Five-level Atom Research Articles

Dynamical evolution of a five-level atom interacting with an intensity-dependent coupling regime influenced by a nonlinear Kerr-like medium

We present an analytical solution for a quantum system characterized by a double Λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda$$\\end{document} five-level atom interacting with an intensity-dependent coupling regime, influenced by a nonlinear Kerr-like medium. We also derive the constants of motion through Heisenberg’s equations. Furthermore, the dynamical evolution of the entanglement and quantum coherence between the atom and the field is discussed using linear entropy and l1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$l_{1}$$\\end{document}-norm of coherence. Through a comprehensive examination of the quantum system, it is observed that both the detuning and the Kerr-like parameters exert a significant impact on the degree of entanglement and coherence. However, the impacts of detuning and the Kerr effect become less pronounced when the photon multiplicity is high. In addition, we conduct a comparison between the five-level atomic system and a four-level system, revealing that the number of energy levels has a profound impact on the behavior of entanglement and coherence. These findings highlight the importance of atomic structure and photon multiplicity in controlling and optimizing quantum processes, particularly in applications involving quantum communication and information processing.

Enhanced negative refraction in one- and two-dimensional chiral atomic lattices

We consider a physical scheme for the realization of optical lattices that have negative refracting under certain conditions. The lattice is formed by clusters of five-level closed-loop chiral atoms assumed to have a Gaussian density distribution in dipole traps along one or two dimensions. With a suitable combination of strong standing wave control fields, spatial symmetry of atoms is achieved. Besides, the dispersion properties of an atomic lattice can be modified conveniently by adjusting various parameters related to the atoms or the lattice. We show that negative-like refraction is not specific to the atoms themselves, but also emerges due to the periodicity of the lattice. We further reveal that the refraction is negative over specific regions on the lattice and strongly depends on the number of atoms trapped along a particular direction. Our model is effectively controllable remotely and may have applications in negative refraction devices and optical information processing.

Quantum coherence and entanglement of the system of a five-level atom in the presence of nonlinear fields

We investigate the atom-field system in the framework of harmonic oscillators based on deformed Heisenberg algebras. We explore the dynamic characteristics of the considered system under the effect of a nonlinear field. In particular, we consider the atomic population, atomic coherence, and atom-field entanglement for a system that comprises a single five-level atom interacting with a single-mode nonlinear field when the deformation effect is taken into account. We examine the time evolution of the quantum quantifiers in the presence of deformation when the initial state of the quantized field is defined to be a nonlinear coherent state (CS) or a superposition state.

On the interaction between Λ-type five-level atom and one-mode squeezed coherent field

This article investigates the effect of the detuning interaction parameters of a single-mode electromagnetic field with a five-level Λ-type. The differential system is solved in the presence of detuning parameter under the initial conditions when the atom and field are prepared in an excited and squeezed state, respectively. The non-classical properties of the field initially in the squeezed coherent states based on the evolution of the second-order correlation function. The study of entanglement between parts of a quantum system is done through the von Neumann entropy. We analyze the effect of the squeeze and detuning parameters on the dynamics of some field aspects and non-local correlation. The results obtained from this study show that the detuning parameter has an essential impact on the field properties.

Spatial Manipulation via Four-Wave Mixing in Five-Level Cold Atoms

In a recent publication [S. Gan, Laser Phys. 31, 055401 (2021)], a scheme for controlling the vortex four-wave mixing (FWM) in a five-level atomic system has been put forward. Based on this work, we propose a new scheme for the spatial manipulation via four-wave mixing in a five-level atomic system when the radial index is considered. It is found that the phase and intensity of the FWM field can be spatially manipulated. More importantly, we show the superposition modes created by the interference between the FWM field and a same-frequency Gaussian beam, which can also be controlled via the corresponding parameters. Our research is helpful to understand and manipulate optical vortices and can be widely used in quantum computation and communication.

