20-07-2012, 12:58 PM
Ultracold Atoms
[attachment=28173]
Bose-Einstein Condensation
Seven JILA scientists investigate Bose- Einstein condensation. Eric Cornell and Deborah Jin head experimental
groups engaged in these studies. Jun Ye and Dana Anderson contribute their expertise in atom optics, ultrafast
optics, and precision measurement to the effort to define and understand this exotic form of matter. John Bohn, Chris
Greene, Murray Holland, and Ana Maria Rey contribute theoretical analyses that help explain experimental findings
and guide future investigations.
Eric Cornell and Deborah Jin are currently collaborating on an
on-going investigation of strongly interacting Bose-Einstein
condensates (BECs), a study that was originally initiated by Carl
Wieman’s group. In 2001, Cornell and Wieman discovered one
possibility for large attractive interactions: a condensate that shrinks
and then explodes. Another possibility is behavior analogous to that of
superfluid helium. If such dynamics were observed in strongly
interacting BECs, it would help bridge the gap between the physics of
superfluid liquids and ultracold atoms.
Degenerate Fermi Gases
Experimentalists Deborah Jin, Eric Cornell, and Jun Ye, together with
theorists Murray Holland, Ana Maria Rey, and Chris Greene
investigate the physics of ultracold degenerate Fermi gases. Studies
are underway on the crossover region between BEC behavior, where fermion pairs form molecules, and the BCS
(Bardeen-Cooper-Schrieffer) region where fermion pairs form superfluids. The characterization of this crossover
region is increasingly relying on the use of Feshbach resonances. Feshbach resonances are specific values of the
magnetic field where small changes in the field strength cause big changes in the behavior of the atoms in an
ultracold gas. A powerful JILA collaboration is developing these resonances as tools for not only studying Fermi
gases, but also BECs. The collaboration’s goal is to apply a broader understanding of Feshbach resonance physics
to the investigation of antiferromagnetism, superfluidity, and Bose-Fermi interactions.
Superfluidity
The Jin group conducts ongoing experiments to probe superfluidity in
ultracold Fermi gases. The group recently took an important step
towards creating superfluids of molecules whose atoms interact via
p-waves. P-waves involve higher-order pairing of atoms in which the
resulting molecules are rotating; such pairing contrasts with the more
widely studied s-wave pairing in which the resulting molecules do not
rotate. P-wave studies promise to expand the understanding of ultracold Fermi gases gained from s-wave-based
studies of the BEC-BCS crossover. For instance, with p-waves, the group may be able to create a superfluid gas that
involves higher-order pairing, akin to that found in superfluid helium (3He).
Optical Lattices
Optical lattices are potential wells created by the interference patterns
of counterpropagating laser beams. These potential wells can trap
neutral atoms, creating a system that resembles a crystal, with the
atoms in optical lattices being analogous to electrons in solid-state
crystals. Unlike naturally occurring crystals, however, these "artificial
light crystals" are completely regular, without flaws. As such, they are
an ideal quantum system where all parameters can be manipulated
experimentally. They can be used to study effects that are difficult to
observe in real crystals or other condensed matter systems.
[attachment=28173]
Bose-Einstein Condensation
Seven JILA scientists investigate Bose- Einstein condensation. Eric Cornell and Deborah Jin head experimental
groups engaged in these studies. Jun Ye and Dana Anderson contribute their expertise in atom optics, ultrafast
optics, and precision measurement to the effort to define and understand this exotic form of matter. John Bohn, Chris
Greene, Murray Holland, and Ana Maria Rey contribute theoretical analyses that help explain experimental findings
and guide future investigations.
Eric Cornell and Deborah Jin are currently collaborating on an
on-going investigation of strongly interacting Bose-Einstein
condensates (BECs), a study that was originally initiated by Carl
Wieman’s group. In 2001, Cornell and Wieman discovered one
possibility for large attractive interactions: a condensate that shrinks
and then explodes. Another possibility is behavior analogous to that of
superfluid helium. If such dynamics were observed in strongly
interacting BECs, it would help bridge the gap between the physics of
superfluid liquids and ultracold atoms.
Degenerate Fermi Gases
Experimentalists Deborah Jin, Eric Cornell, and Jun Ye, together with
theorists Murray Holland, Ana Maria Rey, and Chris Greene
investigate the physics of ultracold degenerate Fermi gases. Studies
are underway on the crossover region between BEC behavior, where fermion pairs form molecules, and the BCS
(Bardeen-Cooper-Schrieffer) region where fermion pairs form superfluids. The characterization of this crossover
region is increasingly relying on the use of Feshbach resonances. Feshbach resonances are specific values of the
magnetic field where small changes in the field strength cause big changes in the behavior of the atoms in an
ultracold gas. A powerful JILA collaboration is developing these resonances as tools for not only studying Fermi
gases, but also BECs. The collaboration’s goal is to apply a broader understanding of Feshbach resonance physics
to the investigation of antiferromagnetism, superfluidity, and Bose-Fermi interactions.
Superfluidity
The Jin group conducts ongoing experiments to probe superfluidity in
ultracold Fermi gases. The group recently took an important step
towards creating superfluids of molecules whose atoms interact via
p-waves. P-waves involve higher-order pairing of atoms in which the
resulting molecules are rotating; such pairing contrasts with the more
widely studied s-wave pairing in which the resulting molecules do not
rotate. P-wave studies promise to expand the understanding of ultracold Fermi gases gained from s-wave-based
studies of the BEC-BCS crossover. For instance, with p-waves, the group may be able to create a superfluid gas that
involves higher-order pairing, akin to that found in superfluid helium (3He).
Optical Lattices
Optical lattices are potential wells created by the interference patterns
of counterpropagating laser beams. These potential wells can trap
neutral atoms, creating a system that resembles a crystal, with the
atoms in optical lattices being analogous to electrons in solid-state
crystals. Unlike naturally occurring crystals, however, these "artificial
light crystals" are completely regular, without flaws. As such, they are
an ideal quantum system where all parameters can be manipulated
experimentally. They can be used to study effects that are difficult to
observe in real crystals or other condensed matter systems.