Intensity Of Control Field Research Articles

Properties of a Broadband Gaussian Pulse Propagating Through a Λ-type Atomic Medium at Room Temperature

Abstract In our study, we conduct a comprehensive theoretical analysis on the propagation behavior of a Gaussian pulse through a four-level Λ-type Rubidium atomic medium under room temperature conditions. Our investigation uncovers the presence of two distinct wavepackets within the medium’s transmission signal. The primary wavepacket, linked to electromagnetically induced transparency transmission, serves as the central signal in the study. Characterized by its optical beat signal utilized for fast microwave strength detection, this wavepacket demonstrates notable features such as pronounced normal dispersion and decreased group velocity. Additionally, the emergence of the Sommerfeld-Brillouin precursor as the second wavepacket further enriches our understanding of pulse dynamics in the medium. Our simulation findings reveal the potential for the optical precursor to play a dominant role in the transmission signal with the adopted methodology. Furthermore, we identify that experimental parameters like atomic density, vapor cell length, and control field intensity play crucial roles in modulating the time delay of the primary signal and the amplitude of the optical precursor.

Controllable optical effects in Landau-quantized graphene

This paper investigates the manipulation and control of optical properties in a Y-configured four-level Landau-Quantized Graphene system. Through a comprehensive analysis of the density matrix elements, we explore the influence of various system parameters, including control field intensities, detunings, and decay rates, on the optical response of the graphene sample. Our findings unveil compelling phenomena such as optical transparency, sub- and superluminal light propagation, and the emergence of multiple absorption peaks and transparency windows. Specifically, we examine the impact of decay rates on the absorption characteristics of graphene, revealing that higher decay rates diminish the effectiveness of Electromagnetically Induced Transparency (EIT) and slow light in the system. Furthermore, by systematically varying system parameters, we demonstrate the controllability of achieving either single or double EIT through manipulation of control field intensities and detunings. These results open promising avenues for applications in optical communications and quantum information processing, where precise control over graphene's optical properties is critical.

Dynamics of induced optical torque via optical vortex light

This paper investigates the dynamics of induced torque in Nitrogen-Vacancy (NV) centers interacting with two weak optical vortex beams as well as a strong control field, exploring the impact of different system parameters such as control field intensity, detuning, magnetic field, and vortex beam strength. We find a dispersive torque behavior, indicating the sensitivity of NV centers to control parameters. Magnetic field induces level splitting, leading to a transformative effect on torque, with notable enhancements observed at specific intensities. Additionally, non-resonant torque is explored, demonstrating the controllability of torque peaks through magnetic field manipulation. Unequal strengths of vortex beams is found to yield substantial enhancements in torque. These results provide crucial insights into the induced torque dynamics in NV centers, presenting opportunities for optimized torque-based applications in quantum systems.

Inducing torque on molecular magnets via Laguerre Gaussian beams

This theoretical study delves into the induction of torque by light beams carrying orbital angular momentum on single-molecule magnets (SMMs). The investigation explores the impact of decay rates, detunings, and control field intensities on the generation of light-induced torque and the resulting current flow in a ring formation. The results highlight the crucial role of the control field, showcasing its efficacy as a tool to manipulate and amplify torque at different frequencies. Detuning is identified as a critical parameter influencing the shift, slope, and emergence of multiple peaks in the torque profile. The interplay between detuning, control field intensity, and decay rates introduces a control mechanism for fine-tuning torque at distinct probe frequencies. These findings underscore the potential applications of the control field and detuning as robust tools for tailored manipulation of torque in SMMs, paving the way for advancements in controlled current flow dynamics with ring structures.

