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Theoretical Issues Involving Traps for Neutral Spin-Polarized Atoms.

William C. Stwalley

Published Nov 15, 1984• 0 citations
OpenAlex

Abstract

The purpose of this project was to theoretically study and design a laser trap for neutral atoms. At low atomic densities, such a trap could be used to address a number of fundamental questions, e.g., the interaction of an individual atom with an electromagnetic field, collision dynamics, recombination. In particular, after examining a variety of laser-magnet trap concepts, we studied the feasibility and limitations of a 'corner cube' laser trap for potassium atoms based on a near-resonant CW TEM sub 01 ('doughnut mode') alexandrite laser beam with cooling provided by He4 atoms at approx. 1.5 K and designed initial experiments.

Related papers

A laser trap for neutral atoms

William C. Stwalley

This project constructed and studied a laser trap for neutral atoms, initially potassium (K). At low densities, such a trap could be used to address a number of fundamental questions, e.g. the interaction of an individual atom with an electromagnetic field, collision dynamics and recombination. The feasibility and limitations of a purely laser trap concept, a corner cube trap , for trapping neutral K atoms are studied. The confinement of the atoms in the two dimensions perpendicular to the laser is provided in the cavity of a newly constructed high power alexandrite laser operating in the (doughnut mode) tuned slightly to the blue side of the resonance line of the K atom. By reflecting the laser back on itself with two mirrors, one caps the ends of the cylindrical trap, resulting in a slightly weaker end plug. Examined are various loss mechanism for the trapped atoms. In particular, K atoms are lost to the trap if they are multiphoton ionized, if they are heated by absorption and emission of many photons, if they simply have much higher energy than the vast majority of other atoms at 1.5 K, or if they recombine with He to form KHe (or KHe2, etc).

NASA STI/Recon Technical Report N•Nov 1, 1985•0 citations

Progress toward an alexandrite laser trap for potassium atoms

K.-H. Yang, X.-Z. Zeng, W. C. Stwalley

A detailed description of a corner-cube laser trap concept inside the cavity of a cw alexandrite laser operating in the TEM 01 * mode and using 4He cooling (at temperature ≲ 1.5 K) for trapping neutral potassium atoms is given in a recent paper.1 We report recent progress made toward the implementation of this trap concept: in optimization of the design of the laser cavity, in the understanding of the thermal lensing effects in the alexandrite laser, and in the status of the cryogenic apparatus.

International Laser Science Conference•Jan 1, 1986•0 citations

Laser trap concept for cold potassium atoms

William C. Stwalley, Shawn P. Heneghan, John T. Bahns +1 more

We present our study on the feasibility and limitations of a purely laser trap concept, a corner cube trap, for trapping neutral K atoms. The confinement of the atoms in the two dimensions perpendicular to the laser will be provided in the cavity of a high power alexandrite laser operating in the cw TEM01*, mode (doughnut mode) tuned slightly to the blue side of the resonance line of the K atom. By reflecting the TEM01*, laser back on itself with two mirrors, one caps the ends of the cylindrical trap, resulting in a slightly weaker end plug. This trap concept employs not laser cooling, but rather counterstreaming 4He atoms which are cooled to ≲ 1.5 K, to drastically cool the K atoms to thermal energies well below the trap depth (expected to be ~10 K). We have also examined various loss mechanisms for the trapped atoms. In particular, K atoms can be lost to the trap if they are multiphoton ionized, if they are heated by absorption and emission of many photons (recoil or diffusional heating), if they simply have much higher energy than the vast majority of other atoms at 1.5 K, or if they form KHe (or KHe2, etc.). Results from these investigations will be discussed, suggesting crude lifetimes for trapped atoms of the order of 1 s.

Annual Meeting Optical Society of America•Jan 1, 1985•0 citations

Examination of effects of TEM01/emph> -mode laser radiation in the trapping of neutral potassium atoms

Kuo‐Ho Yang, William C. Stwalley, Shawn P. Heneghan +3 more

We present our study on the feasibility and limitations of a purely one-laser trap concept, a ``corner cube trap,'' for trapping neutral K atoms. The confinement of the atoms in the two dimensions perpendicular to the laser will be provided in the cavity of a high-power alexandrite laser operating in the cw ${\mathrm{TEM}}_{01}^{\mathrm{*}}$ mode (``doughnut mode'') tuned slightly to the blue side of the resonance line of the K atom. By reflecting the ${\mathrm{TEM}}_{01}^{\mathrm{*}}$ laser back on itself with two mirrors, one ``caps'' the ends of the cylindrical trap, resulting in a slightly weaker end plug. This trap concept employs not laser cooling, but rather counterstreaming $^{4}\mathrm{He}$ atoms which are cooled to \ensuremath{\lesssim}1.5 K, to drastically cool the K atoms to thermal energies well below the trap depth (expected to be \ensuremath{\sim}10 K). We have also examined various loss mechanisms for the trapped atoms. In particular, K atoms can be lost to the trap if they are multiphoton ionized, if they are heated by absorption and emission of many photons (``recoil'' or ``diffusional'' heating), if they simply have much higher energy than the vast majority of other atoms at 1.5 K, or if they form KHe (or ${\mathrm{KHe}}_{2}$, etc.). Results from these investigations suggest crude lifetimes for trapped atoms of the order of 1 sec.

