Synopsis: One Very Cold Atom

Researchers have demonstrated a new source of individual helium atoms at picokelvin temperatures, paving the way for testing the entanglement of particles with mass.

Isolating single, ultracold atoms is critical for testing quantum phenomena, including entanglement between particles with mass or other atomic interference effects. Scientists at the Australian National University have developed a new technique for reliably segregating single atoms at temperatures as low as a few hundred picokelvin. Multiple setups of this type could now be combined to generate a set of individual atoms for entanglement experiments.

The researchers, led by Andrew Truscott, magnetically trapped helium-4 atoms in a metastable excited energy state state (He*) and cooled them to below 1 microkelvin, where they formed a Bose-Einstein condensate. They then transferred 104 atoms to an optical dipole trap and flipped their quantum mechanical spin to initiate large two-body losses in which successive collisions of two He* atoms (producing an He+ ion, an electron, and an He atom in the ground state) led to atoms being expelled from the trap two at a time. Thus, if the initial number of He* atoms in the trap was odd, only a single atom remained. By characterizing the momentum distribution of the outgoing atoms, the authors determined the atoms’ temperature, concluding that the source emitted atoms at a temperature of 890 picokelvin.

At such low temperatures, the particles’ extremely long de Broglie wavelengths (10 micrometers) are ideal for observing quantum mechanical effects, allowing, for instance, the test of entanglement between particles with mass. The authors suggest that this could be done by expanding the scheme to a two-well optical trap, generating a pair of single atoms that can be collided to create an entangled pair.

This research is published in Physical Review Letters.

–Katherine Kornei


Features

More Features »

Announcements

More Announcements »

Subject Areas

Atomic and Molecular PhysicsQuantum Physics

Previous Synopsis

Next Synopsis

Related Articles

Synopsis: An Expanding Universe in the Lab
Atomic and Molecular Physics

Synopsis: An Expanding Universe in the Lab

The rapid expansion of a Bose-Einstein condensate can mimic the expansion of the Universe. Read More »

Synopsis: ARPES with Cold Atoms
Atomic and Molecular Physics

Synopsis: ARPES with Cold Atoms

A numerical study outlines how to perform measurements on cold atoms that mimic angle-resolved photoemission spectroscopy studies of solids. Read More »

Viewpoint: Moiré Effect Could Enhance Neutron Interferometry
Gravitation

Viewpoint: Moiré Effect Could Enhance Neutron Interferometry

A new and more flexible neutron interferometer design relies on the moiré effect, in which two periodic patterns are combined to give a longer-period pattern. Read More »

More Articles