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Manipulating Spin-Torque Dynamics in Atomic Media Using Kerr Field with Two-Wave Interference

Muhammad Tariq, Abuzar Khan

Published Feb 13, 2024• 0 citations
Publisher

Abstract

Abstract In this article, Spin density and Torque of two interfering waves are controlled and manipulated by applying two interacting control fields in which one is the Kerr field with Rabi frequency Ω2 and a probe field using a four-level N-type atomic configuration of Rubidium-87 isotope. The spin density of light can be controlled coherently in the atomic medium by electromagnetically induced transparency (EIT). When the strong interacting control fields and the weak probe field are applied to the atomic medium, the Rubidium atoms become transparent to the probe field. It is due to the control fields that ”dress” the atoms, creating a new energy state that the weak probe field can interact with. As a result, the weak probe field can pass through the Rubidium atomic medium without being absorbed. Substantial variations can be seen in the electric SAM and Torque of two interfering waves with variations in the angle β between the two interfering waves, the Rabi frequencies of the control fields, the detuning of the probe field, and the phase difference δϕ between waves. By introducing these changes of parameters in the atomic medium, the spin density of two interfering waves can be made to rotate in a specific direction or at a specific rate. The parameters of control fields and probe field detuning play an essential role in the modification of electric SAM and electric spin vector field distribution of the probe field. The modified work of this manuscript is useful for Quantum computing, Optical communication, Quantum information processing.

