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The \(p\)-wave superfluid phases of 3He-B and 3He-A are topologically nontrivial. Topological properties manifest themselves as the formation of bound states at a surface. Unusual properties of the \(p\)-wave superfluids also appear around impurities, such as an ion immersed in liquid 3He. In this article, we present the mobility of positive and negative ions trapped below a free surface of 3He-B and 3He-A measured down to 250 μK, which is much lower than the temperatures attained in previous experiments in the bulk. Mobility measurements are conducted for two purposes: one is to figure out details of the scattering of a quasiparticle by an impurity in \(p\)-wave superfluids, and the other is to detect the surface Andreev bound states (SABSs) at a free surface of 3He-B formed as a result of the nontrivial topology of 3He-B. We find, in both superfluid phases, that the mobility shows a considerable increase with decreasing temperature. In both superfluid phases, the mobility of a negative ion at high tempe...

Under applied magnetic field, the originally single superfluid 3 He transition near 3 mK in zero field splits into two transitions between which a new A 1 phase emerges. The two second order transitions are marked by abrupt changes in viscosity, zero sound attenuation and nuclear magnetic resonance. To date, the maximum magnetic field for producing A 1 phase is 15 T. The A 1 phase has been identified with a spin-polarized (ferromagnetic) superfluid system which breaks the relative symmetry between spin, orbit and gauge spaces. A superfluid mass current in A 1 is simultaneously a spin current resulting in the propagation of spin-entropy wave. Experiments with spin-entropy wave provide measurements of anisotropic superfluid density and strong coupling parameters, spin diffusion coefficient and texture transformations. Owing to the spin-polarized nature, superflows may be generated by applied magnetic field gradients and measured from the induced magnetic fountain pressure. The mechanical spin density detect...

4 He confined in nanoporous media is an excellent model boson system in a confinement potential. We have studied the superfluid and thermodynamic properties of 4 He confined in a porous glass that has nanopores of 2.5 nm diameter. It is shown that the confinement of 4 He in nanopores produces a new quantum state, the localized Bose–Einstein condensation (LBEC) state, and markedly alters the pressure–temperature ( P – T ) phase diagram. In the LBEC state the global phase coherence is destroyed by strong atomic correlation or by the random potential of a substrate. The formation of LBEC leads to an anomalous reduction of the superfluid transition temperature T c , determined by the torsional oscillator technique, and the behavior of a quantum phase transition near 0 K. The contributions of roton and phonon excitations to the heat capacity provide definitive evidence of the LBEC state.

A quasiparticle scattering model developed by Monarkha and Kono is explored further to include magnetic field effects on superfluid 3 He. It successfully explains the absence of magnetic field effects in superfluid 3 He-A and normal 3 He. Both an explicit magnetic-field-dependent term in the Bogoliubov quasiparticle energy and the distortion of energy gap are the origin of anisotropic properties of superfluid 3 He-B in magnetic field. In order to quantitatively compare the model with experimental observation, the energy gap distortion has been numerically evaluated by taking into account Landau's Fermi liquid effect up to F 0 a . The Leggett rotation is considered in an ad hoc fashion in 3 He-B. The experimental data can be satisfactorily interpreted by assuming that the rotation considered to be realized only in the vicinity of the free surface extends to the bulk. The numerical value of the Landau parameter is important in obtaining quantitative agreement. This might provide a new experimental possibili...

The study of the behaviors of the roton excitation in a Bose system is performed on the basis of Bogoliubov's procedure. The method of the present theory is a generalization of Bohm-Pines' theory of electron gases to a quantum field theory. Rotons in our model are connected with the quasi-particles described by the translational motion in the condensate wavefunction, thus they are viewed just like as solitons in a nonlinear field theory. We will show that the roton-momentum P 0 is intimately linked to the vortical motion in the system. The rest energy of roton is also obtained.

Nonlinear time evolution of the condensate wave function in superfluid films is studied on the basis of a Schrodinger equation, which incorporates van der Waals potential due to substrate in its fully nonlinear form, and a surface tension term. In the weak nonlinearity limit, our equation reduces to the ordinary (cubic) nonlinear Schrodinger equation for which exact soliton solutions are known. It is demonstrated by numerical analysis that even under strong nonlinearity , where our equation is far different from cubic Schrodinger equation, there exist quite stable composite “quasi-solitons" . These quasi-solitons are bound states of localized excitations of amplitude and phase of the condensate (superfluid thickness and superfluid velocity, in more physical terms). Thus the present work shows the persistence of the solitonic behavior of superfluid films in the fully nonlinear situation.

