MG15 - Talk detail

Back to previous page

 Participant

Institution

Session

Accepted

Order

Time

Talk

Title

Abstract

In this talk, I present our recent work on the gravitational field of light in a focused laser beam, modeled as a solution to Maxwell's equations perturbatively expanded in the beam divergence. Using this approach, wave properties of light, such as diffraction, are taken into account that have been neglected in earlier studies. Interesting features of the gravitational field of laser beams become apparent: frame-dragging due to the intrinsic angular momentum of light; a gravitational Faraday effect for parallel co-propagating test beams; the deflection of such test beams for short distances to the source beam. We can expect the gravitational field of light to be extremely weak. However, advancements in sensor technology for oscillating gravitational fields may enable the detection of the effect in the future. Certainly, laser beams would be the suitable sources for such experiments. Furthermore, the properties of light are premises in the foundations of modern physics. Studying the back-reaction of light on the gravitational field could give new fundamental insights to our understanding of space and time as well as classical and quantum gravity.

Pdf file

Session

Accepted

Order

Time

Talk

Title

Abstract

Bose-Einstein condensates (BECs) are very small and extremely cold systems of a large number of atoms. These properties are famously exploited for high precision measurements of forces using atom interferometry. A further way of utilizing BECs as sensors for forces is to measure the forces' effect on the collective oscillations of atoms in BECs. A specific example is the measurement of the thermal Casimir-Polder force. In this poster, it is explained how BECs can be used to measure oscillating gravitational fields. Accelerations due to gravitational fields and their gradients give rise to effective external potentials, oscillations on resonance with elastic modes of BECs lead to the creation of phonons. For strong enough gravitational fields this effect can, in principle, be detected. For weaker gravitational fields, a squeezed probe state can be prepared and its change due to the interaction with the oscillating gravitational field may be measured. We illustrate our experimental proposal with the easily accessible example of the gravitational field of a small oscillating gold sphere.

Pdf file

Session

Accepted

Order

Time

Talk

Title

Abstract

There is an ever growing number of proposals for high precision experiments to measure gravitational effects, from simple Newtonian gravity to gravitational waves and even precision tests of general relativity (GR). In particular, more and more researchers from the fields of quantum optics and quantum opto-mechanics are becoming interested in GR and propose metrological experiments. Usually, such proposals rely heavily on a notion of length. However, in GR, as coordinates have no physical meaning, there is no unique concept for the length of a matter system. In this talk, the conceptual problem of length is addressed for a subset of experimental proposals. In particular, the effect of gravitational fields and acceleration on the frequency spectrum of an optical resonator is discussed in the framework of GR. The optical resonator is modeled as a deformable rod of matter connecting two mirrors. Explicit expressions for the frequency spectrum are given for the case of a small perturbation. Example situations are discussed and a connection is obtained to a relativistic concept of rigidity.

Pdf file

Back to previous page