Coherent control of light-induced torque on four-level tripod atom systems

This paper investigates the manipulation of induced torque on a four-level tripod atom system through the interaction with two vortex probe beams featuring spatial inhomogeneity, along with a non-vortex control beam. The study explores both the linear and nonlinear regimes of torque induction. In the linear regime, where the intensity of the vortex beams is weaker than that of the control field, effective control over the induced torque is demonstrated by adjusting parameters such as magnetic field strength, control field intensity, detuning, and dephasing terms between relevant atomic levels. The analysis highlights the significant contribution of the Zeeman shift-induced magnetic field, which enhances the torque and exhibits a distinct sharp peak. Furthermore, higher-order contributions to the induced torque are discussed as the intensity of the probe fields approaches that of the control field, resulting in further enhancement of the induced torque. These findings offer opportunities for precise control over the rotational motion of atoms within the system, with potential applications in precision measurement, quantum information processing, and quantum control.

Исследование когерентного пленения населенности и динамического эффекта Штарка в ансамблях NV-центров в алмазе при комнатной температуре в микроволновом диапазоне

We study coherent population trapping and AC Stark effect using microwave transitions between the sublevels of the ground state of the NV-center. Sublevels with different projections of the nuclear spin of the nitrogen atom are used to implement the Lambda-scheme. Dependence of the characteristics of the coherent population trapping dip on the control field frequency and intensity is studied. Various schemes for observing the AC Stark effect are considered.

Study of coherent population trapping and AC Stark effect in ensembles of NV-centers in diamond at room temperature in microwave range

We study coherent population trapping and AC Stark effect using microwave transitions between the sublevels of the ground state of the NV-center. Sublevels with different projections of the nuclear spin of the nitrogen atom are used to implement the -scheme. Dependence of the characteristics of the coherent population trapping dip on the control field frequency and intensity is studied. Various schemes for observing the AC Stark effect are considered. Keywords: NV-center, coherent population trapping, AC Stark.

Tunable second-order sideband effects in hybrid optomechanical cavity assisted with a Bose–Einstein condensate

We theoretically investigated a second-order optomechanical-induced transparency (OMIT) process of a hybrid optomechanical system (COMS), which a Bose–Einstein condensate (BEC) in the presence of atom–atom interaction trapped inside a cavity with a moving end mirror. The advantage of this hybrid COMS over a bare COMS is that the frequency of the second mode is controlled by the s-wave scattering interaction. Based on the traditional linearization approximation, we derive analytical solutions for the output transmission intensity of the probe field and the dimensionless amplitude of the second-order sideband (SS). The numerical results show that the transmission intensity of the probe field and the dimensionless amplitude of the SS can be controlled by the s-wave scattering frequency. Furthermore, the control field intensities, the effective detuning, the effective coupling strength of the cavity field with the Bogoliubov mode are used to control the transmission intensity of the probe field and the dimensionless amplitude of the SS.

Shape-preserving atomic pulse amplifier

Propagation of a weak probe pulse through a Λ system in a resonant gain configuration is investigated. We employ the control field intensity that permits the amplification of probe pulse during propagation, without instability at two photon resonance. Posterior to amplification, a broadened probe pulse is obtained, which retains its initial pulse shape and travels at the speed of light in vacuum without experiencing any delay, absorption, and dispersion. The salient feature of this technique lies in the fact that in addition to preserving the initial pulse shape, it also ensures stable pulse propagation after amplification. It also works for arbitrary probe pulse shapes.

Effective control and switching of optical multistability in a three-level V-type atomic system

We theoretically analyze the behavior of single optical bistability (OB), double OB, and tristability (OT) in a three-level V-type atomic system confined in a unidirectional optical ring cavity. The physics behind the emergence of various bistable and tristable states, and switching from the absorptive to the dispersive characteristics, are explored. The role of probe- and control-field detunings on the input-output characteristics is probed. Further, it is found that the switching between various bistable phenomena is defined by the ratio between the absolute peak values of the parameters describing dispersion and absorption, respectively. This ratio sets a criterion for obtaining absorptive OB, OT, double OB, and dispersive OB. The role of control-field intensity and detuning as well as the cooperation parameter on the input-output characteristics are explored. Finally, a scheme is discussed to control the width of the middle branch of double OB and OT as well as single OB.