A new formulation is given of the critical fluctuation of the superfluid order-parameter. It concerns attempts to derive from fundamental principles the equation of motion of the superfluid order-parameter. It is shown that critical fluctuations of the superfluid order-parameter can be described in terms of quasiparticle fields. The present considerations, predominantly formal, are shown to give a reasonable justification to Pitaevskii's method of procedure and to provide a good quantitative picture of the critical dynamics of superfluid.

Raman linewidths of rotons are calculated in solid parahydrogen with low concentration of orthohydrogen molecules. The electric quadrupole-quadrupole interaction between molecules is considered in the scattering of a roton by an orthohydrogen impuruty, where the phonon contribution to linewidths is neglected. Our results are in good agreement with the recent experiment.

Infrared absorption spectra of S v (0), Q v (0)+ S 0 (0) and S v (0)+ S 0 (0) ( v =1, 2,…) in solid parahydrogen are calculated on the basis of the induction mechanism of dipole moment. Effects of the propagation of rotational excitation on the spectral shape through the electric quadrupole-quadrupole interaction are studied in detail, in agreement with the recent experiments. The difference of the excitation energy in the solid phase from that in a free molecule, which increases systematically for higher overtones, is discussed. The dispersion and overlap interactions can be shown to cause such difference.

A theoretical study is presented of the spherically symmetric phase (SP) of solid orthodeuterium at high pressure, where the processes making one roton split into two and three ones are taken into account. The Raman spectra due to rotational excitations are calculated, where the width of three peaks in the spectra becomes broad with increasing pressure in good agreement with the experiment by Silvera and Wijngaarden. The transition from the SP to the phase of broken symmetry is studied by taking account of the correlation energy. A rapid shift of the frequency of vibron (intramolecular-vibrational excitation) is predicted to occur in the close vicinity of transition pressure.

The ground state of a Quantum Lattice Model (QLM) in which all atoms are quantum-mechanically migrating from site to site on the lattice points is given in the crudest approximation. From the QLM the energy spectrum of roton-like excitation is derived on the basis of a simple picture, where the roton excitation is regarded as the motion of an atom which does not undergo the quantum migration. According to Matsuda and Matsubara, by setting two parameters, the effective mass of QLM m =(1/7) m 0 ( m 0 is the mass of 4 He atom), and the lattice spacing d =3.1 A, the density dependence of Δ and m * in roton spectrum are calculated. The obtained results are somewhat higher than the experiments. However the tendencies of density dependence of these parameters are in an excellent agreement with the experiments.

Phonons and rotons in liquid helium II eject 4 He atoms in evaporation through a single-quantum process. We investigate this phenomenon based on the concept of the “dressed-boson” introduced in the previous work. It is explained why one phonon (or roton) can eject only one helium atom. We discuss the reverse process and find that a beam of helium atoms branches to three refracting beams at a liquid-gas boundary. The values of the transmission rates to the three beams are calculated. Next, we investigate reflection of a phonon (or roton) at a boundary between liquid helium II and solid. In the phenomena, a beam composed of phonons (or rotons) is also expected to branch into three beams after reflection.

A modified “ phonon-roton ” model for liquid Helium II is proposed and is shown to be connected smoothly with the theory of Bose condensation. The method used is the direct extension of the method of “ auxiliary variables “ used by Bogolyubov and Zubarev, and is equivalent to that used by Bohm and Pines in the theory of the electron gas in metals. The phonon excitation is described in terms of the density operator, and the roton part by the so-called individual coordinates. The elimination of the kinematical interaction leads to the following model: The excitations for long wave length are described by phonons, and for short wave length by rotons, and the total number of excitations cannot exceed the total number of the particles. The thermal properties of this model is seen to agree with the experimental fact qualitatively.

Electrical properties of electron bubble produced by a hot tungsten filament immersed in the liquid helium bath were investigated. The electrical current between the filament and the surrounding plate could well be explained by an ohmic flow of the bubble under a strong space charge field. The mobility of the electron bubble was strongly field dependent and the roton creation process was newly introduced for the bubble motion in addition to the well known processes of the phonon and roton scatterings and the interaction between vortex and ion.