms loaded in optical lattices.
In such systems, the resonant frequency shifts due to the interatomic
interactions and the recoiling of atoms are expected to be strongly
suppressed. However, in recent experiments of Campbell et al. [Science
324, 360 (2009)], when the fractional precision reaches the level of 1
× 10−16, frequency shifts given rise by the interactions are
observed. To study the time evolution of the atomic clocks, we
introduce a pseudospin formalism describing the density matrix of
atoms. We derive a Bloch equation for the pseudospins which
incorporates both spatial dependence of the probe laser field and
interatomic interactions. We show that the interaction effects on the
frequency shift are introduced in by the spatial inhomogeneity of the
probe laser during the process of probe. In the low temperature
semiclassical regime, we find that the magnitude of the shift is
proportional to the temperature. |
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