Roton dipole moment
The roton excitation in the superfluid 4He does not possess a stationary dipole moment. However, a roton has an instantaneous dipole moment, such that at any given moment one can find it in the state either with positive or with negative dipole moment projection on its momentum direction. The instantaneous value of electric dipole moment of roton excitation is evaluated. The result is in reasonable agreement with recent experimental observation of the splitting of microwave resonance absorption line at roton frequency under external electric field.
KeywordsDipole Moment JETP Letter Electric Dipole Moment Helium Atom Momentum Direction
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