Catálogo de publicaciones - revistas

<jats:p>Capacity of dense coding via correlated noisy channel is greater than that via uncorrelated noisy channel. It is shown that the weak measurement and reversal measurement need to further improve their quantum dense coding capacity in correlated amplitude damping channel, but this improvement is very small in correlated phase damping channel and correlated depolarizing channel.</jats:p>

<jats:p>Reference-frame-independent quantum key distribution (RFI-QKD) can allow a quantum key distribution system to obtain the ideal key rate and transmission distance without reference system calibration, which has attracted much attention. Here, we propose an RFI-QKD protocol based on wavelength division multiplexing (WDM) considering finite-key analysis and crosstalk. The finite-key bound for RFI-QKD with decoy states is derived under the crosstalk of WDM. The resulting secret key rate of RFI-QKD, which is more rigorous, is obtained. Simulation results reveal that the secret key rate of RFI-QKD based on WDM is affected by the multiplexing channel number, as well as crosstalk between adjacent channels.</jats:p>

<jats:p>We study the property of magnetopolaron in a parabolic quantum dot under the Rashba spin–orbit interaction (RSOI) by adopting an unitary transformation of Lee–Low–Pines type and the variational method of Pekar type with and without considering the temperature. The temporal spatial distribution of the probability density and the relationships of the oscillating period with the RSOI constant, confinement constant, electron–phonon coupling strength, phonon wave vector and temperature are discussed. The results show that the probability density of the magnetopolaron in the superposition of the ground and first excited state takes periodic oscillation (<jats:italic>T</jats:italic> <jats:sub>0</jats:sub>/period) in the presence or absence of temperature. Because of the RSOI, the oscillating period is divided into different branches. Also, the results indicate that the oscillating period increases (decreases) when the RSOI constant, electron-phonon coupling strength and phonon wave vector (the confinement constant) increase in a proper temperature, and the temperature plays a significant role in determining the properties of the polaron.</jats:p>

<jats:p>Using coupled Gross–Pitaevksii (GP) equations, we simulate the output of one-dimensional pulsed atom laser in space station. We get two atom laser pulses propagating in opposite directions with one pulsed RF coupling. Compared with atom laser under gravity, the laser pulse in microgravity shows much slower moving speed, which is suitable to be used for long-term investigations. We also simulate the output flux at different coupling strengths.</jats:p>

<jats:p>Motivated by the fact that Weyl fermions can emerge in a three-dimensional topological insulator on breaking either time-reversal or inversion symmetries, we propose that a topological quantum phase transition to a Weyl semimetal phase occurs under the off-resonant circularly polarized light, in a three-dimensional topological insulator, when the intensity of the incident light exceeds a critical value. The circularly polarized light effectively generates a Zeeman exchange field and a renormalized Dirac mass, which are highly controllable. The phase transition can be exactly characterized by the first Chern number. A tunable anomalous Hall conductivity emerges, which is fully determined by the location of the Weyl nodes in momentum space, even in the doping regime. Our predictions are experimentally realizable through pump-probe angle-resolved photoemission spectroscopy and raise a new way for realizing Weyl semimetals and quantum anomalous Hall effects.</jats:p>

<jats:p>In order to understand our previous numerical finding that steady-state entanglement along the instability boundary remains unchanged in a three-mode optomechanical system [<jats:italic>Phys. Rev. A</jats:italic> <jats:bold>101</jats:bold> 023838 (2020)], we investigate in detail the boundary entanglement in a simpler two-mode optomechanical system. Studies show that both the mechanism to generate entanglement and the parameter dependence of boundary entanglement are quite similar in these two models. Therefore, the two-mode system has captured the main features in the three-mode system. With the help of analytical calculations and discussing in a much bigger parameter interval, we find that the unchanging behavior previously discovered is actually an extremely slow changing behavior of the boundary entanglement function, and most importantly, this nearly invariant boundary entanglement is a general phenomenon via parametric down conversion process in the weak dissipation regime. This is by itself interesting as threshold quantum signatures in optomechanical phonon lasers, or may have potential value in related applications based on boundary quantum properties.</jats:p>

<jats:p>By introducing a discrete memristor and periodic sinusoidal functions, a two-dimensional map with coexisting chaos and hyperchaos is constructed. Various coexisting chaotic and hyperchaotic attractors under different Lyapunov exponents are firstly found in this discrete map, along with which other regimes of coexistence such as coexisting chaos, quasi-periodic oscillation, and discrete periodic points are also captured. The hyperchaotic attractors can be flexibly controlled to be unipolar or bipolar by newly embedded constants meanwhile the amplitude can also be controlled in combination with those coexisting attractors. Based on the nonlinear auto-regressive model with exogenous inputs (NARX) for neural network, the dynamics of the memristive map is well predicted, which provides a potential passage in artificial intelligence-based applications.</jats:p>

<jats:p>Autonomous Boolean networks (ABNs) have been successfully applied to the generation of random number due to their complex nonlinear dynamics and convenient on-chip integration. Most of the ABNs used for random number generators show a symmetric topology, despite their oscillations dependent on the inconsistency of time delays along links. To address this issue, we suggest an asymmetrical autonomous Boolean network (aABN) and show numerically that it provides large amplitude oscillations by using equal time delays along links and the same logical gates. Experimental results show that the chaotic features of aABN are comparable to those of symmetric ABNs despite their being made of fewer nodes. Finally, we put forward a random number generator based on aABN and show that it generates the random numbers passing the NIST test suite at 100 Mbits/s. The unpredictability of the random numbers is analyzed by restarting the random number generator repeatedly. The aABN may replace symmetrical ABNs in many applications using fewer nodes and, in turn, reducing power consumption.</jats:p>

<jats:p>Hyperfine structures and the field effects of IBr molecule in its rovibronic ground state are theoretically studied by diagonalizing the effective Hamiltonian matrix. Perturbations of high-<jats:italic>J</jats:italic> levels up to 4 are taken into account when studying the hyperfine sub-levels of the <jats:italic>J</jats:italic> = 0 level, and thus, an 80 × 80 matrix is constructed and solved. Some of the experimentally absent molecular constants are computed using Dalton program. Our results will be helpful in the experimental investigation of manipulation and further cooling of cold IBr molecules.</jats:p>

<jats:p>We report the study on the complete three-body Coulomb explosion (CE) of N<jats:sub>2</jats:sub>O<jats:sup> <jats:italic>q</jats:italic>+</jats:sup> (<jats:italic>q</jats:italic> = 5, 6) induced by 56-keV/u Ne<jats:sup>8+</jats:sup> ion collision with N<jats:sub>2</jats:sub>O gaseous molecule. Six CE channels for N<jats:sub>2</jats:sub>O<jats:sup>5+</jats:sup> and seven for N<jats:sub>2</jats:sub>O<jats:sup>6+</jats:sup> are identified by measuring three ionic fragments and the charge-changed projectile in quadruple coincidence. Correspondingly the kinetic energy release (KER) and momentum correlation angle (MCA) distributions of three ionic fragments for each of the CE channels are also deduced. Numerical computation is presented to reconstruct the geometric structure of N<jats:sub>2</jats:sub>O<jats:sup> <jats:italic>q</jats:italic>+</jats:sup> prior to dissociation based on the measured KER and MCA. The N–N and N–O bond lengths and the N–N–O bond angles of N<jats:sub>2</jats:sub>O<jats:sup> <jats:italic>q</jats:italic>+</jats:sup> for each of the channels are determined.</jats:p>