Recently the influence of antisymmetric spin-orbit coupling has been studied in novel topological superconductors such as half-Heuslers and artificial hetero-structures. We investigate the effect of Rashba and/or Dresselhaus spin-orbit couplings on the band structure and topological properties of a two-dimensional noncentrosymetric superconductor. For this goal, the topological helical edge modes are analyzed for different spin-orbit couplings as well as for several superconducting pairing symmetries. To explore the transport properties, we examine the response of the spin-polarized edge states to an exchange field in a superconductor-ferromagnet heterostructure. The broken chiral symmetry causes the uni-directional currents at opposite edges.

We propose a technique that enables the creation of quantum discord between two distant nodes, each containing a cavity consist of the Bose-Einstein condensate, by applying a non-ideal Bell-like detection on the output modes of optical cavities. We find the covariance matrix of the system after the non-ideal Bell-like detection, showing explicitly that one enables manipulation of the quantum correlations, and particularly quantum discord, between remote Bose-Einstein condensates. We also find that the non-ideal Bell-like detection can create entanglement between distant Bose-Einstein condensates at the two remote sites.

The superconducting reservoir effect on the current carrying transport of a double quantum dot in Markovian regime is investigated. For this purpose, a quantum master equation (QME) at finite temperature is derived for the many-body density matrix of an open quantum system. The dynamics and the steady-state properties of the double quantum dot system for arbitrary bias are studied. We will show that how the populations and coherencies of the system states are affected by superconducting leads. The energy parameter of system contains essentially four contributions due to dots system-electrodes coupling, intra dot coupling, two quantum dots inter coupling and superconducting gap. The coupling effect of each energy contribution is applied to currents and coherencies results. In addition, the effect of energy gap is studied by considering the amplitude and lifetime of coherencies to get more current through the system. IntroductionRecent years, it has received remarkable progress in experimental techniques to study the electron transport through nanoscopic systems where semiconductor quantum dots (QDs) are connected to superconducting electrodes [1][2][3][4][5].When the coupling in superconductor is sufficient, the Cooper pairs in low temperatures develop global coherency, which suppress the global macroscopic superconductivity. These studies are desirable for very sensitive and controllable coherent switching devices which make it possible to investigate quantum computing and different quantum effects of fundamental physics, such as single electron tunneling, quantum phase transition, and macroscopic condensation [6][7][8][9]. Keldysh nonequilibrium Green's functions (NEGF) [10,11], scattering theory(ST) [12,13] and quantum master equation (QME) [14][15][16][17]approaches can be used to study the nonequilibrium electron transport through a quantum system (QD or single molecule). ST is limited to elastic processes while the NEGF can treat in elastic and inelastic ones. Both approaches are applied to the tunneling coupling exactly, but usually the correlations inside the dot are fully neglected or the mean field and perturbation theory is used. QME is an alternative tool for studying the irreversible dynamics of quantum systems coupled to a macroscopic environment. This approach treats the correlations inside the dot very accurately (even exactly in the case of model systems) but the tunneling is usually considered in the Born-Markov approximation. Markovian quantum master equation [18,19] provides an intuitive understanding the non-equilibrium transport problem of the system dynamics [20]and has been used in various fields such as quantum optics [21,22], solid state physics [23],and chemical dynamics [24].For example, electrons tunneling through molecules, coupled QDs [25] and superconducting systems have been studied by this approach. Recently, QME approach has been applied to investigate electron tunneling through molecules or coupled QDs [26,27] such as, studying the rectification properties of a system of coupled...

The depletion of a quasi-two-dimensional (quasi-2D) dipolar Bose condensed gas in the presence of both contact and long-range 1/r interactions is investigated in the framework of Hartree–Fock–Bogoliubov (HFB) approximation. When the characteristic wavelength of a mode is much larger than the trap size, the dipole-dipole (DD) interaction can be treated as a contact interaction and in the low momentum limit the long-range nature of the 1/r interaction has the dominant contribution and leads to the nonlinear (nonphononic) dispersion relation. We will show that quantum depletion is temperature independent and is determined by the contact, DD and longrange 1/r coupling constants (ɛdd = gd/g and C). The the quantum depletion is affected by long-range 1/r interaction and at large momentum limits the momentum dependence of quantum depletion unaffected by 1/r interaction.

The twist angle dependence of the Josephson critical current of d-wave superconductors in one junction and a granular system is considered. Our results show that the twist angle dependence of the d-wave Josephson critical current is the same for one junction and a granular system. The magnetic field dependences of the critical-current of a granular d-wave superconductor has also been determined by considering the rectangular and circular junction model of an array of small superconducting particles which interacting by Josephson coupling through insulating barriers. We will show that in the case of circular model, the critical current of the Josephson current is larger than that of rectangular one.