DOI
10.21203/rs.3.rs-3950258/v1

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Abstract In this article, Spin density and Torque of two interfering waves are controlled and manipulated by applying two interacting control fields in which one is the Kerr field with Rabi frequency Ω2 and a probe field using a four-level N-type atomic configuration of Rubidium-87 isotope. The spin density of light can be controlled coherently in the atomic medium by electromagnetically induced transparency (EIT). When the strong interacting control fields and the weak probe field are applied to the atomic medium, the Rubidium atoms become transparent to the probe field. It is due to the control fields that ”dress” the atoms, creating a new energy state that the weak probe field can interact with. As a result, the weak probe field can pass through the Rubidium atomic medium without being absorbed. Substantial variations can be seen in the electric SAM and Torque of two interfering waves with variations in the angle β between the two interfering waves, the Rabi frequencies of the control fields, the detuning of the probe field, and the phase difference δϕ between waves. By introducing these changes of parameters in the atomic medium, the spin density of two interfering waves can be made to rotate in a specific direction or at a specific rate. The parameters of control fields and probe field detuning play an essential role in the modification of electric SAM and electric spin vector field distribution of the probe field. The modified work of this manuscript is useful for Quantum computing, Optical communication, Quantum information processing.
Abstract In this article, Spin density and Torque of two interfering waves are controlled and manipulated by applying two interacting control fields and a probe field using a four-level N-type atomic configuration of Rubidium-87 isotope. The spin density of light can be controlled coherently in the atomic medium by electromagnetically induced transparency (EIT). When the strong interacting control fields and the weak probe field are applied to the atomic medium, the Rubidium atoms become transparent to the probe field. It is due to the control fields that "dress" the atoms, creating a new energy state that the weak probe field can interact with. As a result, the weak probe field can pass through the Rubidium atomic medium without being absorbed. Substantial variations can be seen in the electric SAM and Torque of two interfering waves with variations in the angle β\betaβ between the two interfering waves, the Rabi frequencies of the control fields, the detuning of the probe field, and the phase difference δϕ\delta \phiδϕ between waves. By introducing these changes of parameters in the atomic medium, the spin density of two interfering waves can be made to rotate in a specific direction or at a specific rate. The parameters of control fields and probe field detuning play an essential role in the modification of electric SAM and electric spin vector field distribution of the probe field. The modified work of this manuscript is useful for Quantum computing, Optical communication, Quantum information processing. Key Words: Dynamical properties of light, Electric spin density, Two-wave interference, coherent control, Four-level N-type atomic configuration
Abstract This research investigates the intricate interplay between Gaussian beams and atomic media, introducing a novel approach by incorporating a Kerr field and spatially dependent refractive index. The study employs a Gaussian probe field as the primary interaction medium with the atomic ensemble, while simultaneously introducing two control fields. One of these control fields acts as a Kerr field, imparting a unique modulation on the propagation characteristics of the Gaussian beam. The key parameters under scrutiny encompass the probe field detuning (∆P /γ), as well as the Rabi frequencies and detunings of the control fields (Ω1,2/γ, ∆1,2/γ). Further exploration involves transforming one of the control fields into a Gaussian beam, resulting in the creation of a spatially dependent refractive index within the atomic medium. The investigation focuses on the spatial coordinates x/ω0 and y/ω0, where ω0 represents the Gaussian beam waist. This intricate configuration provides a unique platform for studying the manipulation and control of light propagation in atomic media. The research not only sheds light on fundamental interactions in quantum optics but also opens avenues for potential applications in quantum information processing and precision measurement. The outcomes of this study contribute valuable insights into the dynamics of Gaussian beams in complex atomic environments, with potential implications for quantum technology and communication.
In the last few decades, coherent light-atom interactions have opened unprecedented possibilities for the coherent control of atomic and optical quantum systems, paved the way for the practical realization of quantum information technologies, and allowed for the creation of novel quantum-enhanced sensors. This dissertation investigates the interaction of multiple near-resonant optical fields with hot rubidium atoms under the conditions of electromagnetically induced transparency. The main goal of the presented research is to address some fundamental challenges in using such systems for practical applications. The EIT effect relies on the strong coupling of an optical probe field and a collective long-lived ensemble of atomic spins by the means of a strong classical optical control field in a Lambda configuration. While optically-thick atomic vapor is necessary to achieve such a strong coupling regime, the increasing optical depth of the atomic ensemble also leads to the effective enhancement of other nonlinear light-atom interactions, such as the four-wave mixing effect. Here we discuss the possibility to control four-wave mixing in a three-level system without deteriorating the coherent properties of EIT by introducing an additional absorber resonant exclusively with the Stokes field. The exclusive detection of a weak probe field in the presence of a strong control field is a challenging experimental task, especially at the few-photon level. Many experiments employ polarization and/or frequency filtering to compete the task. We present an alternative filtering technique based on optical vortices for cases when the traditional methods are not sufficient or restrict the experimental arrangements. Finally, we demonstrate the possibility to manipulate the group velocity of a pulsed squeezed vacuum field by using the optical dispersion modification via Zeeman spin coherence in rubidium atoms. By changing the interaction condition, we demonstrate the switch between the ``slow'' and (for the first time) ``fast'' light regime. We also show that increased optical depth simultaneously leads to the enhancement of pulse advancement and the deterioration of squeezing fidelity in the output pulses.
We investigate the generation of optical torque in coherently prepared multi-level atomic media driven by a vector vortex beam composed of two counter-rotating components carrying opposite orbital angular momenta, +lℏ+l\hbar+lℏ and −lℏ-l\hbar−lℏ. We consider a three-level ΛΛΛ configuration and a four-level tripod configuration. Using a perturbative steady-state solution of the optical Bloch equations, we obtain analytical expressions for both linear and nonlinear contributions to the optical torque. The results show that the torque is strongly controlled by atomic coherence, including the initial population imbalance and the relative phase between the vortex components. Nonvanishing torque can arise even when the two components have equal amplitudes, due to coherence-induced asymmetry in the atomic response. In the tripod configuration, the presence of a strong control field leads to electromagnetically induced transparency, which suppresses the torque near resonance and shifts the dominant response to finite detunings. These results establish a route for controlling light-induced rotational dynamics in atomic media using vector vortex fields, with potential applications in coherent optical manipulation and angular-momentum-based control in quantum systems.
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.
This research investigates the intricate interplay between a Hermite-Gaussian (HG) weak probe field and a five-level tripod atomic medium, modulated by three laser fields. The atomic medium's refractive index is made spatially dependent by a Hermite-Gaussian beam of light and influenced further by a Kerr field and a control field. The study focuses on exploring the impact of key parameters on the propagation dynamics of the HG probe field. The primary parameters under scrutiny include the probe field detuning (ΔP/γ\Delta_P/\gammaΔP​/γ), Kerr, coherent pump, and control field characteristics such as Rabi frequencies and detunings (Ω1,2,3/γ\Omega_{1,2,3}/\gammaΩ1,2,3​/γ, Δ1,2,3/γ\Delta_{1,2,3}/\gammaΔ1,2,3​/γ), as well as spatial coordinates x/ω0x/\omega_0x/ω0​ and y/ω0y/\omega_0y/ω0​, where ω0\omega_0ω0​ denotes the Gaussian beam waist. Through systematic analysis, we elucidate the intricate effects of these parameters on the modulation of the HG probe field within the atomic medium. The study not only contributes to the fundamental understanding of light-matter interactions in complex atomic systems but also holds promise for potential applications in quantum information processing and communication. The results provide valuable insights into the control and manipulation of light beams in spatially varying media, paving the way for advancements in quantum optics and atomic physics.