Arbitrary Detuning Research Articles

Stimulated magneto-optics with different detunings for plasma local diagnostics

The polarization plane stimulated rotation angle of a probe signal in an intense laser field in plasma is calculated for arbitrary detunings of intense and weak laser waves compared with the resonant transition frequency of the medium. Estimates of the residual gas local density in a cesium plasma have been found based on the Faraday, Cotton–Mouton effects and on the effect of stimulated rotation of the polarization plane of the probe signal in an intense laser field. It is shown that the rotation in the medium has a complex structure consisting of the sum of only the influence of the magnetic field, only the influence of the intense laser field and the interfering part of the magnetic and intense laser fields.

Gaussian-wave-packet model for single-photon generation based on cavity quantum electrodynamics under adiabatic and nonadiabatic conditions

For single-photon generation based on cavity quantum electrodynamics, we investigate a practical model assuming a Gaussian wavepacket. This model makes it possible to comprehensively analyze the temporal dynamics of an atom-cavity system with both adiabatic and nonadiabatic conditions using analytical expressions. These results enable us to clarify the relationship between pulse width and maximum success probability, over the full range of coupling regimes, for arbitrary detunings. We demonstrate how to achieve a high success probability while keeping a short pulse width by optimizing the cavity transmittance parameter. Our formulations provide a practical tool for efficient single-photon generation in a wide variety of experimental platforms.

Optical theorem for light scattering from a linear atomic chain

The radiation pattern of light scattered from a chain of atoms having $J=0$ ground states and $J=1$ excited states is calculated in the weak driving field approximation. It is shown that, in general, for arbitrary orientation of the driving field to the chain axis, it is not possible to treat the atoms in a two-level approximation owing to cooperative effects. In the limit of large detuning, however, all cooperative decay effects can be neglected in calculating the scattered spectrum. Nevertheless, even in this limit, in order to ensure conservation of energy, it is still necessary to include cooperative decay when calculating the energy lost by the driving field. For arbitrary detunings, conservation of energy can be expressed in the form of a generalized optical theorem.

Nonreciprocal conventional photon blockade in driven dissipative atom-cavity.

In this Letter, we propose a scheme to achieve a nonreciprocal conventional photon blockade in a nonlinear device consisting of an atom and spinning cavity by manipulating the detuning between the atom and the cavity. We show that the single-photon blockade can be generated by driving the spinning resonator from one side, while photon-induced tunneling is driven by the other side with the same driving strength. This nonreciprocal conventional photon blockade effect originates from the Fizeau-Sagnac drag, which leads to different splitting of the resonance frequencies for the counter-circulating modes. We give four optimal solutions for Fizeau-Sagnac shifts to generate a nonreciprocal conventional photon blockade with the arbitrary detunings between atom and cavity.

Analytical Solutions of the Second-Order Correlation Function in Resonance Fluorescence for Two-level Systems

We present analytical solutions for the second-order correlation function [g(2)(τ)] for light scattered from a two-level atom driven by laser light with arbitrary detuning and the Rabi frequency. By solving the optical Bloch equations for a two-level atom, we obtain analytical solutions for the populations that are subsequently used for calculating g(2)(τ). We also obtain g(2)(τ) for special cases, such as zero detuning or weak laser intensity, directly from the general analytical solutions for g(2)(τ).

Mollow spectrum influenced by collisional fluctuations described by a stochastic model of collisions

In this paper, we consider the influence of collisional fluctuations on optical phenomena. The fluctuations are taken into account by a simple shift of the constant detuning, involved in a set of optical Bloch equations by collision frequency noise in which this noise is modelled by a two-step random telegraph signal. Following that, the stochastic Bloch equations can be solved analytically in an exact way. As an example, we consider in detail the Mollow spectrum of resonance fluorescence for the case of an arbitrary detuning of the laser frequency, where velocity of the emitters simply has a deterministic value or is distributed with the Maxwell–Boltzmann density in which volume of the buffer gas is arbitrary.

Optomechanical entanglement under pulse drive.

We report a study of optomechanical entanglement under the drive of one or a series of laser pulses with arbitrary detuning and different pulse shapes. Because of the non-existence of system steady state under pulsed driving field, we adopt a different approach from the standard treatment to optomechanical entanglement. The situation of the entanglement evolution in high temperature is also discussed.

