Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physics Today

Laser Beam Focus Forms Optical Trap for Neutral Atoms

Bertram M. Schwarzschild

Published Sep 1, 1986• 2 citations
Publisher

Abstract

The first color photographs ever to grace the pages of Physical Review Letters show us the fluorescent glow from some 500 sodium atoms caught in the first successfully demonstrated optical trap for neutral atoms. The 21 July Letter by Steven Chu, John Bjorkholm, Arthur Ashkin and Alex Cable at Bell Labs, reports that this tiny “optical dipole” trap, formed at the focus of a single laser beam, was able to hold onto an ultracold, high-density accumulation of atoms for several seconds and manipulate them in space. In recent days the group has been able to hold a much larger collection of sodium atoms for a fraction of a minute with a newer optical-trap design.

DOI
10.1063/1.2815137

Related papers

Continuous stopping and trapping of neutral atoms

Vanderlei Salvador Bagnato, Gregory P. Lafyatis, Alexander G. Martin +2 more

We have continuously stopped thermal sodium atoms with laser light and loaded them into a 0.1-K deep superconducting magnetic trap. The trap is formed by a local minimum of the magnetic field produced by two superconducting coils and a radially confining octupole field. The atoms are slowed and stopped in two stages: The atoms are first slowed to ~200 m/s using a counterpropagating resonant laser beam and tapered magnetic field to compensate for the changing Doppler shift as the atoms are slowed.1 A second laser beam and tapered magnetic field, actually located within the trap, are used to stop the atoms in the trap. This continuous loading process has allowed us to accumulate up to 1 × 109 trapped atoms, and trapping times of several minutes have been achieved. Our trap has the feature of having a uniform magnetic field at its bottom, opening up the possibility of precision spectroscopy of the trapped atoms. The fluorescence from the trapped atoms has been studied, and they have been cooled to ~1 mK using 1-D optical molasses.

Annual Meeting Optical Society of America•Jan 1, 1987•0 citations

Experimental Observation of Optically Trapped Atoms

Steven Chu, John E. Bjorkholm, Arthur Ashkin +1 more

We report the first observation of optically trapped atoms. Sodium atoms cooled below ${10}^{\ensuremath{-}3}$ K in "optical molasses" are captured by a dipole-force optical trap created by a single, strongly focused, Gaussian laser beam tuned several hundred gigahertz below the ${D}_{1}$ resonance transition. We estimate that about 500 atoms are confined in a volume of about ${10}^{3}$ \ensuremath{\mu}${\mathrm{m}}^{3}$ at a density of ${10}^{11}$-${10}^{12}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. Trap lifetimes are limited by background pressure to several seconds. The observed trapping behavior is in good quantitative agreement with theoretical expectations.

Physical Review Letters•Jul 21, 1986•830 citations

Single atom dipole trap

Jürgen Volz, M. Weber, R. Reicold +3 more

In the experiment, single Rubidium-87 atoms are loaded out of a molasses of Doppler-cooled atoms into the focus of a Gaussian laser beam created by a single mode laser diode with a wavelength of 856 nm. A confocal microscope outside our vacuum chamber is used to focus the trapping beam to a minimal waist of 3.5 /spl mu/m (thus creating a trap depth of 1-2 mK) and to collect the fluorescence light from the center of the dipole trap. The collected fluorescence light is coupled into a single-mode optical fiber for spatial filtering, and the photons are detected with an avalanche photodiode. With this setup the overall detection efficiency of photons emitted from the trap region is about 0.2%. First experimental results show sub-Poissonian occupation statistics of the dipole trap: only single atoms are observed inside our trap, never two ore more. The measured 1/e lifetime of atoms inside the dipole trap in the presence of cooling light is about 1-2 seconds. To prove that we really observe single atoms inside the trap, a Hanbury-Brown-Twiss measurement of the fluorescence light from the trap will be shown. The trapping of single atoms inside our dipole trap marks the first step towards the investigation of the properties of an entangled atom photon state. Progress in preparing and analyzing single atoms in well defined hyperfine ground states will be reported.

European Quantum Electronics Conference (EQEC)•Jan 1, 2003•0 citations

Laser-cooling and electromagnetic trapping of neutral atoms

William D. Phillips, Alan L. Migdall, H. Metcalf

Until recently it has been impossible to confine and trap neutral atoms using electromagnetic fields. While many proposals for such traps exist, the small potential energy depth of the traps and the high kinetic energy of available atoms prevented trapping. We review various schemes for atom trapping, the advances in laser cooling of atomic beams which have now made trapping possible, and the successful magnetic trapping of cold sodium atoms.

