Quantum Nucleation of Bubbles in Liquid Heliums

概要

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As the temperature of liquid under negative pressure approaches the absolute zero, nucleation due to thermal fluctuations rarely occurs. Instead of thermal motion, quantum fluctuations may induce the formation of nuclei for transition into a new phase from the metastable state. In this study, a theoretical investigation with molecular cluster model was performed on liquid helium under negative pressure to examine the thermal as well as the quantum nucleation of bubbles and the cross-over temperature from the thermal to the quantum regime. The energy barrier against nucleation was estimated from the molecular interaction due to London's dispersion force. The phase transition from liquid to vapor was shown to be only possible due to the quantum tunneling below 0.25 K for helium-4 and 0.175 K for helium-3. The cross-over temperatures which depends on the square root of the single particle quantum vibrational energy times the free energy of the critical cluster were comparable to the calculated results obtained through the density functional approach and the functional-integral approach. Also, the negative pressures needed for bubble nucleation on vortices lines were calculated and the results were found to be in good agreement with observations.
社団法人日本物理学会の論文
2002-09-15