Continuously tunable modulation scheme for precision control of optical cavities with variable detuning.

We present a scheme for locking optical cavities with arbitrary detuning by many linewidths from resonance using an electro-optic modulator that can provide arbitrary ratios of amplitude-to-phase modulation. We demonstrate our scheme on a Fabry-Perot cavity, and show that a well-behaved linear error signal can be obtained by demodulating the reflected light from a cavity that is detuned by several linewidths.

A stochastic model of the influence of buffer gas collisions on Mollow spectra

In this paper we consider the influence of collisional fluctuations on the Mollow spectra of resonance fluorescence (RF). The fluctuations are taken into account by a simple shift of the constant detuning, involved in a set of optical Bloch equations by collision frequency noise which is modelled by a two-step random telegraph signal (RTS). We consider in detail the Mollow spectra for RF in the case of an arbitrary detuning of the laser frequency, where the emitter is a member of a statistical ensemble in thermodynamic equilibrium with the buffer gas at temperature $T$ which is treated as a colored environment, and velocity $v$ is distributed with the Maxwell-Boltzmann density.

Space-time descriptions of quantum fields interacting with optical cavities

The purpose of this paper is to compare two unitary, deterministic approaches to the study of the interaction of quantized fields with atomic systems in optical cavities. In particular it is shown that the ``modes of the universe'' approach, in which each mode has both an intracavity and an outside part, is formally equivalent, in an appropriate limit, to the better known ``input-output'' formalism in its unitary (i.e., Hermitian-Hamiltonian based) form; the latter may be called a ``quasimode'' theory, since it treats the field inside the cavity as a separate degree of freedom. Differences that arise between the two approaches for numerical calculations involving a finite set of discrete modes are also pointed out. The formalism is illustrated with an in-depth discussion of the explicit solution for a single-photon pulse, of arbitrary shape and detuning, incident on a cavity containing a two-level atom.

The n-level, n − 1-mode Jaynes–Cummings model: spectrum and eigenvectors

We explicitly find eigenvectors and eigenvalues of the general n-level, n − 1-mode Jaynes–Cummings model in Λ-configuration possessing arbitrary detuning parameters Δi, and arbitrary interaction strengths gi, . In the case of equal interaction strengths gi = gj, , we compare the obtained answers with those obtained by the algebraic Bethe ansatz method (Skrypnyk 2008 J. Phys. A: Math. Theor. 41 475202; 2009 J. Math. Phys. 50 103523).

Asynchronous optical sampling with arbitrary detuning between laser repetition rates

A method of asynchronous optical sampling based on free-running lasers with no requirement on the repetition rates is presented. The method is based on the a posteriori determination of the delay between each pair of pulses. A resolution better than 400 fs over 13 ns total delay scan is demonstrated. In addition to the advantages of conventional asynchronous sampling techniques, this method allows a straightforward implementation on already-existing laser systems using a fiber-based setup and an appropriate acquisition procedure.

Exactly solvable three-level quantum dissipative systems via bosonization of fermion gas-impurity models

We study the relationship between one-dimensional fermion gas-impurity models and quantum dissipative systems, via the method of constructive bosonization and unitary transformation. Starting from an anisotropic Coqblin–Schrieffer model, a new, exactly solvable, three-level quantum dissipative system is derived as a generalization of the standard spin- spin-boson model. The new system has two environmental oscillator baths with ohmic coupling, and admits arbitrary detuning between the three levels. All tunnelling matrix elements are equal, up to one complex phase which is itself a function of the longitudinal and transverse couplings in the integrable limit. Our work underlines the importance of re-examining the detailed structure of fermion-gas impurity models and spin chains, in the light of connections to models for quantum dissipative systems.

Non-Markovian dynamics of a biased qubit coupled to a structured bath

A new analytical approach, beyond the rotating wave approximation, based on unitarytransformations and the non-Markovian master equation for the density operator,is applied to treat the biased spin–boson model with a Lorentzian structuredbath for arbitrary detunings at zero temperature. Compared to zero bias, we findthat the non-equilibrium dynamics demonstrates two more damping oscillationfrequencies and one additional relaxation frequency for non-zero bias. Analyticalexpressions for the non-Markovian dynamics and the corresponding spectrum, thelocalized–delocalized transition point, the coherent–incoherent transition point, theanalytical ground energy, the renormalized tunneling factor and the susceptibility aredetermined. The sum rule and the Shiba relation are checked in the coherent regime.

