Other Condensed Matter
System of two-fluid hydrodynamics of superfluid helium with the account of electric field is obtained. These equations are obtained in kinetic approach using quasi-equilibrium distribution function of quasi-particles, which vanishs…
We experimentally investigate the properties of radio-frequency-dressed potentials for Bose-Einstein condensates on atom chips. The three-dimensional potential forms a connected pair of parallel waveguides. We show that rf-dressed…
Electrons on the surface of liquid helium are a widely studied system that may also provide a promising method to implement a quantum computer. One experimental challenge in these studies is to generate electrons on the helium surface in a…
We introduce a random variable approach to investigate the dynamics of a dissipative two-state system. Based on an exact functional integral description, our method reformulates the problem as that of the time evolution of a quantum state…
We investigate the low-energy properties of the Holstein polaron through calculation of the q-dependent phonon spectral function using an improved exact-diagonalization technique, defined over a variational Hilbert space. We perform a…
We study interacting bosons in optical lattices in the weak-tunneling regime in systems that exhibit the coexistence of Mott-insulating and condensed phases. We discuss the nature of the condensed ground state in this regime and the…
We calculate the normalized second-order correlation function for a system of two tunnel-coupled photonic resonators, each one exhibiting a single-photon nonlinearity of the Kerr type. We employ a full quantum formulation: the master…
In the present work a new method for studying porous media by nuclear magnetic resonance of liquid 3He has been proposed. This method has been demonstrated in an example of a clay mineral sample. For the first time the integral porosity of…
We have theoretically investigated a generation of entangled photons from biexcitons in a semiconductor film with thickness in nano-to-bulk crossover regime. In contrast to the cases of quantum dots and bulk materials, we can highly control…
A rigorous derivation of the density functional in the Hohenberg-Kohn theory is presented. With no assumption regarding the magnitude of the electric coupling constant $e^2$ (or correlation), this work provides a firm basis for…
We study Bragg spectroscopy of a strongly interacting Bose-Einstein condensate using time-dependent Hartree-Fock-Bogoliubov theory. We include approximatively the effect of the momentum dependent scattering amplitude which is shown to be…
The frequency-dependent polar dynamics of strained SrTiO3 films grown on DyScO3 are investigated using time-resolved confocal scanning optical microscopy. Microwave frequency electric fields are synchronized with a mode-locked laser and…
The effect of magnetic anisotropy-axis alignment of individual nanoparticles on the collective aging behavior in the superspin glass state of a frozen ferrofluid has been investigated. The ferrofluid studied here consists of maghemite…
Analytical and numerical calculations for a reduced Fermi-Pasta-Ulam chain demonstrate that energy localization does not require more than one conserved quantity. Clear evidence for the existence of a sharp delocalization-localization…
We study the equilibrium properties of dipolar Bose and Fermi gases at finite temperatures. We recently developed a variational ansatz for the phase-space distribution function of a dipolar Fermi gas at finite temperatures. We extend the…
Motivated by recent realizations of microwave-driven nonlinear resonators in superconducting circuits, the impact of environmental degrees of freedom is analyzed as seen from a rotating frame. A system plus reservoir model is applied to…
We propose a scheme to create a metastable state of paired bosonic atoms in an optical lattice. The most salient features of this state are that the wavefunction of each pair is a Bell state and that the pair size spans half the lattice,…
We report a tunable ultrafast fiber laser mode-locked with a graphene saturable absorber. The linear dispersions of the Dirac electrons in graphene enable wideband tunability. We get ~1ps pulses, tunable between 1525 and 1559nm,…
It is shown that the one-dimensional nonlinear Schr\"odinger equation with a dissipative periodic potential, nonlinear losses and linear pump allow for the existence of stable nonlinear Bloch states which are attractors. The model describes…
We provide a theoretical framework to describe the interaction of a propagating guided matter wave with a localized potential in terms of quantum scattering in a confined environment. We analyze how this scattering correlates the…