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Quantum Electronics and Laser Science Conference

Permanent-magnet trap for cold atoms

Charles A. Sackett, J. J. Tollett, C. C. Bradley, Randall G. Hulet

Published May 22, 1995• 0 citations
OpenAlex

Abstract

We have constructed a permanent-magnet trap that provides a tightly confining potential useful for producing dense ultracold atomic vapors.1 This trap will be used to investigate quantum-statistical effects of 6Li and 7Li. Permanent magnets can produce field strengths and gradients comparable to those of superconducting-magnet traps but with reduced complexity and greater optical access. Our trap uses an arrangement of magnets in an Ioffe configuration,2 which features a nonzero magnetic-field minimum. Atoms are trapped about this minimum through the interaction of their total magnetic moment with the trap's magnetic field. The nonzero minimum prevents trap- loss-producing spin-flip (Majorana) transitions.

Related papers

Permanent magnet trap for cold atoms

J. J. Tollett, C. C. Bradley, Charles A. Sackett +1 more

We report the trapping of neutral atoms in a permanent magnet trap. Approximately 1\ifmmode\times\else\texttimes\fi{}${10}^{8}$ ground-state lithium atoms have been confined in a nonzero magnetic-field minimum produced by six permanent magnets in an Ioffe configuration. These atoms have a kinetic temperature of 1.1 mK and a peak density of approximately 3\ifmmode\times\else\texttimes\fi{}${10}^{9}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$. The trapped-atom lifetime is 240 s, limited by collisions with background gas. This trap provides an environment in which quantum-statistical effects, atomic collisions, and other ultralow-temperature phenomena can be studied.

Physical Review A•Jan 1, 1995•54 citations

a Permanent Magnet Trap for Cold Atoms

J. J. Tollett

Approximately$4\\times10\\sp8$ ground state lithium atoms have been confined in a non-zero magnetic field minimum produced by six permanent magnets in an Ioffe configuration. These atoms have a kinetic temperature of 1.1 mK and a peak density of $8\\times10\\sp9$ cm$\\sp{-3}$ The trapped atom lifetime is 240 seconds, limited by collisions with background gas. The tightly confining fields generated through the use of permanent magnets create a trap which is an excellent environment for the study of quantum statistical effects, atomic collisions, and other ultra-low temperature phenomena.

•Jan 1, 1995•0 citations

Permanent magnetic microtraps for ultracold atoms

Amir Mohammadi, Saeed Ghanbari, Aref Pariz

We propose and numerically study two permanent magnetic micro-structures for creating Ioffe-Pritchard microtraps. A bias magnetic field is used to vary the depth, trap frequencies and the minimum of each microtrap. After the Bose-Einstein condensation achievement, the bias magnetic field can be slowly removed to increase the trap barrier heights for more efficiently holding the Bose-Einstein condensates. Even without the external magnetic field, it is possible to hold ultracold atoms in the microtraps. These microtraps may also be useful for single atom experiments for quantum information processing due to their very high confinement.

arXiv:1007.2912•Jul 17, 2010•1 citation

Permanent magnetic lattices for ultracold atoms and quantum degenerate gases

Saeed Ghanbari, Tien D. Kieu, Andrei I. Sidorov +1 more

We propose the use of periodic arrays of permanent magnetic films for producing magnetic lattices of microtraps for confining, manipulating and controlling small clouds of ultracold atoms and quantum degenerate gases. Using analytical expressions and numerical calculations we show that periodic arrays of magnetic films can produce one-dimensional (1D) and two-dimensional (2D) magnetic lattices with non-zero potential minima, allowing ultracold atoms to be trapped without losses due to spin flips. In particular, we show that two crossed layers of periodic arrays of parallel rectangular magnets plus bias fields, or a single layer of periodic arrays of square-shaped magnets with three different thicknesses plus bias fields, can produce 2D magnetic lattices of microtraps having non-zero potential minima and controllable trap depth. For arrays with micron-scale periodicity, the magnetic microtraps can have very large trap depths ($\sim$0.5 mK for the realistic parameters chosen for the 2D lattice) and very tight confinement.

arXiv:cond-mat/0512371•Journal of Physics B Atomic Molecular and Optical Physics•Jan 18, 2006•74 citations

3D permanent magnetic lattices for ultracold atoms

Saeed Ghanbari

Abstract We introduce 3D permanent magnetic lattices for ultracold atoms which can be created by arbitrary number of 2D arrays of square permanent magnetic slabs plus a bias magnetic field. Instead of the square magnets, we can also use magnetic films with square holes. We find analytical expressions for the location of the nonzero magnetic field minima and physical quantities such as trap depths, absolute value of the magnetic field and curvatures as well as trap frequencies at each minimum. We show that most of them, including the trap depths, modulation depths, and trap frequencies can be controlled by the bias field. Accessible trap depths and trap frequencies in the permanent magnetic lattices are much higher compared to the optical lattices. Between the magnetic layers, the trap frequencies are higher compared to above the top layer (under the bottom layer). In principle, our method can be generalized to other 2D permanent magnetic lattices and we show how to transform a 2D lattice of a given geometry into 3D by using multiple layers of magnets.