Spontaneous recoil effects of optical pumping on trapped atoms

The recoil effects of spontaneous photon emissions during optical pumping of a trapped three-level atom are exactly calculated. Without resort to the Lamb-Dicke approximation, and considering arbitrary detuning and saturation of the pump laser, the density of recoil shifts in phase space is derived. It is shown that this density is not of Gaussian shape, and that it becomes isotropic in phase space only for a branching ratio corresponding to fluorescence scattering but unfavorable for optical pumping. The dependence of its anisotropy on the laser saturation is discussed in the resonant case, and the mapping of moments of the atom's center-of-mass motion due to the pumping is presented. Moreover, it is shown how optimum parameters for protecting the center-of-mass quantum state from pump-induced disturbance depend on the specific property to be protected.

BCS-BEC crossover of a quasi-two-dimensional Fermi gas: The significance of dressed molecules

We study the crossover of a quasi-two-dimensional Fermi gas trapped in the radial plane from the Bardeen-Cooper-Schrieffer (BCS) regime to the Bose-Einstein condensation (BEC) regime by crossing a wide Feshbach resonance. We consider two effective two-dimensional Hamiltonians within the mean-field level, and calculate the zero-temperature cloud size and number density distribution. For a model 1 Hamiltonian with renormalized atom-atom interaction, we observe a constant cloud size for arbitrary detunings. For a model 2 Hamiltonian with renormalized interactions between atoms and dressed molecules, the cloud size deceases from the BCS to BEC side, which is consistent with the picture of BCS-BEC crossover. This qualitative discrepancy between the two models indicates that the inclusion of dressed molecules is essential for a mean-field description of quasi-two-dimensional Fermi systems, especially on the BEC side of the Feshbach resonance.

Dynamics of a qubit coupled to a broadened harmonic mode at finite detuning

We study the dynamics of a symmetric two-level system strongly coupled to a broadened harmonic mode. Upon mapping the problem on to a spin–boson model with peaked spectral density, we show how analytic solutions can be obtained, at arbitrary detuning and finite temperatures, in the case of large Q-factors of the oscillator. One, two or more dominating oscillation frequencies of the two-level particle can be observed as a consequence of the entanglement with the oscillator. Our approximated analytical solution agrees well with numerical predictions obtained within the non-interacting blip approximation.

Superradiance and multiple scattering of photons in atomic gases

We study the influence of cooperative effects such as superradiance and subradiance on the scattering properties of dilute atomic gases. We show that cooperative effects lead to an effective potential between two atoms that decays as $1∕r$. In the case of superradiance, this potential is attractive for close enough atoms and can be interpreted as a coherent mesoscopic effect. We consider a model of multiple scattering of a photon among superradiant pairs and calculate the elastic mean free path and the group velocity. We study first the case of a scalar wave which allows us to obtain and to understand basic features of cooperative effects and multiple scattering. We then turn to the general problem of a vector wave. In both cases, we obtain qualitatively similar results and derive, for the case of a scalar wave, analytic expressions for the elastic mean free path and for the group velocity for an arbitrary detuning (near resonance).

Vibronic Rabi resonances in harmonic and hard-wall ion traps for arbitrary laser intensity and detuning

We investigate laser-driven vibronic transitions of a single two-level atomic ion in harmonic and hard-wall traps. In the Lamb-Dicke regime, for tuned or detuned lasers with respect to the internal frequency of the ion, and weak or strong laser intensities, the vibronic transitions occur at well-isolated Rabi resonances, where the detuning-adapted Rabi frequency coincides with the transition frequency between vibrational modes. These vibronic resonances are characterized as avoided crossings of the dressed levels (eigenvalues of the full Hamiltonian). Their peculiarities due to symmetry constraints and trapping potential are also examined.

Ground-state instabilities and entanglement in the spin-boson model

Ground-state instabilities of the spin-boson model is studied in this work. The existence of sequential ground-state instabilities is shown analytically for arbitrary detuning in the two-spin system. In this model, extra discontinuities of concurrence (entanglement measure) are found in the finite system, which do not appear in the on-resonant model. The above results remain intact by including extra boson modes. Moreover, by including extra modes, it is found that ground-state entanglement can be obtained and enhanced even in the weak coupling regime.