Recent Progress in Study of Superfluid in doped quantum solution

【作者】 李辉；

【Author】 Hui Li;Institute of Theoretical Chemistry,Laboratory of Theoretical and Computational Chemistry;

【机构】 Institute of Theoretical Chemistry,Laboratory of Theoretical and Computational Chemistry,Jilin University；

【摘要】 Superfluidity is a remarkable manifestation of quantum mechanics at the macroscopic scale. When cooled to very low temperature, liquid helium exhibits the very peculiar property of flowing without friction or dissipation. This phenomenon has been observed and well characterized in the bulk liquid helium phase. In clusters and nanodroplets, 4 He and pH2 have been shown to exhibit superfluid effects but a direct assessment of the superfluid response of mixtures of these two bosons remains an open area of investigation. To understand the properties of microscopic superfluid mixtures, we perform path integral Quantum Monte Carlo simulations of different rotors(HCN, CO2 and OCS) doped pH2 or 4 He clusters. Size-dependent phase separation is observed and the onset thereof is characterized and attributed to a delicate interplay between interaction induced localization and the filling of solvation shells. Our findings shed new light on pioneering experiments performed on OCS with pH2 embedded in helium droplets where the disappearance of the Q-branch spectroscopic feature was attributed to the onset of the superfluidity of pH2. Our results rather suggest that the helium environment significantly suppresses the superfluid response of pH2 and that the disappearance of the Q-branch may very well instead be a sign of phase separation of the two bosonic species.更多还原

【Abstract】 Superfluidity is a remarkable manifestation of quantum mechanics at the macroscopic scale. When cooled to very low temperature, liquid helium exhibits the very peculiar property of flowing without friction or dissipation. This phenomenon has been observed and well characterized in the bulk liquid helium phase. In clusters and nanodroplets, 4 He and pH2 have been shown to exhibit superfluid effects but a direct assessment of the superfluid response of mixtures of these two bosons remains an open area of investigation. To understand the properties of microscopic superfluid mixtures, we perform path integral Quantum Monte Carlo simulations of different rotors(HCN, CO2 and OCS) doped pH2 or 4 He clusters. Size-dependent phase separation is observed and the onset thereof is characterized and attributed to a delicate interplay between interaction induced localization and the filling of solvation shells. Our findings shed new light on pioneering experiments performed on OCS with pH2 embedded in helium droplets where the disappearance of the Q-branch spectroscopic feature was attributed to the onset of the superfluidity of pH2. Our results rather suggest that the helium environment significantly suppresses the superfluid response of pH2 and that the disappearance of the Q-branch may very well instead be a sign of phase separation of the two bosonic species.更多还原