Atom-hole BECs, condensates of atom-hole pairs held in an "optical
lattice" made of crossed laser beams, might contribute to the now-popular
program of putting quantum weirdness to use in information processing
and to the study of superfluids through the use of tailored interactions.
Chaohong Lee, a physicist at the Max Planck Institute for the Physics
of Complex Systems in Dresden, has suggested his model of atom-hole
condensates in analogy with electron-hole clouds in semiconductors.
When an electron is sprung from its niche in a semiconductor crystal,
the hole remaining behind can itself move around and act as if it were
a positively charged object. Indeed, a nearby electron and hole can
behave as a sort of pair. These pairs, or "excitons," can condense into
a single quantum state. In light emitting diodes (LEDs) the coalescence
of holes and electrons results in light emission.
Lee believes the same can happen to supercold Fermi atoms (those with
a half-integral amount of spin) lodged in all, or nearly all, the interstices
of an optical lattice. In his model two species---with different magnetic
polarizations---of the same element would be loaded in the trap. Then,
by altering an applied magnetic field, interactions among the trapped
atoms, and the potential depth of the optical lattice could be manipulated
so as to favor atom-hole pair formation and even condensation. Like
the electron-hole partners meeting to create light, the atom-hole mates
might also be made to render light in novel ways.(Physical
Review Letters, upcoming article; 49-871-2124, firstname.lastname@example.org)