Synopsis: Photons gained, photons lost

A new photon-counting technique is proposed for detecting excitations of an ultracold gas of atoms.
Synopsis figure
Credit: J. M. Pino et al., Phys. Rev. A (2011)

Studying spectra resulting from excitations is a standard tool to investigate many-body systems. In Bragg spectroscopy of ultracold atomic gases—a scattering process where a driving field subjects a gas to a perturbation—such spectra can be directly compared with theory. The system’s response to the perturbation is usually measured with a time-of-flight imaging technique of the atomic cloud. This method, however, is not particularly useful for low-momentum excitations and strong interactions, where the response of the system to the driving field can be hard to quantify.

In a paper published in Physical Review A, J. M. Pino and colleagues at JILA and at the University of Colorado get around this difficulty with a new technique, which measures the probing field’s complementary reaction to the gas. They count the photons gained or lost in one of the laser fields used to drive the excitations, using techniques that improve sensitivity by minimizing the effects of noise.

An interesting and powerful new feature of the photon-counting measurement technique is that, in contrast to the time-of-flight technique, it can be used to probe the dynamics of Bragg excitations during a single laser pulse. – Franco Dalfovo and Jihane Mimih


Features

More Features »

Announcements

More Announcements »

Subject Areas

Optics

Previous Synopsis

Next Synopsis

Soft Matter

Gels settle down

Read More »

Related Articles

Viewpoint: Transportable Clocks Move with the Times
Optics

Viewpoint: Transportable Clocks Move with the Times

Transportable atomic clocks are now operating with fractional-frequency uncertainties below one part in 1016, opening up new applications. Read More »

Viewpoint: Trapped Ions Stopped Cold
Optics

Viewpoint: Trapped Ions Stopped Cold

A novel method for cooling trapped ions could boost the accuracy of atomic clocks. Read More »

Focus: Light Pushes and Pulls
Mechanics

Focus: Light Pushes and Pulls

Two forces coming from a light beam—one based on momentum transfer, the other on thermal effects—drive a tiny gold plate to move in opposite directions. Read More »

More Articles