Optically tunable grating in a V+Ξ configuration involving a Rydberg state

A novel tunable all-optical grating is realized experimentally in a V+Ξ configuration coherent rubidium thermal vapor. This new energy level structure employs a Rydberg level as the uppermost level and contains two typical electromagnetically induced transparency energy level configurations with the same probe field. Compared with the traditional V-type three-level grating, a significant improvement of the diffraction efficiency of this novel grating was observed. Its improvement was then also demonstrated experimentally by the transition spectrum and theoretically by a comprehensive simulation. The diffraction efficiency gain introduced by the control laser field was tuned with several experimental parameters, such as the atomic density and the control field intensity. And the maximum enhancement rate of first-order diffraction efficiency is proved to be as high as 30%. Such a novel all-optical tunable grating promises to be the new driving force in the advancement of all-optical communications and information technology.

Proposal of nonlinear measurement of tunneling in quantum wells with Fano interference

An enhanced absorption spectrum by Fano interference is proposed to measure the tunneling between a discrete state and a continuum in asymmetric quantum wells (QWs). Interestingly, the asymmetry of the enhanced absorption spectrum is sensitive to tunneling strength, which can be used to measure the tunneling in QWs. Further study shows that the asymmetry of a nonlinear absorption spectrum is greater than that of a linear absorption spectrum, indicating better probe sensitivity. The simulation results show that the probe sensitivity based on nonlinear absorption is approximately 10 times larger than that of linear absorption. In addition, the effects of control-field intensity and detuning on probe sensitivity are evaluated.

Microwave induced phase grating in molecular magnets via cross phase modulation

In this paper, we focus on the forming microwave induced phase grating (MIPG) in a crystal of molecular magnets. Firstly, we calculate the energy split of molecular magnet in the present of dc magnetic filed, and the results show that the frequencies dependence of the dc magnetic field are in the microwave frequency range. Secondly, the molecular magnet is subject two strong control magnetic fields (standing wave field and pump magnetic field). When a weak probe magnetic field with the frequency in the microwave range enters the crystal, the two control magnetic fields will modify the transmission and reflection properties of weak magnetic field. The system achieves high transmissivity and a big phase excursion for the weak probe magnetic field and form a microwave phase grating. Under proper parameters condition, the first-order diffraction efficiency of the microwave phase grating reaches 31%, which is close to an ideal sinusoidal phase grating. And the diffraction efficiency of the grating can be adjusted efficiently by tuning the control field intensity, interaction length L and the single photon detuning. Thirdly, we also discuss the effect of Dopper effect on the microwave phase grating.

Optical bistability and multistability induced by quantum coherence in diamond germanium-vacancy color centers.

Optical bistability (OB) and optical multistability (OM) behaviors are investigated theoretically in a four-level N-type diamond germanium-vacancy (GeV) color center scheme immersed in a unidirectional ring cavity based on electromagnetically induced transparency (EIT). It is found that OB behavior is very sensitive to the system parameters, such as the detunings of probe and coupling fields and the intensities of coupling fields as well as the density of GeV centers, and the thresholds of OB can be controlled via changing these parameters. In addition, we can switch OB to OM by adjusting the intensity of control field and the density of GeV centers or vice versa. Our results may provide some guidance for an all-optical switching, optical communications, and optical logic devices in a solid-state system.

Electromagnetic control and improvement of nonclassicality in a strongly coupled single-atom cavity-QED system

We present a study of the electromagnetic control of nonclassicality of the outgoing light field in a single atom cavity QED system. By exploring the energy eigenvalues and eigenstates, we show that the eigenstates are similar to the Jaynes-Cummings ladder of eigenstates and can be optically controlled by an external control field. Tuning the control field frequency to the one photon resonance, we show the superbunching behavior in the outgoing light field can be observed at the frequency of one photon resonance. We also show that there exists a magic control field intensity at which two photon blockade phenomenon can be significantly improved. In particular, it is possible to adjust the nonclassicality of the outgoing field from quantum to classical by varying the control field intensity. The work presented here provides an optical method to control statistical features of the outgoing field and can be useful for the nonclassical light generation, quantum gate operation and exotic quantum state generation.

