The techniques of optical trapping and manipulation of neutral particles by lasers provide unique means to control the dynamics of small particles. These new experimental methods have played a revolutionary role in areas of the physical and biological sciences. This paper reviews the early developments in the field leading to the demonstration of cooling and trapping of neutral atoms in atomic physics and to the first use of optical tweezers traps in biology. Some further major achievements of these rapidly developing methods also are considered.

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Optical trapping and manipulation of neutral particles using lasers

Publisher Summary This chapter discusses optical dipole traps for neutral atoms Methods for storage and trapping of charged and neutral particles have very often served as the experimental key to great scientific advances, covering physics in the vast energy range from elementary particles to ultracold atomic quantum matter It describes the basic physics of dipole trapping in fardetuned light, the typical experimental techniques and procedures, and the different trap types currently available, along with their specific features In the experiments discussed, optical dipole traps have already shown great promise for a variety of different applications Of particular importance is the trapping of atoms in the absolute internal ground state, which cannot be trapped magnetically In this state, inelastic binary collisions are completely suppressed for energetic reasons In this respect, an ultracold cesium gas represents a particularly interesting situation, because Bose–Einstein condensation seems attainable only for the absolute ground state Therefore, an optical trap may be the only way to realize a quantum-degenerate gas of Cs atoms Further, optical dipole traps can be seen as storage devices at the low end of the presently explorable energy scale Future experiments exploiting the particular advantages of these traps can reveal interesting new phenomena

Optical Dipole Traps for Neutral Atoms

Reviews the history of optical trapping and manipulation of small-neutral particles, from the time of its origin in 1970 up to the present. As we shall see, the unique characteristics of this technique are having a major impact on the many subfields of physics, chemistry, and biology where small particles play a role.

History of optical trapping and manipulation of small-neutral particle, atoms, and molecules

Laser cooling and trapping of neutral atoms

We report that small particles with diameters of 1–27 μm have moved in the evanescent fields produced by a laser beam. The evanescent field in the experiment was produced in the near field of the surface of a high-refractive-index sapphire prism illuminated by a 1.06-μm YAG laser beam with an incident angle larger than the critical angle. Both polystyrene latex spheres and glass spheres bounced and ran along the surface of the prism when the laser beam was on. The maximum running speed obtained was approximately 20 μm/s. A micrograph of the running particles is shown with plots of the measured velocity versus the incident angle of the laser beam. Applications of this phenomenon are also discussed.

Movement of micrometer-sized particles in the evanescent field of a laser beam.

Quantum-state−selective mirror reflection of atoms by laser light

Gravitational laser trap for atoms with evanescent-wave cooling.

Laser guiding of atoms in a hollow optical fiber

A new type of gradient light trap is suggested for neutral atoms, based on the evanescent fields of two laser beams experiencing total internal reflection at a dielectric- vacuum interface A distinctive feature ofthe trap is that its bottom is close to the interface: at a distance of the order of the wavelength of light

https://iopscience.iop.org/article/10.1088/0953-4075/24/14/009/pdf

An atomic trap based on evanescent light waves

We report on the observation of a strong optical dipole force which is exerted on atoms in a bichromatic standing light wave as a result of nonlinear wave-mixing processes. This force can substantially exceed the upper limit of the spontaneous light force and, in contrast to the dipole force in monochromatic standing-wave fields, acts with constant sign on a macroscopic spatial scale.

Yu. B. Ovchinnikov

Papers

Quantum-state−selective mirror reflection of atoms by laser light

Gravitational laser trap for atoms with evanescent-wave cooling.

Laser guiding of atoms in a hollow optical fiber

An atomic trap based on evanescent light waves

Observation of a strong rectified dipole force in a bichromatic standing light wave.