Three-level Atomic System Research Articles

Superposition of standing waves induced ultra high-resolution atom localization

Abstract In this study, we have theoretically demonstrated ultra-high resolution two-dimensional atom localization within a three-level $\lambda$-type atomic medium via superposition of asymmetric and symmetric standing wave fields. Our analysis provides understanding into the precise spatial localization of atomic positions at the atomic level, utilizing advanced theoretical approaches and principles of quantum mechanics. The dynamical behavior of a three-level atomic system is thoroughly analyzed using the density matrix formalism within the realm of quantum mechanics. A theoretical approach is constructed to describe the interaction between the system and external fields, specifically a control field and a probe field. The absorption spectrum of the probe field is thoroughly examined to clarify the spatial
localization of the atom within the proposed configuration. We have theoretically investigated that symmetric and asymmetric superposition phenomena significantly influence the localized peaks within a two-dimensional spatial domain. Specifically, the emergence of one and two sharp localized peaks has been observed within a region of one wavelength domain. We observed notable influences of the intensity of the control field, probe field detuning, and decay rates on atom localization. Ultimately, we have achieved an unprecedented level of ultra-high resolution and precision in localizing an atom within an area smaller than λ/35×λ/35. These findings hold promise for potential applications in domains such as Bose-Einstein condensation, nanolithography, laser cooling, trapping of neutral atoms, and the measurement of center-of-mass wave-functions.

Electromagnetically induced grating via amplitude and phase modulations in a three-level V-type atomic medium

Abstract A probe laser beam can be completely absorbed in an atomic resonance frequency region, however, if a coupling laser beam is further applied to the atom, the atomic medium can exhibit electromagnetically induced transparency (EIT), i.e, the probe beam can be completely transmitted through the atomic medium. Thus, if the coupling beam is a standing wave field with nodes and antinodes, it will cause in space a periodic modulation of the transmitted spectrum of the probe field. This means that the probe field propagates through the atomic medium just as it passes through a diffraction grating which is called electromagnetically induced grating (EIG). Based on amplitude or phase modulation of transmission function, the absorption grating or the phase grating can be formed, respectively. In this work, based on controllable absorption and dispersion properties of a three-level V-type atomic system, we study the control of the absorption grating and the phase grating with respect to the intensity and the frequency of the laser fields. The absorption diffraction pattern at the two-photon resonance is obtained, while the phase diffraction pattern appears when there is a frequency shift of either the coupling frequency or the probe frequency compared to the corresponding atomic resonance frequency. By adjusting the coupling or/and probe laser frequency, the absorption grating can be converted into the phase grating and the high-order diffraction efficiency can also be improved.

Enhanced optical pumping using mutually orthogonal magnetic fields for quantum sensing

The atomic population trapped in irrelevant atomic states is a limiting factor for sensors based on laser-atom interaction. Using a bi-chromatic light field along with a specific combination of magnetic fields, we show a significant increase in the amplitude (i.e., more than seven times) of a two-photon coherent population trapping (CPT) resonance, which can be effectively used for atomic magnetometry. This increase in amplitude can be explained through enhanced optical pumping via the transfer of population to the relevant Zeeman states. Our experimental observations are consistent with the theoretical calculations carried out for a realistic three-level atomic system using density matrix formalism. We further discuss the optimum condition for enhanced optical pumping by adjusting the ground-state decoherence rate. Enhanced optical pumping through the manipulation of the magnetic field is quite important and is of great interest in the field of quantum technology.

Coherent modulation of intense XUV pulses by ground-state coupling

We present and validate a method to modify the interaction between laser fields and an atomic three-level system based on the control of the ground state, which is interpreted with a direct analytical formula. Coherent modulation of intense extreme Ultraviolet (XUV) pulses is achieved by using near-infrared (NIR) lasers as control pulses interacting with the atomic systems, i.e. quantum transition paths are manipulated in light-matter interactions caused by the laser. We analyze the feasibility of realizing the phase reversal of the dipole response in the three-level system by controlling the interaction between the ground state and another excited state. The discussion of the modulation of intense XUV pulses complements recent studies relying on perturbative excitation. These observations provide new insights for achieving pulse shaping of the XUV frequency range by using the NIR pulse as a control pulse.