High-order sideband generation in a two-cavity optomechanical system with modulated photon-hopping interaction

The high-order sideband generation in a two-cavity optomechanical system is discussed, where photon hopping between the two cavity modes is modulated sinusoidally. We show that the high-order sideband generation can be induced originating from two processes: the parametric frequency conversion between the photon–photon interactions and the nonlinear optomechanical interactions between the photon–phonon interactions. Both the modulation amplitude and frequency of photon hopping between the two cavities have flexible manipulation on the high-order sideband generation at the low pump power level. With the modulation amplitude varying, we are able to obtain a robust comb-type spectral structure and a weak spectral structure, which can be amplified by tuning the modulation frequency. Selective generation of particular sidebands may also been achieved via transforming the modulation frequency when the parametric conversion process is dominant. Moreover, the dependence of the high-order sideband generation on other important parameters is also discussed in detail, including the cavities linewidthes, the frequency detuning of the two input laser fields and the intensity of control field. These results may provide further insights into the understanding of the high-order sideband generation, and find applications in optical frequency converters and optical frequency combs.

Photon drag enhancement by a slow-light moving medium via electromagnetically-induced transparency amplification

Recently, a considerable enhancement has been observed in the celebrated Fresnel–Fizeau light drag by innovative experimental and theoretical approaches because of its fundamental and practical interest in the emerging technology of quantum optics and photonics. We present a semiclassical density matrix approach on the demonstration of light drag in a slow-light moving medium comprising five-level single tripod atomic configuration. To accomplish this, we introduce Kerr-type nonlinearity that leads to electromagnetically-induced transparency amplification under resonance conditions. By switching ON Kerr-type nonlinearity effect, we observe a prominent transparency window in probe field's absorption spectrum whose width and amplitude can be controlled further by the intensity of Kerr field and control field. The incorporation of Kerr field also switches light propagation from superluminal to subluminal domain. We predict a significant enhancement both in the lateral and the rotary photon drag owing to drag of light linear polarization state subjected to translation and rotation of the host medium, respectively. Consistent with earlier results, light drag considerably depends on both transverse and angular velocity of the host medium. In regime of subluminal propagation, light polarization state drags along the medium motion while in the superluminal propagation region it drags opposite to the medium motion.

Optical switching, bistability and pulse propagation in five-level quantum schemes

We explore the effect of a control field on the optical properties of a probe field in five-level inverted Y-type atom–light coupling schemes. While in the absence of the control field, it is discovered that the system is opaque for the probe field. When the control field is turned on, the medium switches to transparency for the probe field. In addition to analytical solutions, numerical results are given in terms of a Gaussian intensity profile of the probe field to elucidate such optical switching. Considering all orders of the probe field, we also study the absorption features of the atomic medium in a unidirectional ring cavity, giving rise to optical bistability. It is shown that in this model, the OB threshold can be controlled by both the control field intensity as well as probe field detuning.

Electric field effect on the impurity-related electromagnetically induced transparency in a quantum disk under non-resonant, intense laser radiation

By considering a three-level ladder-type system under electromagnetically induced transparency, the absorption and dispersion of the probe field in a GaAs disk-like quantum dot under simultaneous action of the electric field and non-resonant, intense laser radiation are investigated. We found that some characteristics such as the width of the transmission window and group velocity can be efficiently manipulated by tuning the control field intensity, non-resonant radiation amplitude and electric field strength. Our results may be relevant for future investigations of the optical process in semiconductor quantum structures and for the technological applications in solid- state optoelectronics.

-symmetry in Rydberg atoms

We propose a scheme to realize parity-time ()-symmetry in an ensemble of strongly interacting Rydberg atoms, which act as superatoms due to the dipole blockade mechanism. We show that Rydberg-dressed 87Rb atoms in a four-level inverted Y-type configuration is highly efficient to generate the refractive index for a probe field, with a symmetric (antisymmetric) profile spatially in the corresponding real (imaginary) part. Comparing with earlier investigations, the present scheme provides a versatile platform to control the system from -symmetry to non--symmetry via different external parameters, i.e., coupling field detuning, probe field intensity and control field intensity.