凝聚态物理
The electronic structure of the first Pu based superconductor PuCoGa5 is explored using photoelectron spectroscopy and a novel theoretical scheme. Exceptional agreement between calculation and experiment defines a path forward for…
We report empirical evidences on the existence of a conditional dynamics driving the evolution of financial assets which is found in several markets around the world and for different historical periods. In particular, we have analyzed the…
Scaling analysis reveals striking regularities in earthquake occurrence. The time between any one earthquake and that following it is random, but it is described by the same universal-probability distribution for any spatial region and…
We report measurements of the time for spin flip from dark (non-light emitting) exciton states in quantum dots to bright (light emitting) exciton states in InP quantum dots. Dark excitons are created by two-photon excitation by an ultrafast…
We study theoretically the magnetic resonance force microscopy (MRFM) in oscillating cantilever-driven adiabatic reversals (OSCAR) technique, for the case when the cantilever tip oscillates parallel to the surface of a sample. The main…
Thermal fluctuations lift the high ground state degeneracy of the classical nearest neighbour pyrochlore antiferromagnet, with easy plane anisotropy, giving a first order phase transition to a long range ordered state. We show, from spin…
We investigate, analytically and numerically, the emergence of spatio-temporal order in nonequilibrium scalar field theories. The onset of order is triggered by destabilizing interactions (DIs), which instantaneously change the interacting…
Two kinds of topological excitations, skyrmions and monopoles, are studied. It is revealed that these two types of excitations originate from different order parameter fields that reflect different spatial distributions of the Neel vector.…
We investigate the dynamics of the spin-boson model when the spectral density of the boson bath shows a resonance at a characteristic frequency $\Omega$ but behaves Ohmically at small frequencies. The time evolution of an initial state is…
A generalised method of using feedback to control Bose-Einstein condensates is introduced. The condensates are modelled by the Gross-Pitaevskii equation, so only semiclassical fluctations can be suppressed, and back-action from the…
We use subpicosecond laser pulses to generate and monitor in real time collective oscillations of electrons in a modulation-doped GaAs quantum well. The observed frequencies match those of intersubband spin- and charge-density excitations.…
The effect of an external bias voltage and fluctuating electromagnetic fields on both the fundamental frequency and damping of cantilever vibrations is considered. An external voltage induces surface charges causing cantilever-sample…
The spin-1 ferromagnetic Blume-Capel film with an alternating crystal field $\Delta=\Delta_1$ on the odd layers and $\Delta=\Delta_2$ on the even ones is considered in the mean field approximation. The ground state phase diagrams in the…
We use linked-cluster series expansions, both at T=0 and high temperature, to analyse the phase structure of the spin-$\half$ Heisenberg antiferromagnet with competing first and second-neighbor interactions on the 3-dimensional…
We analyze the generation and mobility of discrete solitons in Bose-Einstein condensates confined in an optical lattice under realistic experimental conditions. We discuss first the creation of 1D discrete solitons, for both attractive and…
It is shown that pinning of an electron Wigner crystal by a small concentration of charged impurities creates the finite density of charged localized states near the Fermi level. In the case of residual impurities in the spacer this density…
We investigate how the transition from integrability to nonintegrability occurs by changing the parameters of the Hamiltonian of a Heisenberg spin-1/2 chain with defects. Randomly distributed defects may lead to quantum chaos. A similar…
We describe the construction and operation of an external cavity diode laser in which the diode is cooled to -45 C. This technique allows us to pull the wavelength of a nominally 782 nm diode to operate at 766.7 nm, a change of over 15 nm.…
The Wigner delay time is addressed semiclassically using the Miller's S-matrix expressed in terms of open orbits. This leads to a very appealing expression, in terms of classical paths, for the energy averaged Wigner time delay in chaotic…
We argue that turbulence in superfluids is governed by two dimensionless parameters. One of them is the intrinsic parameter q which characterizes the friction forces acting on a vortex moving with respect to the heat bath, with 1/q playing…