Investigation of diffraction grating in three-level gain medium

This research investigates the modulation of diffraction intensity distributions in both one- and two-dimensional scenarios within a three-level atomic system. The study employs a partially coherent light beam as the probe field, engaging with the atomic medium. Additionally, a control field capable of generating a standing wave is introduced. Analysis reveals that various parameters, including spatial coherence, beam width, and mode index of the partially coherent light, exert influence on the diffraction intensity distribution. The presence of a microwave field in the three-level atom is also considered, impacting the diffraction intensity distribution. Remarkably, the study observes that altering parameters such as microwave field strength and beam width of the partially coherent light results in the maximum energy of the probe field being transferred to higher orders, concurrently minimizing the central intensity. This distinctive method allows for the manipulation of diffraction intensity distribution through external control parameters. The proposed theoretical framework for creating a diffraction grating presents a novel avenue for experiment.

Vortex beam induced spatial modulation of quantum-optical effects in a coherent atomic medium

We have studied two-dimensional absorption, gain, and corresponding refractive index profiles in a ladder-type three-level atomic system interacting with three coherent fields. One is a weak probe field considered as a plane wave, while the other two are the control fields taken as two Laguerre–Gaussian doughnut beams. Position dependence of two vortex beams induces the spatially modulated coherence at the condition of resonance, which enables us to obtain space-dependent absorption, transparency, gain without inversion (GWI), and refractive index enhancement in the present scheme. The azimuthal modulation of coherence effects is attributed to the presence of optical angular momentum of the vortex beams. Under the influence of an additional travelling wave field with the presence of two vortex beams, the present model leads us to obtain an ultra-large enhancement of refractive index at the resonant detuning of the fields. This phenomenon makes the atom-field system to play the equivalent role of a high-refractive-index prism. The role of near dipole–dipole (NDD) interaction on the modulation of position-dependent coherence effects has also been investigated. It has been shown that, without any inclusion of the travelling wave field in the system, the phenomenon of resonant enhancement of refractive index may also occur in the presence of NDD effect. The new way of generating spatially controlled GWI and nonlinear refractive index enhancement is specific to the present model. This work seems to be useful for finding its applications in spatially modulated coherence controlled electromagnetically induced transparency-based quantum devices like quantum optical memory, switches, and quantum logic gates, where the refractive index switching phenomenon is a prerequisite.

Gain-assisted quantum heat engine based on electromagnetically induced transparency

We propose a scheme to realize a gain-assisted quantum heat engine (QHE) based on electromagnetically induced transparency (EIT), which consists of a three-level Λ-type atomic system interacting with two thermal reservoirs and a coupling field. The gain without inversion is induced to the system via spontaneously generated coherence (SGC) between two lower levels. The SGC has significantly affect on the system’s dynamics, resulting in an enhancement of the emission cross-section and spectral brightness of the QHE.

Goos–Hänchen shifts in a V-type three-level atomic system interacting with squeezed vacuum

This study explores the Goos–Hänchen (GH) shift phenomenon within a cavity hosting a V-type three-level atomic system, engaged with two independent broadband squeezed baths. Our exploration encompasses a thorough analysis of the lateral shifts in both reflected and transmitted light beams, with a focus on the impact of critical factors, i.e, coupling field strength, incoherent pumping field strength, and squeezed vacuum intensity. Our results reveal an interplay of these parameters, resulting in distinctive negative and positive GH shifts in both reflected and transmitted light. In addition, a remarkable enhancement of GH shifts at specific angles of incidence is observed, presenting a wide-ranging modulation across diverse system parameters. This study not only enriches the understanding of the GH shift in complex atomic systems but also highlights the potential for the manipulation of these lateral shifts by fine-tuning key variables of the system, and contributes valuable insights to the broader field of optical phenomena in quantum systems.

Phase and detuning control of the unidirectional reflection amplification based on the broken spatial symmetry.

In order to achieve the tunable unidirectional reflection amplification in a uniform atomic medium that is of vital importance to design high-quality nonreciprocal photonic devices, we propose a coherent closed three-level Δ-type atomic system by applying a microwave field, and a strong coupling field of linear variation along the x direction to control a probe field. In our scheme, the linearly increased coupling field destroys the spatial symmetry of probe susceptibility and effectively suppresses the reflection of one side; the microwave field constructs closed loop transitions to amplify the probe field and causes phase changes. The numerical simulation indicates that the unidirectional reflection amplification is sensitive to the relative phase ϕ and the coupling detuning Δc. Our results will open a new route toward harnessing optical non-reciprocity, which can provide more convenience and possibilities in the experimental realization.