Physical Review A•Oct 1, 1986•9 citations

Electromagnetic Trapping of Neutral Atoms

H. Metcalf, William D. Phillips

Electromagnetic trapping of neutral atoms is a new branch of applied physics that has potential for use in very many areas, including metrology and high-resolution precision spectroscopy. It has the possibility of leading toward the spectroscopic ideal of an isolated atom at rest, available for interaction with electromagnetic field probes. We present an introduction to trapping in both dc magnetic fields and optical fields (laser beams). The basic ideas and fundamental limitations are discussed and the first successful experiments are reviewed.

Metrologia•Jan 1, 1986•11 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
The purpose of this project was to theoretically study and design a laser trap for neutral atoms. At low atomic densities, such a trap could be used to address a number of fundamental questions, e.g., the interaction of an individual atom with an electromagnetic field, collision dynamics, recombination. In particular, after examining a variety of laser-magnet trap concepts, we studied the feasibility and limitations of a 'corner cube' laser trap for potassium atoms based on a near-resonant CW TEM sub 01 ('doughnut mode') alexandrite laser beam with cooling provided by He4 atoms at approx. 1.5 K and designed initial experiments.
This project constructed and studied a laser trap for neutral atoms, initially potassium (K). At low densities, such a trap could be used to address a number of fundamental questions, e.g. the interaction of an individual atom with an electromagnetic field, collision dynamics and recombination. The feasibility and limitations of a purely laser trap concept, a corner cube trap , for trapping neutral K atoms are studied. The confinement of the atoms in the two dimensions perpendicular to the laser is provided in the cavity of a newly constructed high power alexandrite laser operating in the (doughnut mode) tuned slightly to the blue side of the resonance line of the K atom. By reflecting the laser back on itself with two mirrors, one caps the ends of the cylindrical trap, resulting in a slightly weaker end plug. Examined are various loss mechanism for the trapped atoms. In particular, K atoms are lost to the trap if they are multiphoton ionized, if they are heated by absorption and emission of many photons, if they simply have much higher energy than the vast majority of other atoms at 1.5 K, or if they recombine with He to form KHe (or KHe2, etc).
A detailed description of a corner-cube laser trap concept inside the cavity of a cw alexandrite laser operating in the TEM 01 * mode and using 4He cooling (at temperature ≲ 1.5 K) for trapping neutral potassium atoms is given in a recent paper.1 We report recent progress made toward the implementation of this trap concept: in optimization of the design of the laser cavity, in the understanding of the thermal lensing effects in the alexandrite laser, and in the status of the cryogenic apparatus.
We present our study on the feasibility and limitations of a purely laser trap concept, a corner cube trap, for trapping neutral K atoms. The confinement of the atoms in the two dimensions perpendicular to the laser will be provided in the cavity of a high power alexandrite laser operating in the cw TEM01*, mode (doughnut mode) tuned slightly to the blue side of the resonance line of the K atom. By reflecting the TEM01*, laser back on itself with two mirrors, one caps the ends of the cylindrical trap, resulting in a slightly weaker end plug. This trap concept employs not laser cooling, but rather counterstreaming 4He atoms which are cooled to ≲ 1.5 K, to drastically cool the K atoms to thermal energies well below the trap depth (expected to be ~10 K). We have also examined various loss mechanisms for the trapped atoms. In particular, K atoms can be lost to the trap if they are multiphoton ionized, if they are heated by absorption and emission of many photons (recoil or diffusional heating), if they simply have much higher energy than the vast majority of other atoms at 1.5 K, or if they form KHe (or KHe2, etc.). Results from these investigations will be discussed, suggesting crude lifetimes for trapped atoms of the order of 1 s.
We present our study on the feasibility and limitations of a purely one-laser trap concept, a ``corner cube trap,'' for trapping neutral K atoms. The confinement of the atoms in the two dimensions perpendicular to the laser will be provided in the cavity of a high-power alexandrite laser operating in the cw TEM01∗{\mathrm{TEM}}_{01}^{\mathrm{*}}TEM01∗​ mode (``doughnut mode'') tuned slightly to the blue side of the resonance line of the K atom. By reflecting the TEM01∗{\mathrm{TEM}}_{01}^{\mathrm{*}}TEM01∗​ laser back on itself with two mirrors, one ``caps'' the ends of the cylindrical trap, resulting in a slightly weaker end plug. This trap concept employs not laser cooling, but rather counterstreaming 4He^{4}\mathrm{He}4He atoms which are cooled to \ensuremath{\lesssim}1.5 K, to drastically cool the K atoms to thermal energies well below the trap depth (expected to be \ensuremath{\sim}10 K). We have also examined various loss mechanisms for the trapped atoms. In particular, K atoms can be lost to the trap if they are multiphoton ionized, if they are heated by absorption and emission of many photons (``recoil'' or ``diffusional'' heating), if they simply have much higher energy than the vast majority of other atoms at 1.5 K, or if they form KHe (or KHe2{\mathrm{KHe}}_{2}KHe2​, etc.). Results from these investigations suggest crude lifetimes for trapped atoms of the order of 1 sec.
Electromagnetic trapping of neutral atoms is a new branch of applied physics that has potential for use in very many areas, including metrology and high-resolution precision spectroscopy. It has the possibility of leading toward the spectroscopic ideal of an isolated atom at rest, available for interaction with electromagnetic field probes. We present an introduction to trapping in both dc magnetic fields and optical fields (laser beams). The basic ideas and fundamental limitations are discussed and the first successful experiments are reviewed.