AIP conference proceedings•Jan 1, 1986•6 citations

Continuous stopping and trapping of neutral atoms

Gregory P. Lafyatis, V. S. Baganato, Alexander G. Martin +2 more

We are now able to hold billions of laser cooled sodium atoms for minutes in a magnetic neutral trap. Physics experiments that might be done in this type of trap are outlined. The trap itself is described and results which characterize the loading and trapping of the atoms are presented. Finally, we report very recent work in which R. F. transitions between magnetic hyperfine levels have been driven.

AIP conference proceedings•Jan 1, 1988•3 citations

All-optical Bose-Einstein condensates

M. D. Barrett, J.A. Sauer, Michael Chapman

Summary form only given. Recently, we have created a Bose condensate of /sup 87/Rb atoms directly in an optical trap formed by tightly focused laser beams. Following initial loading from a laser cooled gas, evaporative cooling through the BEC transition is achieved by simply lowering the depth of the optical trap. Our success is due in part to a high initial phase space density realized in the loading of our optical dipole trap and in part to the tight confinement of the atoms that permits rapid evaporative cooling to the BEC transition in 2 s.

Quantum Electronics and Laser Science Conference•Jun 25, 2003•0 citations
The first color photographs ever to grace the pages of Physical Review Letters show us the fluorescent glow from some 500 sodium atoms caught in the first successfully demonstrated optical trap for neutral atoms. The 21 July Letter by Steven Chu, John Bjorkholm, Arthur Ashkin and Alex Cable at Bell Labs, reports that this tiny “optical dipole” trap, formed at the focus of a single laser beam, was able to hold onto an ultracold, high-density accumulation of atoms for several seconds and manipulate them in space. In recent days the group has been able to hold a much larger collection of sodium atoms for a fraction of a minute with a newer optical-trap design.
We have continuously stopped thermal sodium atoms with laser light and loaded them into a 0.1-K deep superconducting magnetic trap. The trap is formed by a local minimum of the magnetic field produced by two superconducting coils and a radially confining octupole field. The atoms are slowed and stopped in two stages: The atoms are first slowed to ~200 m/s using a counterpropagating resonant laser beam and tapered magnetic field to compensate for the changing Doppler shift as the atoms are slowed.1 A second laser beam and tapered magnetic field, actually located within the trap, are used to stop the atoms in the trap. This continuous loading process has allowed us to accumulate up to 1 × 109 trapped atoms, and trapping times of several minutes have been achieved. Our trap has the feature of having a uniform magnetic field at its bottom, opening up the possibility of precision spectroscopy of the trapped atoms. The fluorescence from the trapped atoms has been studied, and they have been cooled to ~1 mK using 1-D optical molasses.
We report the first observation of optically trapped atoms. Sodium atoms cooled below ${10}^{\ensuremath{-}3}$ K in "optical molasses" are captured by a dipole-force optical trap created by a single, strongly focused, Gaussian laser beam tuned several hundred gigahertz below the D1{D}_{1}D1​ resonance transition. We estimate that about 500 atoms are confined in a volume of about 103{10}^{3}103 \ensuremath{\mu}m3{\mathrm{m}}^{3}m3 at a density of 1011{10}^{11}1011-1012{10}^{12}1012 ${\mathrm{cm}}^{\ensuremath{-}3}$. Trap lifetimes are limited by background pressure to several seconds. The observed trapping behavior is in good quantitative agreement with theoretical expectations.
In the experiment, single Rubidium-87 atoms are loaded out of a molasses of Doppler-cooled atoms into the focus of a Gaussian laser beam created by a single mode laser diode with a wavelength of 856 nm. A confocal microscope outside our vacuum chamber is used to focus the trapping beam to a minimal waist of 3.5 /spl mu/m (thus creating a trap depth of 1-2 mK) and to collect the fluorescence light from the center of the dipole trap. The collected fluorescence light is coupled into a single-mode optical fiber for spatial filtering, and the photons are detected with an avalanche photodiode. With this setup the overall detection efficiency of photons emitted from the trap region is about 0.2%. First experimental results show sub-Poissonian occupation statistics of the dipole trap: only single atoms are observed inside our trap, never two ore more. The measured 1/e lifetime of atoms inside the dipole trap in the presence of cooling light is about 1-2 seconds. To prove that we really observe single atoms inside the trap, a Hanbury-Brown-Twiss measurement of the fluorescence light from the trap will be shown. The trapping of single atoms inside our dipole trap marks the first step towards the investigation of the properties of an entangled atom photon state. Progress in preparing and analyzing single atoms in well defined hyperfine ground states will be reported.
Summary form only given. Recently, we have created a Bose condensate of /sup 87/Rb atoms directly in an optical trap formed by tightly focused laser beams. Following initial loading from a laser cooled gas, evaporative cooling through the BEC transition is achieved by simply lowering the depth of the optical trap. Our success is due in part to a high initial phase space density realized in the loading of our optical dipole trap and in part to the tight confinement of the atoms that permits rapid evaporative cooling to the BEC transition in 2 s.