Controllable optical bistability and multistability in a V-type three-level atomic system interacting with two broadband independent squeezed baths

In this study, we investigate the optical bistability (OB) and optical multistability (OM) phenomena within a V-type three-level atomic system interacting with two independent broadband squeezed baths confined in a unidirectional cavity. Our analysis reveals that the transition between OB and OM is influenced by the strength of the control field and the intensity of the squeezed vacuum. Notably, the impact of each of these factors on the transition exhibits distinct characteristics. Furthermore, we explore the effects of additional system parameters, such as the incoherent pumping rate and cooperation parameter. Our findings emphasize the crucial roles played by these parameters in shaping the observed results. Specifically, we observe that variations in the incoherent pumping rate and cooperation parameter contribute significantly to the system’s OB and OM behavior, further underscoring the multifaceted nature of the studied atomic system. This comprehensive investigation not only elucidates the intricate interplay between key parameters but also unveils the sensitivity of the system to variations in control field strength, intensity of the squeezed vacuum, incoherent pumping rate, and cooperation parameter.

Dynamic all-optical memory switching based on atomic optical bistable behavior in a three level Λ-type atomic system

We theoretically investigate the atomic optical bistability (AOB) in a three-level Λ-type atomic system confined in a unidirectional optical ring cavity. The role of the intensity or detuning of the control field on AOB is explored, and results show that absorption, dispersion, and nonlinearity can be modified significantly by the control field due to quantum coherence and interference in multilevel atomic systems. Thus, tuning the intensity or detuning of the control field can manipulate the switch-up and switch-down thresholds, as well as the area of the bistable hysteresis loop. According to the controllability of AOB, we design various schemes to realize dynamical all-optical switching between the high and low outputs of two bistable curves for a fixed cavity input. In addition, dynamical all-optical memory switching can be implemented by adding a pulse sequence for the intensity or detuning of the control field. For appropriate parameters, such as the cooperative coefficient, the extinction ratio of the switching can be improved dramatically.

Effect of phase fluctuations on atomic Talbot images in three-level ladder-type atomic system

In this article, we study the atomic Talbot effect in a three-level ladder-type atomic system, which consists of a strong microwave field having a finite bandwidth and a weak probe field. The upper levels are coupled with a strong position-dependent microwave field, while a weak probe field interacts with lower levels of the atomic system. We find that phase fluctuations associated with a strong microwave field significantly affect the transmission and corresponding intensity of Talbot images. We show that the choice of various parameters is crucial in the presence of phase fluctuation. An appropriate choice along with a pump field can still improve the intensity of atomic Talbot images. We believe that our results are useful for any practical situation where the effects of phase fluctuations are important.

High-fidelity Rydberg controlled-Z gates with optimized pulses

High-fidelity controlled-Z (CZ ) gates are essential and mandatory to build a large-scale quantum computer. In neutral atoms, the strong dipole–dipole interactions between their Rydberg states make them one of the pioneering platforms to implement CZ gates. Here we numerically investigate the optimized pulses to generate a high-fidelity Rydberg C Z gate in a three-level ladder-type atomic system. By tuning the temporal shapes of Gaussian or segmented pulses, the populations on the intermediate excited states are shown to be suppressed within the symmetric gate operation protocol, which leads to a C Z gate with a high Bell fidelity up to . These optimized pulses are robust to thermal fluctuations and the excitation field variations. Our results promise a high-fidelity and fast gate operation under amenable and controllable experimental parameters, which goes beyond the adiabatic operation regime under a finite blockade strength.

Discrete dynamics of light in an anti-parity-time symmetric photonic lattice in atomic vapors.

We demonstrate the realization of an anti-parity-time (PT)-symmetric photonic lattice in a coherent three-level Λ-type 85Rb atomic system both experimentally and theoretically. Such an instantaneously reconfigurable anti-PT-symmetric photonic lattice is "written" by two one-dimensional coupling fields, which are arranged alternately along the x direction and can modulate the refractive index of the atomic vapor in a spatially periodical manner via controllable atomic coherence. By properly adjusting the relevant atomic parameters, the phase shift between two adjacent lattice channels occurs in the constructed non-Hermitian photonic system. Such a readily reconfigurable anti-PT-symmetric photonic lattice may open the door for demonstrating the discrete characteristics of the optical waves in periodic anti-PT-symmetric photonic systems.

Storing quantum information in a generalised Dicke model via a simple rotation

A method for storing quantum information is presented for three-level atomic systems interacting dipolarly with a single radiation field. The method involves performing simple local SU(2) rotations on the Hamiltonian. Under equal detuning, these transformations decouple one of the atomic levels from the electromagnetic field for the Λ- and V-configurations, yielding two effective two-level systems (qubits) plus an isolated atomic level; this allows for the exchange of information between the qubits. This rotation preserves the quantum phase diagram of the system. The method could possibly be used as a means to manipulate quantum information, such as storage and retrieval, or communication via a transmission line.

