Synopsis: Bouncing in a Spacetime Ripple

Microparticles suspended in an optical cavity may be a new way to detect gravity waves.
Synopsis figure
A. Arvanitaki and A. Geraci, Phys. Rev. Lett. (2013)

Everything tells us that moving masses should emit gravitational waves, but despite strong indirect evidence, there have been no direct detections. Large international collaborations are now using highly sensitive laser interferometers to look for gravity waves, requiring heroic measures to reduce noise and raise sensitivity. These detectors, however, are optimized for wave frequencies below 10 kilohertz, causing them to miss potentially important events. In a paper in Physical Review Letters, Asimina Arvanitaki at Stanford University, California, and Andrew Geraci at the University of Nevada in Reno propose using microparticles trapped in an optical cavity as a new kind of high-frequency gravitational wave detector.

The authors consider the theoretical possibility of using a small sphere or disk suspended by radiation forces to detect gravitational waves. They propose trapping this tiny particle in a standing wave produced by an optical cavity and reducing its motion to a minimum with laser cooling. A passing gravitational wave would then produce a small ripple in spacetime causing a change in mirror spacing, shifting the location where the particle is trapped. The altered position of the particle is detected using light reflected from the cavity. For a 75-micron particle in a 100-meter-long cavity, Arvanitaki and Geraci estimate that they can exceed the sensitivity of the larger gravitational wave observatories for wave frequencies around 100 kilohertz.

In their paper, the authors frankly acknowledge that few gravitational wave sources are expected to exist at this frequency, but Arvanitaki and Geraci do consider one exotic possibility. Theoretically predicted particles called axions might form a cloud around a black hole, and these in turn might annihilate to produce gravitons that create gravitational waves at the right frequency for detection by levitating microspheres. – David Voss


More Announcements »

Subject Areas

OpticsParticles and FieldsGravitation

Previous Synopsis


Surface Protection

Read More »

Next Synopsis

Quantum Information

Hitting Reset After a Quantum Measurement

Read More »

Related Articles

Synopsis: Testing Gravity On Solar System Scales

Synopsis: Testing Gravity On Solar System Scales

A proposed space mission would precisely measure deviations from Newtonian gravity on a scale of 100 astronomical units. Read More »

Viewpoint: Connecting the Higgs Mass with Cosmic History

Viewpoint: Connecting the Higgs Mass with Cosmic History

A theoretical proposal ties the puzzling light mass of the Higgs particle to a hypothetical new particle that plays an important role during the big bang. Read More »

Synopsis: LHC Data Might Reveal Nature of Neutrinos
Particles and Fields

Synopsis: LHC Data Might Reveal Nature of Neutrinos

A long-standing question over whether the neutrino is its own antiparticle might be answered by looking at decays of W bosons. Read More »

More Articles