arXiv subjects

Cheng-Long Jia

Publications and source records attributed to Cheng-Long Jia.

4 recordsLinked to original sources

arXiv2011

Fast optical control of spin dynamics in a quantum wire

The spin dynamics in a quantum wire with a Rashba spin orbit interaction (SOI) is shown to be controllable via sub-picosecond electromagnetic pulses shaped appropriately. If the light polarization vector is along the wire's direction, the carriers experience a momentum boost while the phase coherence in different spin channels is maintained, a fact exploitable to control the speed of a photo-driven spin field effect transistor. A photon pulse with a polarization vector perpendicular to the wire results in a spin precession which is comparable to that due to the Rashba SOI and is tunable by the pulse field parameters, an effect utilizable in optically controlled spintronics devices.

cond-mat.mes-hall↗

arXiv2005

Production of squeezed state of single mode cavity field by the coupling of squeezed vacuum field reservoir in nonautonomous case

The dissipative and decoherence properties as well as the asymptotic behavior of the single mode electromagnetic field interacting with the time-dependent squeezed vacuum field reservoir are investigated in detail by using the algebraic dynamical method. With the help of the left and right representations of the relevant $hw(4)$ algebra, the dynamical symmetry of the nonautonomous master equation of the system is found to be $su(1,1)$. The unique equilibrium steady solution is found to be the squeezed state and any initial state of the system is proved to approach the unique squeezed state asymptotically. Thus the squeezed vacuum field reservoir is found to play the role of a squeezing mold of the cavity field.

quant-ph↗

arXiv2005

Dynamical symmetry and analytical solutions of the non-autonomous quantum master equation of the dissipative two-level system: decoherence of quantum register

Based on the non-autonomous quantum master equation, we investigate the dissipative and decoherence properties of the two-level atom system interacting with the environment of thermal quantum radiation fields. For this system, by a novel algebraic dynamic method, the dynamical symmetry of the system is found, the quantum master equation is converted into a Schrödinger-like equation and the non-Hermitian rate (quantum Liouville) operator of the master equation is expressed as a linear function of the dynamical u(2) generators. Furthermore, the integrability of the non-autonomous master equation has been proved for the first time. Based on the time-dependent analytical solutions, the asymptotic behavior of the solution has been examined and the approach to the equilibrium state has been proved. Finally, we have studied the decoherence property of the multiple two-level atom system coupled to the thermal radiation fields, which are related to the quantum register.

quant-ph↗

arXiv2005

A two-level atom coupled to a controllable squeezed vacuum field reservoir

The dissipative and decoherence properties of the two-level atom interacting with the squeezed vacuum field reservoir are investigated based on the nonautonomous master equation of the atomic density matrix in the framework of algebraic dynamics. The nonautonomous master equation is converted into a Schrödinger-like equations and its dynamical symmetry is found based on the left and right representations of the relevant algebra. The time-dependent solution and the steady solution are obtained analytically. The asymptotic behavior of the solution is examined and the approach to the equilibrium state is proved. Based on the analytic solution the response of the system to the squeezed vacuum field reservoir is studied numerically.

quant-ph↗