arXiv subjects

M. D. Havey

Publications and source records attributed to M. D. Havey.

34 records · Page 2Linked to original sources

arXiv2013

Multiple light scattering on the F = 1 - F' = 0 transition in a cold and high density 87Rb vapor

We report an experimental study of near resonance light scattering on the $F = 1 \rightarrow F' = 0$ component of the $D_2$ line in atomic $^{87}Rb$. Experiments are performed on spatially bi-Gaussian ultracold gas samples having peak densities ranging from about $5 \cdot 10^{12} - 5 \cdot 10^{13}$ atoms/cm$^{3}$ and for a range of resonance saturation parameters and detunings from atomic resonance. Time resolution of the scattered light intensity reveals dynamics of multiple light scattering, optical pumping, and saturation effects. The experimental results in steady-state are compared qualitatively with theoretical models of the light scattering process. The steady-state line shape of the excitation spectrum is in good qualitative agreement with these models.

physics.atom-ph↗

arXiv2013

Near-resonance Light Scattering from a High-density, Ultracold Atomic $^{87}$Rb Gas

We report a combined experimental and theoretical investigation of near resonance light scattering from a high-density and ultracold atomic $^{87}$Rb gas. The atomic sample, having a peak density $\sim 5\cdot10^{13}$ atoms/cm$^{3}$, temperature $\sim$ 65 $μ$K and initially prepared in the F = 1 lower energy $^{87}$Rb hyperfine component, is optically pumped to the higher energy F = 2 hyperfine level. Measurements are made of the transient hyperfine pumping process and of the time evolution of scattering of near resonance probe radiation on the $F = 2 \rightarrow F' = 3$ transition. Features of the density, detuning, and temporal dependence of the signals are attributed to the high density and consequent large optical depth of the samples.

quant-ph↗

arXiv2012

A scaling law for light scattering from dense and cold atomic ensembles

We calculate the differential cross section of polarized light scattering from a cold and dense atomic ensemble. The regularities in the transformation of the cross section when increasing the size of the atomic ensemble are analyzed numerically. We show that for typical experimental conditions, an approximate scaling law can be obtained. Very good agreement is found in a comparison with experimental data on the size dependence of a dense and cold cloud of 87$Rb atoms.

quant-ph↗

arXiv2011

Quantum hologram of macroscopically entangled light via the mechanism of diffuse light storage

In the present paper we consider a quantum memory scheme for light diffusely propagating through a spatially disordered atomic gas. The diffuse trapping of the signal light pulse can be naturally integrated with the mechanism of stimulated Raman conversion into a long-lived spin coherence. Then the quantum state of the light can be mapped onto the disordered atomic spin subsystem and can be stored in it for a relatively long time. The proposed memory scheme can be applicable for storage of the macroscopic analog of the $Ψ^{(-)}$ Bell state and the prepared entangled atomic state performs its quantum hologram, which suggests the possibility of further quantum information processing.

quant-ph↗

arXiv2011

Dispersion of the dielectric permittivity of dense and ultracold atomic gases

On the basis of general theoretical results developed previously in JETP 112, 246 (2011) we analyze the atomic polarization created by weak monochromatic light in an optically thick, dense and cold atomic ensemble. We show that the amplitude of the polarization averaged over a uniform random atomic distribution decreases exponentially beyond the boundary regions. The phase of this polarization increases linearly with increasing penetration into the medium. On these grounds, we determine numerically the wavelength of the light in the dense atomic medium, its extinction coefficient, and the complex refractive index and dielectric constant of the medium. The dispersion of the permittivity is investigated for different atomic densities. It is shown that for dense clouds, the real part of the permittivity is negative in some spectral domains.

quant-ph↗

arXiv2011

Coherent control of diffuse light dynamics in an ultracold atomic gas

We show that coherent multiple light scattering, or diffuse light propagation, in a disordered atomic medium, prepared at ultra-low temperatures, can be be effectively delayed in the presence of a strong control field initiating a stimulated Raman process. On a relatively short time scale, when the atomic system can preserve its configuration and effects of atomic motion can be ignored, the scattered signal pulse, diffusely propagating via multiple coherent scattering through the medium, can be stored in the spin subsystem through its stimulated Raman-type conversion into spin coherence. We demonstrate how this mechanism, potentially interesting for developing quantum memories, would work for the example of a coherent light pulse propagating through an alkali-metal atomic vapor under typical conditions attainable in experiments with ultracold atoms.

quant-ph↗

arXiv2011

Coherent backscattering under conditions of electromagnetically induced transparency

We consider the influence of a resonant control field on weak localization of light in ultracold atomic ensembles. Both steady-state and pulsed light excitation are considered. We show that the presence of a control field essentially changes the type of interference effects which occur under conditions of multiple scattering. For example, for some scattering polarization channels the presence of a control field can cause destructive interference through which the enhancement factor, normally considered to be greater than one, becomes less than one.

quant-ph↗

arXiv2011

Microscopic Theory of Scattering of Weak Electromagnetic Radiation by a Dense Ensemble of Ultracold Atoms

Based on the developed quantum microscopic theory, the interaction of weak electromagnetic radiation with dense ultracold atomic clouds is described in detail. The differential and total cooperative scattering cross sections are calculated for monochromatic radiation as particular examples of application of the general theory. The angular, spectral, and polarization properties of scattered light are determined. The dependence of these quantities on the sample size and concentration of atoms is studied and the influence of collective effects is analyzed.

