Quantum interference effects on Fraunhofer diffraction in hybrid optomechanical cavity with three-level atomic system

The phenomenon of optical bistability is studied for the three-level atomic system in V-configuration confined in a unidirectional optical ring cavity, and the effects of quantum interference and coupling field are investigated. The possibility of obtaining optical multistability in the system by controlling quantum interference and coupling field strength is also discussed.

The effect of quantum interference on the optical properties of a pumped-probe three-level V-type atomic system is investigated. The probe absorption, dispersion, group index and optical bistability beyond the two-photon resonance condition are discussed. It is found that the optical properties of a medium in the frequency of the probe field, in general, are phase independent. The phase dependence arises from a scattering of the coupling field into the probe field at a frequency which in general differs from the probe field frequency. It is demonstrated that beyond the two-photon resonance condition the phase sensitivity of the medium will disappear.

Atomic coherence and interference manifested by electromagentically induced transparency (EIT) and coherent population trapping (CPT) plays an important role in the current studies of atom-photon interactions and has found numerous applications in optical physics. EIT is created in a three-level atomic system by a coupling field and results in destructive interference between two excitation paths of a weak probe laser interacting with the atomic medium. This leads to suppressed linear absorption and rapidly varying atomic dispersion for the probe laser near the atomic resonance, which provides the platform for a variety of applications such as nonlinear optics at low light levels, slow light manipulation, and quantum state engineering for photons and atoms. Here we extend the simple three-level EIT system to more complicated and versatile configurations in a multi-level atomic system coupled by multiple laser fields. We show that with multiple excitation paths provided by different laser fields, phase-dependent quantum interference is induced: either constructive or destructive interference can be realized by varying the relative phases among the laser fields. Two specific examples are discussed. One is a three-level system coupled by bichromatic coupling and probe fields, in which the phase dependent interference between the resonant two-photon Raman transitions can be initiated and controlled. Another is a four-level system coupled by two coupling fields and two probe fields, in which a double-EIT configuration is created by the phase-dependent interference between three-photon and one-photon excitation processes. We analyze the coherently coupled multi-level atomic system and discuss the control parameters for the onset of constructive or destructive quantum interference. We describe two experiments performed with cold Rb atoms that can be approximately treated as the coherently coupled three-level and four-level atomic systems respectively. The experimental results show the phase-dependent quantum coherence and interference in the multi-level Rb atomic system, and agree with the theoretical calculations based on the coherently coupled three-level or four-level model system.

We present discrimination of the effect of one-photon and two-photon coherences in electromagnetically induced transparency for a three-level ladder-type atomic system. After the optical Bloch equations for a three-level atom, with either cycling or non-cycling transitions, were solved numerically, the solutions were averaged over the velocity distribution and finite transit time. Through this we were able to discriminate one-photon and two-photon coherence parts of the calculated spectra. We also found that the spectra showed peaks as the branching ratio of the intermediate (excited) state increased (decreased). The experimental results of previous reports [H. S. Moon, et al., Opt. Express 16, 12163 (2008); H. S. Moon and H. R. Noh, J. Phys. B 44, 055004 (2011)] could well be accounted for by this discrimination of one-photon and two-photon coherences in the transmittance signals for the simplified three-level atomic system.

Theory of a quantum beat laser in a three-level cascade atomic system

Vortex beams have important applications in a number of physical fields such as optical information processing, optical imaging, etc. Nonreciprocal propagation of light often plays a key role in some occasions in these applications. In this work, we investigate the nonreciprocal propagation of a vortex beam using a far-off resonant Raman process in a Λ -type three-level thermal atomic system. The probe vortex can propagate with high transmission in the backward direction and be well isolated in the forward direction. Via adjusting the strong control field and the atom temperature, the forward transmission of the probe vortex can be further suppressed, and higher isolation can be achieved under the use of a controlled vortex with the same orbital angular momentum. This work may provide reference for experimental studies on the nonreciprocal transmission of vortex beams and find applications in vortex isolators and circulators.

We study the enhanced Kerr-nonlinear coefficient in a three-level A-type atomic system for various coupling-beam powers. The Kerr-nonlinear coefficient behaves very differently in the strong and the weak coupling power regions and changes sign when the coupling or probe frequency detuning changes sign. Comparisons of Kerr-nonlinear coefficients as functions of probe frequency detuning, coupling power, and coupling frequency detuning are presented.