Coherent and incoherent laser pump on a five-level atom in a strongly coupled cavity-QED system

We propose a cavity quantum electrodynamic system consisting of a five-level atom coupled to a single mode of the cavity electromagnetic field. The study is focused on the regime of strong coupling between the cavity and atom. Pump laser fields and cavity fields connect the split energy levels of the atom. Instead of the well-known two-level Dicke model obtained by adiabatic elimination of the high-energy levels, we consider the pump lasers' detunings to the atomic transitions to be very small such that we can examine the influence of the higher-energy states. We have studied the effect of an external coherent drive and incoherent pumping on these higher-energy levels and observed the enhancement of intracavity photon numbers due to quantum coherence effects. The amplification of intracavity photons is achieved even without a population inversion. However, the effect of the coherent and incoherent drive is negligible for very large detunings when the higher-energy states are adiabatically eliminated. At zero and small detunings, the system reaches the steady state at an earlier instant of time for higher incoherent pumping. We find an almost agreeable steady-state behavior of the system's exact full quantum dynamics model and its semiclassical approximation. Our model tries to accurately simulate the open system by considering the cavity decay, spontaneous decay, and dephasing of the system.

The Interaction between M-Configuration Five-Level Atom and a Single Mode Cavity Field

The Interaction between M-Configuration Five-Level Atom and a Single Mode Cavity Field

Spatially dependent hyper-Raman scattering in five-level cold atoms.

We demonstrate a scheme to control the spatially dependent hyper-Raman scattering based on electromagnetically induced transparency in a cold atomic system. By adjusting the different system parameters, one can effectively modulate the phase and intensity of the generated Raman field. Specifically, we show that electromagnetically induced transparency creates quantum interference, which results in greatly enhanced efficiency for the generated Raman field. Such improvement in Raman efficiency makes our scheme suitable for generation of short-wavelength coherent radiation, conversion of frequency, and nonlinear spectroscopy based on orbital angular momentum light.

Properties of Pancharatnam Phase and Entanglement of a Five-Level Atom Interacting with a Squeezed Field

We introduce a quantum scheme where a single five-level atom interacts with a single-mode cavity field by a time-dependent coupling. During the interaction, the temporal behavior of the quantum entropy in the atomic basis is compared with that of the Mandel parameter used to quantify the nonclassical properties of the field. With the field prepared in a squeezed coherent state, the atomic quantum entropy is then used to quantify the entanglement or the nonlocal correlation of the five-level atom (5 LA) – field system. The influence of one- and two-photon transitions and the atomic motion on the degree of entanglement and the Pancharatnam phase is analyzed. The analysis emphasizes that both the time dependence and photon multiplicity play an important role in the evolution of the degree of entanglement, the Pancharatnam phase, and nonclassical properties. This insight may be very useful in various applications in quantum physics and quantum optics.

Tunable single-photon diode and circulator via chiral waveguide–emitter couplings

We propose a scheme to realize a single-photon diode and circulator using two waveguides chirally coupled to a five-level M-type atom. Two external control fields are introduced to drive the emitter. Non-reciprocal single-photon propagation can be completed in our scheme, which underpins the single-photon diode and circulator. The single-photon diode can work well at special frequency points of the incident photon simultaneously. We can modulate the Rabi frequencies and detunings of the control fields to satisfy various values of frequency points of the incident photon. In addition, the non-reciprocity of the photon propagation can be turned off or on when the control fields are turned off or on. A single-frequency filter can filter out a special frequency for the incident photon by adjusting the detunings of the control fields. The single-photon circulator can realize photon propagation in the pathways with probability 100%. The properties of the circulator can be modulated by adjusting the Rabi frequencies and detunings of the control fields.

