Synopsis: Turning backaction around

Signal amplification in an optical interferometer may push the sensitivity of measurements beyond the standard quantum limit.
Synopsis figure
Illustration: Courtesy of A. Heidmann, Laboratoire Kastler Brossel

Optical techniques that have been developed to measure small displacements are important for gravitational wave astronomy, the detection of currents in superconductors, and the study of quantum effects in mechanical systems. Optical interferometry is unsurpassed in its ability to detect small displacements, but runs into a sensitivity limit known as the standard quantum limit, which results from quantum fluctuations in the light probe itself disturbing the object being measured.

In a paper appearing in Physical Review Letters, Pierre Verlot and colleagues at Laboratoire Kastler Brossel in Paris demonstrate that radiation pressure induced “backaction” fluctuations of the mirror position in an optical interferometer can amplify a signal imprinted on the interferometer light. An amplification factor greater than six was observed by tuning the signal modulation frequency close to the frequency of a cavity mechanical resonance. Although the sensitivity of the current experiment was limited by thermal noise, the amplification technique has the potential to surpass the standard-quantum limit, which would open up new frontiers in precision optical interferometry. – Mark Saffman


Features

More Features »

Subject Areas

Quantum InformationOptics

Previous Synopsis

Fluid Dynamics

Drying out in 3D

Read More »

Next Synopsis

Related Articles

Viewpoint: Cloud Quantum Computing Tackles Simple Nucleus
Nuclear Physics

Viewpoint: Cloud Quantum Computing Tackles Simple Nucleus

Researchers perform a quantum computation of the binding energy of the deuteron using a web connection to remote quantum devices. Read More »

Synopsis: Metamaterials Could Produce Flying Doughnuts
Optics

Synopsis: Metamaterials Could Produce Flying Doughnuts

A proposed scheme for generating torus-shaped light pulses called flying doughnuts utilizes a metamaterial “sprinkled” with tiny resonators in a concentric ring pattern. Read More »

Viewpoint: Landauer Principle Stands up to Quantum Test
Quantum Information

Viewpoint: Landauer Principle Stands up to Quantum Test

A fundamental limit on the heat produced when erasing a bit of information has been confirmed in a fully quantum system. Read More »

More Articles