Theoretical analysis of the resonance fluorescence correlation spectrum of three-level multi-mer 85Rb atomic system

In a vapor cell, [Formula: see text] is the average velocity of the moving atoms. When [Formula: see text], the in-homogeneous broadening of the atomic spectral lines is important when taking into account thermal Doppler broadening. We also discover that the narrowing mechanism for inter-atomic with different components has more influence on the Doppler line-shape. Thus, the spectral line broadening of two-level and three-level multi-mer [Formula: see text] atom is not only influenced by the in-homogeneous Doppler broadening, but also affected by the Dicke narrowing effect. The fluorescence spectrum affords a good possibility for a detailed study of Dicke narrowing effect and thermal Doppler broadening effect. We analyze the influence of multi-mer [Formula: see text] atomic system component on resonance fluorescence spectrum (RFS). Based on the quantum regression theorem, we develop a method and derive a general analytical expression for the two-dimensional (2D) fluorescence correlation spectrum of three-level [Formula: see text] atomic system.

Quantum state engineering in a three-level system with periodical Gaussian pulses

In this paper, we propose a scheme to achieve selective population transfer in a Λ-type three-level atomic system with a train of periodical Gaussian pulses. Based on temporal constructive quantum interference between the sequential transitions and subsequent coherent accumulations, the selective population transfer can be achieved with the pulse train, without satisfying the requirement of two-photon resonance condition. It can be understood as a result of the formation of a comb-like structure of the pulse train spectrum in time domain. Numerical simulations demonstrate that the scheme is robust against the wave-form deformation of single pulse while sensitive to the pulse train repetition period. Due to the Gaussian waveform of the laser field been readily implemented in experiments, the scheme holds great practicality for quantum state engineering in quantum information processing.

Tunable atom lithography scheme with high resolution in atomic system

We theoretically propose a scheme that utilizes the excited state of a Λ-type three-level atom system for atom lithography. A standing-wave coupling field and a probe field provide localized probability distribution of the excited atoms. Unlike the previous studies in atom localization, we focus on splitting the single-peak structure localized on the node of the standing-wave field to a double-peak structure. The shift distance of double-peak related to the parameters of external laser fields is investigated. The period of lithography pattern could reach λ/4, while the resolution of lithography is promising to be smaller than 0.02λ by adjusting system parameters. This scheme can be extended to form a two-dimensional pattern for lithography.

Light gap bullets in defocusing media with optical lattices

Searching for three-dimensional spatiotemporal solitons (also known as light/optical bullets) has recently attracted keen theoretical and experimental interests in nonlinear physics. Currently, optical lattices of diverse kinds have been introduced to the stabilization of light bullets, while the investigation for the light bullets of gap type – nonlinear localized modes within the finite gap of the underlying linear Bloch spectrum – is lacking. Herein, we address the formation and stabilization properties of such light gap bullets in periodic media with defocusing nonlinearity, theoretically and in numerical ways. The periodic media are based on two-dimensional periodic standing waves created in a coherent three-level atomic system which is driven to the regime of electromagnetically induced transparency, which in principle can also be replaced by photonic crystals in optics or optical lattices in ground-state ultracold atoms system. The temporal dispersion term is tuned to normal (positive) group velocity dispersion so that to launch the light gap bullets under self-repulsive nonlinearity; two types of such light gap bullets constructed as three-dimensional gap solitons and vortices with topological charge m=1 within the first finite gap are reported and found to be robustly stable in the existence domains. On account of the light bullets were previously limited to the semi-infinite gap of periodic media and continuous nonlinear physical systems, the light gap bullets reported here thus supplement the missing type of three-dimensional spatiotemporal localized modes in periodic media which exhibit finite band gaps.

Generation and Controllability of High-Dimensional Rogue Waves in an Electromagnetically Induced Transparent Medium

We propose a scheme to generate and control high-dimensional rogue waves in a coherent three-level Λ-type atomic system via electromagnetically induced transparency (EIT). Under EIT conditions, the probe field envelopes obey the non-integrable nonlinear Schrödinger equations (NLSE) with or without the external potential, which result from the stark (Zeeman) effect contributed by an electric (magnetic) field. By adjusting the amplitude and width of the initial pulse, we can generate the high-dimensional rogue waves and obtain the phase-transition curves of high-dimensional rogue waves. In the system, the far-detuned electric field, the random weak magnetic field, and the Gauss weak magnetic field are not conducive to the excitation of high-dimensional rogue waves. The results not only provide a theoretical basis for the experimental realization or prevention of the high-dimensional rogue waves, but also prove the possibility of generating and controlling the rogue waves in other high-dimensional non-integrable systems.