相关论文: On Critical Velocities in Exciton Superfluidity
We revisit the exciton mechanism of superconductivity in the framework of microcavity physics, replacing virtual excitons as a binding agent of Cooper pairs by excitations of an exciton-polariton Bose-Einstein condensate. We consider a…
We investigate a phenomenon of creation of excitations in the homogenous Bose-Einstein condensate due to an impurity moving with a constant velocity. A simple model is considered to take into account dynamical effects due to motions of the…
Bilayer electron-hole systems undergo excitonic condensation when the distance d between the layers is smaller than the typical distance between particles within a layer. All excitons in this condensate have a fixed dipole moment which…
An exciton is an electron-hole pair bound by attractive Coulomb interaction. Short-lived excitons have been detected by a variety of experimental probes in numerous contexts. An excitonic insulator, a collective state of such excitons, has…
Excitons are key quasiparticles determining the optical properties of solids. As such, they can be utilized to coherently control the electronic structure of materials using optical femtosecond pulses. Identifying the decoherence mechanism…
The problem of critical velocities in superfluids, that is the comprehension of superfluidity breakdown by flow, has been long standing. One difficulty stems from the existence of several breakdown mechanisms. A major advance has come from…
We discuss the excitons in flat band systems. Quantum metric plays a central role in determining the properties of single exciton excitation as well as the exciton condensate. While the electrons and holes are extremely heavy in flat bands,…
Superfluidity is a well-characterized quantum phenomenon which entails frictionless-motion of mesoscopic particles through a superfluid, such as $^4$He or dilute atomic-gases at very low temperatures. As shown by Landau, the incompatibility…
We will discuss the relevant conditions to observe a critical tunneling current [New J. Phys. 10, 045018 (2008)] in electron double-layer systems at a total filling factor of 1 and find they are related to the effective layer separation and…
Condensation of exciton-polaritons has been recently observed in one-dimensional photonic crystal waveguides, exploiting the interplay of long-lived gap confined eigenmodes and negative mass polariton branches. Here we focus on the…
Bose-Einstein condensation of rotons in helium was considered long ago. It was shown that the relative velocity of the normal motion in this state must be equal to the Landau critical velocity. We argue that the condensation can be attained…
I calculate the superfluid density of a non-equilibrium steady state condensate of particles with finite lifetime. Despite the absence of a simple Landau critical velocity, a superfluid response survives, but dissipation reduces the…
Exciton-polaritons constitute a unique realization of a quantum fluid interacting with its environment. Using Selenide based microcavities, we exploit this feature to warm up a polariton condensate in a controlled way and monitor its…
We find that pancake dipolar condensates can exhibit a roton-maxon character of the excitation spectrum, so far only observed in superfluid helium. We also obtain a condition for the dynamical stability of these condensates. The spectrum…
Consider at a finite temperature $T$ a superfluid moving with a velocity $v$ relative to the thermal bath or its normal component. From Landau's argument there exists a critical $v_c (T)$ beyond which excitations can be spontaneously…
We investigate the possibility of creating X-waves, or localized wave packets, in resonantly excited exciton-polariton superfluids. We demonstrate the existence of X-wave traveling solutions in the coupled exciton-photon system past the…
A theory of critical fluctuations in extreme type-II superconductors subjected to a finite but weak external magnetic field is presented. It is shown that the standard Ginzburg-Landau representation of this problem can be recast, with help…
We present the results of a variational calculation of the frequencies of the low-lying Landau two-fluid hydrodynamic modes in a trapped Fermi superfluid gas at unitarity. Landau's two-fluid hydrodynamics is expected to be the correct…
We give a class of explicit solutions for the stationary and cylindrically symmetric vortex configurations for a ``cool'' two-component superfluid (i.e. superfluid with an ideal gas of phonons). Each solution is characterized only by a set…
We predict a strong enhancement of the critical temperature in a conventional Bardeen-Cooper-Schrieffer (BCS) superconductor in the presence of a bosonic condensate of exciton-polaritons. The effect depends strongly on the ratio of the…