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Influences of spin-orbit interaction on quantum speed limit and entanglement of spin qubits in coupled quantum dots

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Chinese physics B 2021年第9期30卷 94-100页

作者： M Bagheri Harouni Quantum optics group Department of PhysicsUniversity of IsfahanHezar Jerib St.Isfahan 81764-73441Iran

Quantum speed limit and entanglement of a two-spin Heisenberg XYZ system in an inhomogeneous external magnetic field are *** physical system studied is the excess electron spin in two adjacent quantum *** influences of magnetic field inhomogeneity as well as spin-orbit coupling are ***,the spin interaction with surrounding magnetic environment is investigated as a non-Markovian *** spin-orbit interaction provides two important features:the formation of entanglement when two qubits are initially in a separated state and the degradation and rebirth of the entanglement.

关键词： quantum speed limit time quantum entanglement open quantum systems spin-orbit effects

Electron correlation in fast ion-impact single ionization of helium atoms

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Chinese physics B 2015年第1期24卷 240-246页

作者： E.Ghanbari-Adivi S.Eskandari department of physics and Isfahan Quantum optics group (IQOG) Faculty of Science University of Isfahan Isfahan 81746-73441 Iran

A four-body distorted-wave approximation is applied for theoretical analysis of the fully differential cross sections（FDCS） for proton-impact single ionization of helium atoms in their ground states. The nine-dimensional integrals for the partial amplitudes are analytically reduced to closed-form expressions or some one-dimensional integrals which can be easily calculated numerically. Calculations are performed in the scattering and perpendicular planes. The influence of the target static electron correlations on the process is investigated using a number of different bound-state wave functions for the ground state of the helium targets. An illustrative computation is performed for 75-ke V proton–helium collisions and the obtained results are compared with experimental data and other theoretical predictions. Although for small momentum transfers, the comparison shows a reasonable agreement with experiments in the scattering and perpendicular planes, some significant discrepancies are still present at large momentum transfers in these planes. However, our results are compatible and for some cases, better than those of the other sophisticated calculations.

关键词： single ionization four-body collision distorted-wave approximation electron correlation

Exact Evolution of Ultrashort Hollow-Airy Pulses in the Spatiotemporal Domain

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Chinese physics Letters 2015年第1期32卷 47-51页

作者：张敬芳王兆英林强 Institute of optics Department of PhysicsZhejiang University

An exact analytic expression for an ultrashort hollow-Airy wave packet is presented beyond the slowly varying envelope approximation. The hollow-Airy wave packet combines the hollow-Gaussian beam in the spatial domain and the Airy pulse in the temporal domain. The spatiotemporal propagation dynamics of the ultrashort hollow- Airy pulse are analyzed by the numerical simulations. During the propagation in free space, the spatial intensity profile evolves from hollow-Gaussian to Gaussian shape; the temporal intensity profile retains Airy shape over several Rayleigh ranges. The acceleration property of the ultrashort Airy pulse is also demonstrated.

关键词： Exact Evolution of Ultrashort Hollow-Airy Pulses in the Spatiotemporal Domain cycle

High contrast atomic magnetometer based on coherent population trapping

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Chinese physics B 2014年第2期23卷 477-480页

作者：杨爱林杨国卿徐云飞林强 Institute of optics Department of PhysicsZhejiang University

We present an experimental and theoretical investigation of the coherent population trapping （CPT） resonance excited on the D1 line of 87Rb atoms by bichromatic linearly polarized laser light. The experimental results show that a lin｜｜lin tran- sition scheme is a promising alternative to the conventional circular-circular transition scheme for an atomic magnetometer. Compared with the circular light transition scheme, linear light accounts for high-contrast transmission resonances, which makes this excitation scheme promising for high-sensitivity magnetometers. We also use linear light and circular light to detect changes of a standard magnetic field, separately.

关键词： high contrast atomic magnetometer coherent population trapping

A laser pump-re-pump atomic magnetometer

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Chinese physics B 2013年第12期22卷 177-181页

作者：杨爱林杨国卿蔡勋明徐云飞林强 Institute of optics Department of Physics Zhejiang University

We demonstrate experimentally an atomic magnetometer based on optical pumping theory, a magnetic resonance that is induced by a radio frequency field and dependent on the magnetic field strength. Compared with the conventional method using one radiation field, which is used not only as the probe beam but also as a pump beam, the additional re-pump beam can increase remarkably the amplitude of the signal. It is shown that the amplitude of the magnetic field resonance signal can increase more than 55% by using an additional re-pump beam, which makes the sensitivity of the magnetometer higher. Finally, we investigate the relation between amplitude of the signal and re-pump laser power, and calculate the atomic population in the trapping states with rate equations.

