Catálogo de publicaciones - revistas

<jats:p>We show that a current-carrying coherent electron conductor can be treated as an effective bosonic energy reservoir involving different types of electron–hole pair excitations. For weak electron–boson coupling, hybrid energy transport between nonequilibrium electrons and bosons can be described by a Landauer-like formula. This allows for unified account of a variety of heat transport problems in hybrid electron–boson systems. As applications, we study the non-reciprocal heat transport between electrons and bosons, thermoelectric current from a cold-spot, and electronic cooling of the bosons. Our unified framework provides an intuitive way of understanding hybrid energy transport between electrons and bosons in their weak coupling limit. It opens the way of nonequilibrium reservoir engineering for efficient energy control between different quasi-particles at the nanoscale.</jats:p>

<jats:p>Quantum quenches in the Dicke model were studied both in the thermodynamic limit and the finite systems. For the integrable situation in the thermodynamic limit, the generalized Gibbs ensemble can effectively describe the energy-level occupations for the quench within the normal phase, but it fails for the quench to the superradiant phase. For the finite systems which are considered non-integrable, the post quench systems were studied by comparing with the thermal ensembles. The canonical ensembles are directly available for the quench within the normal phase. With the increasing of the target coupling strength over the equilibrium phase transition critical point, sudden changes take place for the effective temperature and the distance to the thermal ensembles. The thermalization was also studied by comparing with the results of the microcanonical ensembles.</jats:p>

<jats:p>A fiber cladding surface plasmon resonance (SPR) bending sensor is realized by the cladding of the fiber structure. By employing coating film, the sensing zone is protected and the toughness of the sensor increases. Three different sensing probes are tested, the experiment results indicate that the two parameters (wavelength sensitivity and light intensity sensitivity) sensing performances of the eccentric butt joint structures are superior to that of hetero-core structure, and the SPR bending sensor based on hetero-core structure is stable and uneasy to damage. By employing hetero-core fiber and silver film, a fiber cladding SPR bending sensor with better stabilization and sensing performance is realized. The proposed fabricating method of sensing probe with coating film provides a new approach for fiber SPR-distributed bending sensor.</jats:p>

<jats:p>We perform the first-principles investigations of the structural, elastic, electronic, and optical properties of Sr<jats:italic>B</jats:italic>O<jats:sub>3</jats:sub> (<jats:italic>B</jats:italic> = Cr, Fe) perovskites under pressure based on density functional theory (DFT). This is the first detailed pressure-dependent study of the physical properties for these compounds. The calculated structural parameters are consistent with the existing experimental results and slightly decrease with the application of pressure. The mechanical properties are discussed in detail and reveal that the SrCrO<jats:sub>3</jats:sub> is harder than SrFeO<jats:sub>3</jats:sub>. Without pressure, these compounds behave like half-metals, confirmed by their band structure and density of states. Although the SrCrO<jats:sub>3</jats:sub> retains its half-metallic nature under pressure, SrFeO<jats:sub>3</jats:sub> becomes metallic for both up-spin and down-spin configuration. Both charge density and bond overlap population reveal the covalent nature of Cr–O bond and Fe–O bond in the studied compounds. The optical properties of Sr<jats:italic>B</jats:italic>O<jats:sub>3</jats:sub>, also discussed for the first time, reveal some interesting results.</jats:p>

<jats:p>Photoelectron momentum distribution of hydrogen molecular ion in a circularly polarized laser pulse is calculated by solving the three-dimensional time-dependent Schrödinger equation (3D-TDSE). At the intermediate internuclear distance, an unusual multi-peak structure is observed in the angular distribution, which is proved to be a signature of the transient localization of the electron upon alternating nucleus. By tracing the time-dependent ionization rate and bound state populations, we provide a clear evidence that the transient electron localization still exists in circularly polarized pulse and the corresponding multiple ionization bursts are directly mapped onto observable angular distributions. In addition, we introduce an intuitive strong-field approximation model which incorporates laser-induced subcycle internal electron dynamics to isolate the effect of the Coulomb potential of the parent ions. In this way, the timing of each ionization burst can be directly read out from the angular distributions. Our results suggest that the ionization time serves as a sensitive tool encoding intramolecular electron dynamics and can be measured using attoclock technique.</jats:p>

<jats:p>We investigate interference properties of a trapped atom interferometer where two symmetric optical dipole traps (ODTs) act as the atomic wave-packets splitter and combiner with internal state labelling. After the preparation of initial superposition states, the atomic wave-packet is adiabatically split and moves into two spatially separate asymmetric ODTs. The atomic wave-packets in two ODTs are then adiabatically recombined after a duration of free evolving in traps, completing the interference cycle of this atom interferometer. We show that the interferogram exhibits a series of periodic revivals in interference visibility. Furthermore, the revival period decreases as the asymmetry of two dipole potentials increases. By introducing an echo sequence to the interferometer, we show that while the echo effect is not influenced by the asymmetry of the two ODTs, the onset of periodic revivals changes by the echo sequence. Our study provides an effective method to cancel or compensate the phase shift caused by position and time correlated force.</jats:p>

<jats:p>Fresnel incoherent correlation holography (FINCH) has the ability to generate three-dimensional images with a super-resolution by using incoherent sources. However, there are unwanted direct current term and twin image in interferograms, so it is of great significance to find a method to eliminate them. Phase-shifting technology is a most widely used technique for this task, but its three-step phase-shifting is not suitable for the instantaneous measurement of dynamic objects, and the quality of reconstructed image with the traditional two-step phase-shifting is lower. In this paper, we present a method of enhancing the resolution through using a two-step phase-shifting technology based on the discrete wavelet transform. After two-step phase-shifting, the resulting hologram is a superposition of multiple forms. The frequency of the resulting hologram is decomposed into different levels through using discrete wavelet transform, then the image is reconstructed after retrieving the low frequency band. Various experiments have verified the effectiveness of this method.</jats:p>

<jats:p>We show that chaotic state can be produced as an output of vacuum state evolving in diffusion channel, while displaced chaotic state is output of a coherent state evolving in diffusion channel. We also introduce the thermo vaccum state for the displaced chaotic state and evaluate the average photon number. The displaced chaotic state may be used exhibiting quantum controlling.</jats:p>

<jats:p>Quantum speed limit time and entanglement in a system composed of coupled quantum dots are investigated. The excess electron spin in each quantum dot constitutes the physical system (qubit). Also the spin interaction is modeled through the Heisenberg model and the spins are imposed by an external magnetic field. Taking into account the spin relaxation as a non-Markovian process, the quantum speed limit and entanglement evolution are discussed. Our findings reveal that increasing the magnetic field leads to the faster quantum evolution. In addition, the temperature increment causes the longer quantum speed limit time as well as the entanglement degradation.</jats:p>

<jats:p>We develop a new scheme of two-dimensional (2D) and three-dimensional (3D) atom localization via absorption and gain spectra of surface plasmon polaritons (SPPs) in a closed loop four-level atomic system. For the atom–field interaction, we construct a spatially dependent field by superimposing two (three) standing-wave fields (SWFs) in 2D (3D) atom localization, respectively. We achieve high-precision and high spatial resolution of an atom localization by appropriately adjusting the system parameters such as probe field detuning and phase shifts of the SWFs. The absorption and gain spectra are used to attain information about the position of an atom in SPPs. Our proposed scheme opens up a fascinating way to improve the atom localization that supplies some practical applications in a high-dimensional SPPs.</jats:p>