quant-ph↗

arXiv2010

Light trapping in high-density ultracold atomic gases for quantum memory applications

High-density and ultracold atomic gases have emerged as promising media for storage of individual photons for quantum memory applications. In this paper we provide an overview of our theoretical and experimental efforts in this direction, with particular attention paid to manipulation of light storage (a) through complex recurrent optical scattering processes in very high density gases (b) by an external control field in a characteristic electromagnetically induced transparency configuration.

quant-ph↗

arXiv2009

Imaging-based Parametric Resonance in an Optical Dipole Atom Trap

We report sensitive detection of parametric resonances in a high-density sample of ultracold $^{87}Rb$ atoms confined to a far-off-resonance optical dipole trap. Fluorescence imaging of the expanded ultracold atom cloud after a period of parametric excitation shows significant modification of the atomic spatial distribution and has high sensitivity compared with traditional measurements of parametrically-driven trap loss. Using this approach, a significant shift of the parametric resonance frequency is observed, and attributed to the anharmonic shape of the dipole trap potential.

quant-ph↗

arXiv2009

Magnetic field imaging with atomic Rb vapor

We demonstrate the possibility of dynamic imaging of magnetic fields using electromagnetically induced transparency in an atomic gas. As an experimental demonstration we employ an atomic Rb gas confined in a glass cell to image the transverse magnetic field created by a long straight wire. In this arrangement, which clearly reveals the essential effect, the field of view is about 2 x 2 mm^2 and the field detection uncertainty is 0.14 mG per 10 um x 10 um image pixel.

quant-ph↗

arXiv2008

Light scattering and localization in an ultracold and dense atomic system

The quantum optical response of high density ultracold atomic systems is critical to a wide range of fundamentally and technically important physical processes. These include quantum image storage, optically based quantum repeaters and ultracold molecule formation. We present here a microscopic analysis of the light scattering on such a system, and we compare it with a corresponding description based on macroscopic Maxwell theory. Results are discussed in the context of the spectral resonance structure, time-dependent response, and the light localization problem.

quant-ph↗

arXiv2006

Diffuse light scattering dynamics under conditions of electromagnetically induced transparency

We show that, under conditions of electromagnetically induced transparency (EIT), a significant portion of the incident probe pulse can be transferred into Rayleigh and Raman scattering channels. The light scattered into the Rayleigh channel emerges from the sample with an EIT time delay. We show that a proper description of the probe light propagation in the sample should include, in the diffusion dynamics, a spin polariton generated by the two-photon EIT process. The results have important implications for studies of weak light localization, and for manipulation of single and few photon states in ultracold atomic gases.

physics.atom-ph↗

arXiv2004

Antilocalization in Coherent Backscattering of Light in a Multi-Resonance Atomic System

Theoretical prediction of antilocalization of light in ultracold atomic gas samples, in the weak localization regime, is reported. Calculations and Monte-Carlo simulations show that, for selected spectral ranges in the vicinity of atomic 85Rb hyperfine transitions, quantum coherence in optical transitions through nondegenerate hyperfine levels in multiple light scattering generates destructive interference in otherwise reciprocal scattering paths. This effect leads to enhancement factors less than unity in a coherent backscattering geometry, and suggests the possibility of enhanced diffusion of light in ultracold atomic vapors.

quant-ph↗

arXiv2003

Precision study of 6p 2Pj - 8s 2S1/2 relative transition matrix elements in atomic Cs

A combined experimental and theoretical study of transition matrix elements of the 6p 2Pj - 8s 2S1/2 transition in atomic Cs is reported. Measurements of the polarization-dependent two-photon excitation spectrum associated with the transition were made in an approximately 200 cm-1 range on the low frequency side of the 6s 2S1/2 - 6p 2P3/2 resonance. The measurements depend parametrically on the relative transition matrix elements, but also are sensitive to far-off-resonance 6s 2S1/2 - np 2Pj - 8s 2S1/2 transitions. In the past, this dependence has yielded a generalized sum rule, the value of which is dependent on sums of relative two-photon transition matrix elements. In the present case, best available determinations from other experiments are combined with theoretical matrix elements to extract the ratio of transition matrix elements for the 6p 2Pj - 8s 2S1/2 (j = 1/2,3/2) transition. The resulting experimental value of 1.423(2) is in excellent agreement with the theoretical value, calculated using a relativistic all-order method, of 1.425(2).

physics.atom-ph↗

arXiv2003

Spectral Dependence of Coherent Backscattering of Light in a Narrow-Resonance Atomic System

We report a combined theoretical and experimental study of the spectral and polarization dependence of near resonant radiation coherently backscattered from an ultracold gas of 85Rb atoms. Measurements in an approximately 6 MHz range about the 5s^{2}S_{1/2}- 5p^{2}P_{3/2}, F=3 - F'=4 hyperfine transition are compared with simulations based on a realistic model of the experimental atomic density distribution. In the simulations, the influence of heating of the atoms in the vapor, magnetization of the vapor, finite spectral bandwidth, and other nonresonant hyperfine transitions are considered. Good agreement is found between the simulations and measurements.

quant-ph↗