We investigate the collective excitations of 3He-4He mixture films at zero temperature within the random phase approximation and linear response theory. In a low concentration regime of 3He, a level repulsion between zero sound and third sound modes is derived, which opens the possibility to observe quantum mechanical coherence between a 3He particle-hole pair and the condensate of 4He. We also investigate the 3He-4He vertex corrections in the ladder approximation, and show that the third branch, the combined mode of fermionic particle-hole pair and the third sound quanta, provides a unique correction to the Landau f function. Some implications for a fermion-boson mixture of alkali atoms in a potential trap are discussed.
|ジャーナル||Physical Review B - Condensed Matter and Materials Physics|
|出版ステータス||Published - 2003 8月|
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