Condensation state of ultra-cold Bose atomic gases with pure gradient interactions with negative coefficient |
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Authors: | Z Cheng |
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Institution: | 1.School of Physics,Huazhong University of Science and Technology,Wuhan,P.R. China |
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Abstract: | Within the framework of quantum field theory, we find that uniform Bose atomic gases
with pure gradient interactions with negative coefficient can undergo a
Bardeen-Cooper-Schrieffer (BCS) condensation below a critical temperature. In the BCS
condensation state, bare atoms with opposite wave vectors are bound into pairs, and
unpaired bare atoms are transformed into a new kind of quasi-particle, i.e. the dressed
atom. The atom-pair system is a condensate or a superfluid and the dressed-atom system is
a normal fluid. At absolute zero temperature the condensate possesses a lowest negative
energy. When the total interaction strength of atoms is large enough, the energy of the
condensate is a monotonically increasing function of temperature and interaction strength.
The critical temperature and the effective mass of dressed atoms are derived analytically.
The transition from the BCS condensation state to the normal state is a first-order phase
transition. |
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Keywords: | |
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