Non-universal Fermi polaron in quasi two-dimensional quantum gases |
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| Affiliation: | 1.Department of Physics, Renmin University of China, Beijing 100872, China;2.Beijing Academy of Quantum Information Sciences, Beijing 100193, China;3.Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Renmin University of China, Beijing 100872, China |
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| Abstract: | We consider an impurity problem in a quasi-two-dimensional Fermi gas, where a spin-down impurity is immersed in a Fermi sea of N spin-up atoms. Using a variational approach and an effective two-channel model, we obtain the energy for a wide range of interaction strength and for various different mass ratios between the impurity and the background fermion in the context of heteronuclear mixture. We demonstrate that in a quasi-two-dimensional Fermi gas there exists a transition of the ground state from polaron in the weakly interacting region to molecule in the strongly interacting region. The critical interaction strength of the polaron-molecule transition is non-universal and depends on the particle density of the background Fermi sea. We also investigate the excited repulsive polaron state, and find similar non-universal behavior. |
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| Keywords: | Fermi gas polaron problem two-channel model |
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