Coherent and Incoherent Optical Processes and Phase Sensitive Adiabatic States

Wojciech Gawlik

Kang Shen, Fei Wang

In this paper, we investigate the effects of incoherent pumping on quantum correlations in a Λ -type atomic system driven by coherent and incoherent fields simultaneously. With the adiabatic elimination treatment, we show that the stable “one-way” Einstein–Podolsky–Rosen (EPR) steering is generated without the requirement of good cavity limitation. More interestingly, the asymmetrical EPR steering is simply controlled by the polarized angle of the incoherent field. The internal mechanisms can be understood based on dressed-state representation, in which the population differences are strongly modified by the quantum interference from incoherent pumping. The phase-sensitive quantum correlations in the present scheme may find potential applications in quantum information processing.

Ferruccio Renzoni, Stig Stenholm

Ahmed H. Zewail

A new technique is presented for measuring the incoherent resonance decay (IRD) and the coherent optical ringing of selectively (5 MHz) prepared electronic states. The method utilizes electro-optic switching of a single laser mode that is on or off resonance with respect to the homogeneous molecular packets in the excited ensemble. The technique was applied to a variety of systems (gases at low pressures, gases at relatively high pressures, and solids at low temperatures) to give information about their phase memory (optical T2 processes), radiative and radiationless decay (optical T1 processes), and to measure directly their optical transition moment between the ground state and the prepared electronic state. The theory of coherent and incoherent states is also given.

Sintayehu Tesfa

Miaodi Guo, Haifeng Li, Feng-Lei Wang +2 more

Coherent perfect absorption (CPA) or reflection (CPR) are methods to realize the extreme manipulation on an optical field. We propose a scheme to operate a bistable switch with convertible CPA and/or CPR. Generally, CPA and CPR occur with different input-field phases. For example, CPA is realized when two input probe beams are in phase; instead, CPR is achieved when they are out of phase. In this scheme, a CPA state can be converted to a CPR state by an incoherent field although two input fields are in phase. When we use the incoherent field as a switching field, the CPA (CPR) state is treated as the closed (open) state. As a result, the switching efficiency can theoretically reach a maximum value, i.e., η = 1. In addition, the switch can be operated in the linear regime with a weak input field, and in the nonlinear or bistable regime with a strong input field. Moreover, the efficiency of the bistable switch is sensitively dependent on the input-field intensity. It provides a potential application of this work on sensitive optical detecting.