关键词： atomic magnetometer optical pumping sensitivity

Nonlinear Dust Acoustic Waves in Dissipative Space Dusty Plasmas with Superthermal Electrons and Nonextensive Ions

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Communications in Theoretical physics 2016年第5期65卷 606-612页

作者： A.M.El-Hanbaly E.K.El-Shewy M.Sallah H.F.Darweesh Theoretical physics research group Physics Department Faculty of Science Mansoura University department of physics Taibah University

The nonlinear characteristics of the dust acoustic(DA)waves are studied in a homogeneous,collisionless,unmagnetized,and dissipative dusty plasma composed of negatively charged dusty grains,superthermal electrons,and nonextensive *** pseudopotential technique has been employed to study the large amplitude DA ***(Sagdeev pseudopotential)has an evidence for the existence of compressive and rarefractive *** global features of the phase portrait are investigated to understand the possible types of solutions of the Sagdeev *** the other hand,the reductive perturbation technique has been used to study small amplitude DA waves and yields the Korteweg-de Vries-Burgers(Kd V-Burgers)equation that exhibits both soliton and shock *** behavior of the obtained results of both large and small amplitude is investigated graphically in terms of the plasma parameters like dust kinematic viscosity,superthermal and nonextensive parameters.

关键词： Sagdeev pseudopotential KdV-Burgers equation soliton and shock waves reductive perturbation dust kinematic viscosity

Generation of four-atom Greenberger-Horn-Zeilinger state via adiabatic passage

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Chinese physics B 2013年第5期22卷 141-146页

作者：张春玲陈美锋 Laboratory of Quantum optics Department of PhysicsFuzhou University

We propose a scheme to generate a Greenberger-Horn-Zeilinger （GHZ） state of four atoms trapped in a two-mode optical cavity via an adiabatic passage. The scheme is robust against moderate fluctuations of the experimental parameters. Numerical calculations show that the excited probabilities of both the cavity modes and the atoms are tiny and depend on the pulse peaks of the classical laser fields. For certain decoherence due to the atomic spontaneous emission and the cavity decay, there exits a range of pulse peaks to get a high fidelity.

关键词： Greenberger-Horn-Zeilinger (GHZ) state adiabatic passage cavity quantum electrodynamics

Engineering steady-state entanglement for two atoms held in separate cavities through laser cooling

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Chinese physics B 2014年第4期23卷 109-112页

作者：沈利托陈荣鑫吴怀志杨贞标 Laboratory of Quantum optics Department of Physics Fuzhou University

We propose a scheme to prepare the steady-state entanglement for two atoms, which are held in separate cavities that are coupled through a short optical fiber or optical resonator. The entangled steady-state with a high fidelity can be achieved even with a low cooperativity parameter, by making use of the driving laser fields. Such a cooling mechanism is based on a resonant laser pump of the unwanted ground states to the excited states, which finally decay to the desired steady-state.

关键词： laser cooling steady-state entanglement optical fiber

Optical forces on neutral atoms in the presence of fluctuating laser fields:numerical analysis

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Communications in Theoretical physics 2023年第1期75卷 130-137页

作者： Forough Bozorgzadeh Masoud Yousefi Mohsen Akbari physics department College of SciencesShiraz UniversityShirazIran Quantum optics group Iranian Center for Quantum Technologies(ICQT’s)TehranIran Quantum optics Lab Department of PhysicsKharazmi UniversityTehranIran

Doppler cooling of^(88)Sr atoms is studied in the presence of off-resonant red-detuned fluctuating laser *** a semi-classical approach,we show that the relevant physical quantities in the cooling process,such as optical forces,the damping coefficient,Doppler temperature,and atom number in the trap,are strongly affected by the laser amplitude and phase *** find that the Doppler cooling limit is higher than the predicted Doppler theory for non-fluctuating *** implies an additional heating mechanism exists due to the laser ***,our numerical analysis shows that the effect of laser power stability on reducing the number of trapped atoms in a magneto-optical trap is more substantial than the effect of laser linewidth.

关键词： force of light laser cooling and trapping laser fluctuations magneto-optical trap(MOT) phase diffusion two-level atom