Resonance Radiation Pressure Research Articles

Transverse laser cooling of ions in a storage ring

We propose a method for a direct transverse laser cooling of ions in a storage ring and we discuss its application to 7Li + and 24Mg + ions studied in present storage rings. The key idea consists in the use of a broad-band laser, which, impinging transversely on the ion beam to be cooled, causes phase-space compression through resonance radiation pressure. Our technique, by allowing simultaneous resonant excitation of almost all ions regardless of their velocity, compensates for the short laser-ion interaction time and gives a very large capture range.

Vapor drift induced by resonance radiation pressure.

The resonance-radiation-pressure effect induced by a broadband long-cavity dye laser has been observed on sodium vapor confined in a capillary cell. The diffusion of the vapor has been studied as a function of laser intensity and vapor density, and the induced drift velocity has been measured. The time evolution of the vapor density is in agreement with the theoretical model under the hypothesis of optimized laser-vapor coupling. The drift velocity and the diffusion coefficient are shown instead to be larger than predicted, indicating an incomplete thermalization of the atoms at the cell walls.

Focusing of an Atomic Beam and Imaging of Atomic Sources by Means of a Laser Lens Based on Resonance-radiation Pressure

Abstract We propose and realize a laser lens capable of focusing an atomic beam by means of spontaneous-resonance radiation pressure. The focal length, resolution and aberrations of the laser lens are derived. An image from two atomic-beam sources has been obtained and the influence of chromatic aberration investigated.

Proposal for optically cooling atoms to temperatures of the order of 10^−6 K

We propose a technique for cooling optically trapped atoms to microkelvin temperatures, and lower, by using the dipole force of resonance-radiation pressure.

Cooling atoms by means of laser radiation pressure

The present state of research on the cooling of atomic ensembles by means of laser radiation pressure is discussed. First the basic theory of resonance radiation pressure is reviewed. The effect of recoil on the drift and fluctuations of the momentum of an atom interacting with resonance radiation is examined. There is an analysis of the forces acting on an atom in some simple light fields: a traveling plane wave, a Gaussian beam, and counterpropagating Gaussian beams. The review then focuses on the monochromatization of atoms by resonance radiation pressure and related methods for laser cooling of atoms. The roles played by the radiation pressure force and by momentum diffusion in shaping the narrow velocity distributions of the ensemble of atoms are analyzed. The lowest temperature obtainable in the radiation cooling of atoms is estimated. The basic experimental methods for laser cooling of atomic beams are described. Problems of the three-dimensional cooling of atomic ensembles and problems of localizing cold atoms in light fields, steady-state magnetic fields, and electrostatic fields are discussed. The review concludes with a discussion of some applications of cold atoms in high-precision spectroscopy, frequency standards, and atomic physics.

Three-dimensional viscous confinement and cooling of atoms by resonance radiation pressure.

We report the viscous confinement and cooling of neutral sodium atoms in three dimensions via the radiation pressure of counterpropagating laser beams. These atoms have a density of about \ensuremath{\sim}${10}^{6}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ and a temperature of \ensuremath{\sim}240 \ensuremath{\mu}K corresponding to a rms velocity of \ensuremath{\sim}60 cm/sec. This temperature is approximately the quantum limit for this atomic transition. The decay time for half the atoms to escape a \ensuremath{\sim}0.2${\mathrm{cm}}^{3}$ confinement volume is \ensuremath{\sim}0.1 sec.

Resonance-radiation pressure on atoms in symmetrical light fields

The radiation force acting on a two-level atom in an axisymmetric field of two counterpropagating light beams and a centrosymmetric field of six light beams propagating in the directions +/-x, +/-y, and +/-z has been considered. It is shown that, for radiative cooling of atoms by the light pressure force, the gradient force creates a potential well, the depth of which does not exceed the energy linewidth of resonant atomic transition. It is concluded that stable confinement of cold atoms in symmetrical light fields is impossible.

On the resonance light pressure

An expression for the resonance radiation pressure is found in the framework of the Weisskopf-Wigner theory. It is shown, that at saturation its value is twice that of the phenomenological theory.

