Synopsis: Raman thermometer for fermions

Raman spectroscopy has been put to use in measuring temperature and correlations of ultracold fermionic atoms loaded into an optical lattice.
Synopsis figure
Illustration: Courtesy of J.-S. Bernier et al.

Ultracold atoms in optical lattices have recently been all the rage for their fundamental and technological promise. The ability to tune interactions, dimensionality, spin, statistics, and a host of other variables in a completely disorder-free environment opens the possibility for these systems to be used as emulators of model Hamiltonians that describe complex materials. However, measuring their temperature remains a practical challenge as few promising schemes are known. A suitable measurable property is needed such that its magnitude is in a one-to-one correspondence with the temperature of the system.

Writing in Physical Review A, Jean-Sébastien Bernier and collaborators from France and Argentina have demonstrated how to make use of a rather unusual thermometric property—the Raman transition rate for a fermionic gas. For a wide range of well-specified conditions, the Raman signal depends on temperature only via the Fermi distribution function. To implement the method, one simply measures the Raman spectrum of the gas.

Bernier et al. go beyond the thermometric aspect and predict distinct features in the respective Raman spectra, fingerprints as it were, of various regimes of correlation (weak correlations, strongly correlated Fermi liquid, and a Mott insulating phase). The predicted signatures, such as the emergence of broad Hubbard bands in the incompressible Mott regime, would survive at ultralow temperatures and provide for diagnostics of the degree of correlation in 2D and 3D fermionic gases in optical lattices. Naturally, this would also serve to map out the phase diagram of ultracold correlated systems. – Yonko Millev


Features

More Features »

Announcements

More Announcements »

Subject Areas

Atomic and Molecular Physics

Next Synopsis

Quantum Information

Quantum guessing games

Read More »

Related Articles

Synopsis: Quantum Sensing of Magnetic Fields
Quantum Physics

Synopsis: Quantum Sensing of Magnetic Fields

A new design for an atomic magnetometer utilizes so-called quantum nondemolition measurements to detect very weak magnetic-field signals. Read More »

Focus: New View of Cold Atoms Flowing
Atomic and Molecular Physics

Focus: New View of Cold Atoms Flowing

A new technique produces an image of the flow of cold atoms through a channel, a potentially important tool for future cold-atom technology. Read More »

Viewpoint: Seeing Scrambled Spins
Atomic and Molecular Physics

Viewpoint: Seeing Scrambled Spins

Two experimental groups have taken a step towards observing the “scrambling” of information that occurs as a many-body quantum system thermalizes.   Read More »

More Articles