Non-thermal hydrogen Lyman line and continuum emission in solar flares generated by electron beams

Aims. Hydrogen Lyman continuum emission is greatly enhanced in the impulsive kernels of solar flares, with observations of Lyman lines showing impulsive brightening and both red and blue wing asymmetries, based on the images with low spatial resolution. A spate of proposed instruments will study Lyman emission in more detail from bright, impulsive flare kernels. In support of new instrumentation we aim to apply an improved interpretation of Lyman emission with the hydrodynamic radiative code, HYDRO2GEN, which has already successfully explained Hαemission with large redshifts and sources of white light emission in solar flares. The simulations can interpret the existing observations and propose observations in the forthcoming missions.Methods. A flaring atmosphere is considered to be produced by a 1D hydrodynamic response to injection of an electron beam, defining depth variations of electron and ion kinetic temperatures, densities, and macro-velocities. Radiative responses in this flaring atmosphere affected by the beams with different parameters are simulated using a fully non-local thermodynamic equilibrium (NLTE) approach for a five-level plus continuum model hydrogen atom with excitation and ionisation by spontaneous, external, and internal diffusive radiation, and by inelastic collisions with thermal and beam electrons. Integral radiative transfer equations for all optically thick transitions are solved using the L2 approximation simultaneously with steady state equations.Results. During a beam injection in the impulsive phase there is a large increase of collisional ionisation and excitation by non-thermal electrons that strongly (by orders of magnitude) increases excitation and the ionisation degree of hydrogen atoms from all atomic levels. These non-thermal collisions combined with plasma heating caused by beam electrons lead to an increase in Lyman line and continuum radiation, which is highly optically thick. During a beam injection phase the Lyman continuum emission is greatly enhanced in a large range of wavelengths resulting in a flattened distribution of Lyman continuum over wavelengths. After the beam is switched off, Lyman continuum emission, because of its large opacity, sustains, for a very long time, the high ionisation degree of the flaring plasma gained during the beam injection. This leads to a long enhancement of hydrogen ionisation, occurrence of white light flares, and an increase of Lyman line emission in cores and wings, whose shapes are moved closer to those from complete redistribution (CRD) in frequencies, and away from the partial ones (PRD) derived in the non-flaring atmospheres. In addition, Lyman line profiles can reflect macro-motions of a flaring atmosphere caused by downward hydrodynamic shocks produced in response to the beam injection reflected in the enhancements of Ly-line red wing emission. These redshifted Ly-line profiles are often followed by the enhancement of Ly-line blue wing emission caused by the chromospheric evaporation. The ratio of the integrated intensities in the Lyαand Lyβlines is lower for more powerful flares and agrees with reported values from observations, except in the impulsive phase in flaring kernels which were not resolved in previous observations, in which the ratio is even lower. These results can help observers to design the future observations in Lyman lines and continuum emission in flaring atmospheres.

Amplitude and phase controlled absorption and dispersion of coherently driven five-level atom in double-band photonic crystal**Project supported by the National Natural Science Foundation of China (Grant Nos. 11447232 and 11204367).

The absorption–dispersion properties of a microwave-driven five-level atom embedded in an isotropic photonic bandgap (PBG) have been studied. Due to the singular density of modes (DOM) in the isotropic PBG and the dynamically coherence induced by the coupling fields, modified reservoir-induced transparency and quantum interference-induced transparency emerge simultaneously. Their interaction leads to ultra-narrow spectral structure. As a result of closed-loop configuration, these features can be manipulated by the amplitudes and relative phase of the coherently driven fields. The position and width of PBG also have an influence on the spectra. The theoretical studies can provide us with more efficient methods to control the atomic absorption–dispersion properties, which have applications in optical switching and slow light.

Realization of the Programmable Logical Atomic Gate

The simple realization of a three-bit programmable atomic gate on a five-level atom is demonstrated. The proposed scheme is based on an adiabatic transfer of the populations of atomic levels in the M-system. A detailed analysis of the numerical solution of nonstationary equations for the density matrix of the five-level system is carried out.

Manipulating multi-frequency light in a five-level cascade-type atomic medium associated with giant self-Kerr nonlinearity

We propose a model to manipulate group velocity of a multi-frequency probe light in an electromagnetically induced transparency medium consisting of five-level cascade-type atoms associated with a giant self-Kerr nonlinearity. An analytic expression of group index for the probe light is derived as a function of parameters of the probe and coupling fields, atomic density, and lifetimes of excited atomic states. In the presence of the self-Kerr, both probe and controlling fields can be used as knobs to manipulate the probe light between the subluminal and superluminal propagation modes in three separated frequency regions. The theoretical model agrees with experimental observation, and it is helpful to find the optimized parameters and related applications. Furthermore, by using such a cascade excitation scheme, it could be possible to choose the uppermost excited electronic states having long lifetimes, as Rydberg states, to slow the light down to a few mm/s.