Physica Scripta•Sep 15, 2023•1 citation

A class of 2D permanent magnetic lattices for ultracold atoms and BECs

Saeed Ghanbari, Tien D. Kieu, Bryan J. Dalton +2 more

We report on a class of permanent magnetic lattices for producing 2D arrays of magnetic microtraps with nonzero potential minima and variable barrier height for trapping and manipulating ultracold atoms and Bose Einstein condensates.

•Jan 1, 2005•0 citations
We have constructed a permanent-magnet trap that provides a tightly confining potential useful for producing dense ultracold atomic vapors.1 This trap will be used to investigate quantum-statistical effects of 6Li and 7Li. Permanent magnets can produce field strengths and gradients comparable to those of superconducting-magnet traps but with reduced complexity and greater optical access. Our trap uses an arrangement of magnets in an Ioffe configuration,2 which features a nonzero magnetic-field minimum. Atoms are trapped about this minimum through the interaction of their total magnetic moment with the trap's magnetic field. The nonzero minimum prevents trap- loss-producing spin-flip (Majorana) transitions.
We report the trapping of neutral atoms in a permanent magnet trap. Approximately 1\ifmmode\times\else\texttimes\fi{}108{10}^{8}108 ground-state lithium atoms have been confined in a nonzero magnetic-field minimum produced by six permanent magnets in an Ioffe configuration. These atoms have a kinetic temperature of 1.1 mK and a peak density of approximately 3\ifmmode\times\else\texttimes\fi{}109{10}^{9}109 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$. The trapped-atom lifetime is 240 s, limited by collisions with background gas. This trap provides an environment in which quantum-statistical effects, atomic collisions, and other ultralow-temperature phenomena can be studied.
Approximately4times10sp84\\times10\\sp84times10sp8 ground state lithium atoms have been confined in a non-zero magnetic field minimum produced by six permanent magnets in an Ioffe configuration. These atoms have a kinetic temperature of 1.1 mK and a peak density of 8times10sp98\\times10\\sp98times10sp9 cmsp−3\\sp{-3}sp−3 The trapped atom lifetime is 240 seconds, limited by collisions with background gas. The tightly confining fields generated through the use of permanent magnets create a trap which is an excellent environment for the study of quantum statistical effects, atomic collisions, and other ultra-low temperature phenomena.
We propose and numerically study two permanent magnetic micro-structures for creating Ioffe-Pritchard microtraps. A bias magnetic field is used to vary the depth, trap frequencies and the minimum of each microtrap. After the Bose-Einstein condensation achievement, the bias magnetic field can be slowly removed to increase the trap barrier heights for more efficiently holding the Bose-Einstein condensates. Even without the external magnetic field, it is possible to hold ultracold atoms in the microtraps. These microtraps may also be useful for single atom experiments for quantum information processing due to their very high confinement.
We propose the use of periodic arrays of permanent magnetic films for producing magnetic lattices of microtraps for confining, manipulating and controlling small clouds of ultracold atoms and quantum degenerate gases. Using analytical expressions and numerical calculations we show that periodic arrays of magnetic films can produce one-dimensional (1D) and two-dimensional (2D) magnetic lattices with non-zero potential minima, allowing ultracold atoms to be trapped without losses due to spin flips. In particular, we show that two crossed layers of periodic arrays of parallel rectangular magnets plus bias fields, or a single layer of periodic arrays of square-shaped magnets with three different thicknesses plus bias fields, can produce 2D magnetic lattices of microtraps having non-zero potential minima and controllable trap depth. For arrays with micron-scale periodicity, the magnetic microtraps can have very large trap depths ($\sim$0.5 mK for the realistic parameters chosen for the 2D lattice) and very tight confinement.
Abstract We introduce 3D permanent magnetic lattices for ultracold atoms which can be created by arbitrary number of 2D arrays of square permanent magnetic slabs plus a bias magnetic field. Instead of the square magnets, we can also use magnetic films with square holes. We find analytical expressions for the location of the nonzero magnetic field minima and physical quantities such as trap depths, absolute value of the magnetic field and curvatures as well as trap frequencies at each minimum. We show that most of them, including the trap depths, modulation depths, and trap frequencies can be controlled by the bias field. Accessible trap depths and trap frequencies in the permanent magnetic lattices are much higher compared to the optical lattices. Between the magnetic layers, the trap frequencies are higher compared to above the top layer (under the bottom layer). In principle, our method can be generalized to other 2D permanent magnetic lattices and we show how to transform a 2D lattice of a given geometry into 3D by using multiple layers of magnets.