Role of strongly modulated coherence in transient evolution dynamics of probe absorption in a three-level atomic system

Nonreciprocal optical bistability based on Doppler effect in a three-level atomic system

We measure the Kerr-nonlinear index of refraction of a three-level Lambda-type atomic system inside an optical ring cavity. The Kerr nonlinearity is modified and greatly enhanced near atomic resonant conditions for both probe and coupling beams. The Kerr nonlinear coefficient n(2) changes sign when the coupling beam frequency detuning switches sign, which can lead to interesting applications in optical devices such as all-optical switches.

In this paper, we investigated electromagnetically induced grating in a three-level atomic system via relative phase between applied lights. The three-level atomic system interacts with a weak probe light, a signal light and a strong standing wave coupling light in two-dimensional directions. We realized that Fraunhofer diffraction pattern can be obtained by tuning the intensity and detuning’s of the coupling light. We also use of optical vortex light instead of optical plane wave and found that the asymmetric diffraction pattern can be obtained via orbital angular momentum (OAM), respectively. We also studied the different orders of the diffraction pattern versus relative phase of applied lights for different number of OAM.

This paper studies the optical bistability in a degenerate three-level Λ-type atomic system in a unidirectional optical ring cavity. The effect of quantum interference on the phase control of the optical bistabilty is then discussed. It is shown that the optical bistability changes with the intensity of coupling and the rate of an incoherent pumping field. The possibility of creating an optical multistability (OM) by the intensity of coupling field relative phase between the applied fields, and the rate of an incoherent pump field has also been discussed.

The Hamiltonians of two- and three-level atomic systems interacting with nearly resonant electro-magnetic fields are described. The geometric phase related to the σ z operator of a two-level system is analysed and it is shown that this phase is well defined also for an open circuit. For a closed circuit this phase becomes equivalent to twice the Berry phase. For three-level atomic system the eigenenergies of the Hamiltonian are obtained by solving a cubic equation. Simplified forms for these eigenenergies and a condition for degeneracy are obtained. For non-degenerate three-level system geometric phases related to Cartan subalgebra are analysed under the adiabatic approximation and their relations with the three-level Berry phases are clarified. We show how to use the general theory of non-Abelian connections to the Hamiltonian of a three-level atomic system which includes a degeneracy.

We analyze theoretically a simple and consistent quantum mechanical model that reveals the possible role of quantum interference, protein noise, and sink effects in the nonphotochemical quenching (NPQ) in light-harvesting complexes (LHCs). The model consists of a network of five interconnected sites (excitonic states of light-sensitive molecules) responsible for the NPQ mechanism. The model also includes the "damaging" and the dissipative channels. The damaging channel is responsible for production of singlet oxygen and other destructive outcomes. In our model, both damaging and "dissipative" charge transfer channels are described by discrete electron energy levels attached to their sinks, that mimic the continuum part of electron energy spectrum. All five excitonic sites interact with the protein environment that is modeled using a stochastic process. Our approach allowed us to derive the exact and closed system of linear ordinary differential equations for the reduced density matrix and its first momentums. These equations are solved numerically including for strong interactions between the light-sensitive molecules and protein environment. As an example, we apply our model to demonstrate possible contributions of quantum interference, protein noise, and sink effects in the NPQ mechanism in the CP29 minor LHC. The numerical simulations show that using proper combination of quantum interference effects, properties of noise, and sinks, one can significantly suppress the damaging channel. Our findings demonstrate the possible role of interference, protein noise, and sink effects for modeling, engineering, and optimizing the performance of the NPQ processes in both natural and artificial light-harvesting complexes.

Quantum interference effects in the unmodulated quantum systems with light-matter interaction have been widely studied, such as electromagnetically induced transparency (EIT) and Autler-Townes splitting (ATS). However, the similar quantum interference effects in the Floquet systems (i.e., periodically modulated systems), which might cover rich new physics, were rarely studied. In this article, we investigate the quantum interference effects in the Floquet two- and three-level systems analytically and numerically. We show a coherent destruction tunneling effect in a lotuslike multipeak spectrum with a Floquet two-level system, where the intensity of the probe field is periodically modulated with a square-wave sequence. We demonstrate that the multipeak split into multiple transparency windows with tunable quantum interference if the Floquet system is asynchronously controlled via a third level. Based on phenomenological analysis with Akaike information criterion, we show that the symmetric central transparency window has a similar mechanism to the traditional ATS or EIT depending on the choice of parameters, additional with an extra degree of freedom to control the quantum interference provided by the modulation period. The other transparent windows are shown to be asymmetric, different from the traditional ATS and EIT windows. These nontrivial quantum interference effects open up a scope to explore the applications of the Floquet systems.