QuTiP-package applications to five-level atom with one mode

In this poster, we apply the Quantum Toolbox in Python (QuTiP) to study the interaction between a five-level atom and a single-mode cavity field. The non-classical statistical aspects such as the Mandel Q parameter, squeezing parameter, and linear entropy are investigated.

The Dynamics of a Five-level (Double Λ)-type Atom Interacting with Two-mode Field in a Cross Kerr-like Medium

In this paper, we propose a new transition scheme (Double Λ) for the interaction between a five-level atom and an electromagnetic field and study its dynamics in the presence of a cross Kerr-like medium in the exact-resonance case. The wave function is derived when the atom is initially prepared in its upper most state, and the field is initially prepared in the coherent state. We studied the atomic population inversion, the coherence degree by studying the second-order correlation function, Cauchy-Schwartz inequality (CSI) and the relation with P-function. Finally, we investigate the effect of Kerr-like medium on the evolution of Husimi Q-function of the considered system.

Dynamic generation and coherent control of beating stationary light pulses by a microwave coupling field in five-level cold atoms

We propose an efficient scheme for generating and controlling beating stationary light pulses in a five-level atomic sample driven into electromagnetically induced transparency condition. This scheme relies on an asymmetrical procedure of light storage and retrieval tuned by two counter-propagating control fields where an additional coupling field, such as the microwave field, is introduced in the retrieval stage. A quantum probe field, incident upon such an atomic sample, is first transformed into spin coherence excitation of the atoms and then retrieved as beating stationary light pulses exhibiting a series of maxima and minima in intensity due to the alternative constructive and destructive interference. It is convenient to control the beating stationary light pulses just by manipulating the intensity and detuning of the additional microwave field. This interesting phenomenon involves in fact the coherent manipulation of dark-state polaritons and could be explored to achieve the efficient temporal splitting of stationary light pulses and accurate measurement of the microwave intensity.

Two-dimensional atom localization based on coherent field controlling in a five-level M-type atomic system.

We study two-dimensional sub-wavelength atom localization based on the microwave coupling field controlling and spontaneously generated coherence (SGC) effect. For a five-level M-type atom, introducing a microwave coupling field between two upper levels and considering the quantum interference between two transitions from two upper levels to lower levels, the analytical expression of conditional position probability (CPP) distribution is obtained using the iterative method. The influence of the detuning of a spontaneously emitted photon, Rabi frequency of the microwave field, and the SGC effect on the CPP are discussed. The two-dimensional sub-half-wavelength atom localization with high-precision and high spatial resolution is achieved by adjusting the detuning and the Rabi frequency, where the atom can be localized in a region smaller thanλ/10×λ/10. The spatial resolution is improved significantly compared with the case without the microwave field.

Dynamic evolution of double $$\Lambda $$ Λ five-level atom interacting with one-mode electromagnetic cavity field

In this paper, the model describing a double $$\Lambda $$ five-level atom interacting with a single mode electromagnetic cavity field in the (off) non-resonate case is studied. We obtained the constants of motion for the considered model. Also, the state vector of the wave function is given by using the Schrodinger equation when the atom is initially prepared in its excited state. The dynamical evolutions for the collapse revivals, the antibunching of photons and the field squeezing phenomena are investigated when the field is considered in a coherent state. The influence of detuning parameters on these phenomena is investigated. We noticed that the atom–field properties are influenced by changing the detuning parameters. The investigation of these aspects by numerical simulations is carried out using the Quantum Toolbox in Python (QuTip).

Observation of polariton resonances with five-level M-type atoms in an optical cavity

We study the polariton resonances with the five-level M-type atoms inside an optical cavity through the observation of the cavity transmission spectrum. The ultranarrow peaks associated with the dark-state polaritons in the system can be achieved by adjusting three coupling fields. Simple theory analysis and numerical simulations are also presented.