相关论文: Transmission and reflection of phonons and rotons …
We solve the problem of beams of phonons and rotons incident on, and interacting with, solid surfaces. Phonons and rotons are the quasiparticles of superfluid helium and have a unique dispersion curve. The dispersion curve controls the…
We find the pressure, due to the thermal excitations of superfluid helium, at the interface with a solid. The separate contributions of phonons, $R^-$ rotons and $R^+$ rotons are derived. The pressure due to $R^-$ rotons is shown to be…
I develop here the microscopic quantum theory for description of creation of phonons and rotons in superfluid helium by a solid heater. Starting with correct transfer Hamiltonian describing a coupling between the solid and liquid $^4$He the…
A new method of obtaining the interaction Hamiltonian of phonons at superfluid helium-solid interface is proposed in the work. Equations of hydrodynamic variables are obtained in terms of second quantization if helium occupies a half-space.…
The probability of evaporation induced by $R^+$ and $R^-$ rotons at the surface of superfluid helium is calculated using time dependent density functional theory. We consider excitation energies and incident angles such that phonons do not…
Based on interrelation between the thermodynamic and electromechanical phenomena in superfluid helium, the explanation of experimentally found features of microwave interaction in the frequency range of 40-200 GHz is given. Due to fast…
Superfluid helium II contains excitations known as rotons. Their properties have been studied experimentally for more than 70 years but their structure is not fully understood. Feynman's 1954 description, involving rotating flow patterns,…
We introduce an effective point-particle action for generic particles living in a zero-temperature superfluid. This action describes the motion of the particles in the medium at equilibrium as well as their couplings to sound waves and…
Liquid helium and spin-1/2 cold-atom Fermi gases both exhibit in their superfluid phase two distinct types of excitations, gapless phonons and gapped rotons or fermionic pair-breaking excitations. In the long wavelength limit, revising and…
The purpose of the paper is to suggest a new method which allows one to study multiple coherent reflection/transmissions by partially transparent interfaces (e.g. in multi-layer mesoscopic structures or grain boundaries in high-Tc's) in the…
The dynamics of strongly interacting quantum fluids such as Helium II are fundamentally distinct from those of dilute, contact-interacting atomic Bose-Einstein condensates. Most dramatically, superfluids with finite-range interactions can…
Interfaces play an essential role in phonon-mediated heat conduction in solids, impacting applications ranging from thermoelectric waste heat recovery to heat dissipation in electronics. From a microscopic perspective, interfacial phonon…
Roton dispersion relations, displaying a pronounced "roton" minimum at finite momentum, were firstly predicted by Landau and have been extensively explored in correlated quantum systems at low temperatures. Recently, the roton-like…
The longitudinal friction acting on a vortex line in superfluid $^4$He is investigated within a simple model based on the analogy between such vortex dynamics and that of the quantal Brownian motion of a charged point particle in a uniform…
The propagation of the excess of quasiparticles and phonons produced by a nuclear recoil inside Sn and Zn superheated superconducting granules will be discussed. The decay towards equilibrium of the initial disturbance is assumed to be a…
We propose a theory which deals with the structure and interactions of volume elements in liquid helium II. The approach consists of two nested models linked via parametric space. The short-wavelength part describes the interior structure…
The new model of phonon transmission across the interface between two crystals is proposed featured by taking into account the mismatch of crystal lattices. It has been found that the mismatch of lattices results in phonon scattering at the…
The broadband and ultrafast photoresponse of graphene has been extensively studied in recent years, although the photoexcited carrier dynamics is still far from being completely understood. Different experimental approaches imply either one…
At a normal-metal/superconductor interface, an incident electron from the normal-metal (N) side can be normally reflected as an electron or Andreev reflected as a hole. We show that pronounced lateral shifts along the interface between the…
Parametric excitation of rotons by oscillating electric field exhibits a narrow resonance at the roton minimum frequency. The resonance width is in good agreement with experimental results on the microwave absorption in superfluid helium.