Theory of resonance-radiation pressure

A general theory of the motion of a two-level atom in a resonant or near-resonant electromagnetic wave of arbitrary amplitude and phase, including effects of radiative relaxation due to interaction with the quantized vacuum field, is developed from first principles. Particular emphasis is placed on the effects of quantum-mechanical fluctuations of the radiation force and on the associated diffusion of atomic momentum due to spontaneous and induced absorption and emission processes. Analytic results and numerical examples are presented for (1) the lower bound on the temperature achievable by radiation cooling in a standing wave tuned below resonance, (2) the heating rate in a strong resonant standing wave, (3) the maximum confinement time for an atom in a Gaussian radiation trap, (4) the deflection and spreading of an atomic beam transversely illuminated by a strong resonant running wave, and (5) the transverse cooling of an atomic beam by a strong running wave tuned below resonance.

Experimental observation of the influence of the quantum fluctuations of resonance-radiation pressure: erratum

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text J. E. Bjorkholm, R. R. Freeman, A. Ashkin, and D. B. Pearson, "Experimental observation of the influence of the quantum fluctuations of resonance-radiation pressure: erratum," Opt. Lett. 5, 210-210 (1980) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Experimental observation of the influence of the quantum fluctuations of resonance-radiation pressure

We experimentally demonstrate that quantum fluctuations of the photon–atom interaction have a limiting influence on the focusing of neutral atomic beams by the dipole resonance-radiation pressure of a superimposed and co-propagating cw laser beam.

Anomalous resonance-radiation pressure on an inverted atomic transition

We point out that the radiation force acting force acting on an atom due to resonant interaction with a plane traveling electromagnetic wave is opposite to the direction of propagation of the wave when there is a population inversion on the resonant transition. The effect can be used as a test for population inversion in an atomic-beam experiment.

Focusing and defocusing of neutral atomic beams using resonance-radiation pressure

We demonstrate strong focusing and defocusing of a sodium atomic beam using the transverse resonance-radiation pressure of a superimposed cw dye laser beam tuned near the atomic resonance. Focal spot diameters of about 60 μm and a 30-fold increase of the on-axis atomic beam intensity have been obtained. For defocusing, the on-axis intensity can be reduced to less than 10−2 of its original value.

Transverse resonance radiation pressure on atomic beams and possible applications

Transverse resonance radiation pressure on atomic beams and possible applications

Cooling and trapping of atoms by resonance radiation pressure

The combined use of trapping and cooling laser beams for optical trapping and cooling of neutral atoms by the forces of resonance radiation pressure is examined. Calculations show that atoms can be held in traps as deep as 10(-4) eV at temperatures of ~10(-3) K, close to the minimum set by quantum fluctuations. Spatial confinement of atoms to a region a fraction of a wavelength in length should be possible.

Observation of Focusing of Neutral Atoms by the Dipole Forces of Resonance-Radiation Pressure

For sodium atoms in an atomic beam, we demonstrate focusing, defocusing, and steering caused by the transverse dipole forces exerted by the radial intensity gradient of a superimposed and co-propagating resonant cw light beam. Dipole radiation-pressure forces differ from the forces due to spontaneous emission and are needed to achieve optical traps for neutral atoms.

Manifestation of the resonance radiation pressure in a gas

The influence of the radiation pressure effect on the behavior of two-level gas in a field of a traveling quasi-resonance electromagnetic wave has been studied. The peak formation in the distribution function in a collisionless gas and the gas cooling in a collisional gas are shown.

Trapping of Atoms by Resonance Radiation Pressure

A method of stably trapping, cooling, and manipulating atoms on a continuous-wave basis is proposed using resonance radiation pressure forces. Use of highly focused laser beams and atomic beam injection should give a very deep trap for confining single atoms or gases at temperatures \ensuremath{\sim} ${10}^{\ensuremath{-}6}$ \ifmmode^\circ\else\textdegree\fi{}K. An analysis of the saturation properties of radiation pressure forces is given.

Observation of resonance radiation pressure on an atomic vapor

We have used the resonance radiation pressure from 40 mW of cw dye laser light propagating axially down a tube filled with sodium vapor to increase the sodium pressure (density) up to 50% over a length of 20 cm. The magnitude of the effect agrees well with measurements of the absorbed power. These observations were made with the laser tuned to the low-frequency side of the sodium D2 resonance line; for tuning to the high-frequency side, an additional unexplained effect leading to density decreases was observed.

Atomic-Beam Deflection by Resonance-Radiation Pressure

It is proposed to use the saturated value of the radiation pressure force on neutral atoms to produce a constant central force field to deflect atoms in circular orbits and make a high-resolution velocity analyzer. This is useful for studying the interaction of atoms with high-intensity monochromatic light, and to separate, velocity analyze, or trap neutral atoms of specific isotopic species or hyperfine level.