Search

We study possibilities of creation and detection of oscillating gravitational fields from lab-scale high energy, relativistic sources. The sources considered are high energy laser beams in an optical cavity and the ultra-relativistic proton bunches circulating in the beam of the large hadron collider (LHC) at CERN. These sources allow for signal frequencies much higher and far narrower in bandwidth than what most celestial sources produce. In addition, by modulating the beams, one can adjust the source frequency over a very broad range, from Hz to GHz. The gravitational field of these sources and responses of a variety of detectors are analyzed. We optimize a mechanical oscillator such as a pendulum or torsion balance as detector and find parameter regimes such that—combined with the planned high-luminosity upgrade of the LHC as a source—a signal-to-noise ratio substantially larger than 1 should be achievable at least in principle, neglecting all sources of technical noise. This opens new perspectives of studying general relativistic effects and possibly quantum-gravitational effects with ultra-relativistic, well-controlled terrestrial sources., Open Access Publishing Fund of University of Tübingen, Marie Skłodowska-Curie Action IF Programm - Project-Name ‘Phononic Quantum Sensors for Gravity’ (PhoQuS-G), Peer Reviewed

We investigate the rotation of the polarization of a light ray propagating in the gravitational field of a circularly polarized laser beam. The rotation consists of a reciprocal part due to gravitational optical activity, and a non-reciprocal part due to the gravitational Faraday effect. We discuss how to distinguish the two effects: letting light propagate back and forth between two mirrors, the rotation due to gravitational optical activity cancels while the rotation due to the gravitational Faraday effect accumulates. In contrast, the rotation due to both effects accumulates in a ring cavity and a situation can be created in which gravitational optical activity dominates. Such setups amplify the effects by up to five orders of magnitude, which however is not enough to make them measurable with state of the art technology. The effects are of conceptual interest as they reveal gravitational spin–spin coupling in the realm of classical general relativity, a phenomenon which occurs in perturbative quantum gravity., Alexander von Humboldt-Stiftunghttps://doi.org/10.13039/100005156, Peer Reviewed

The recent discovery of gravitational waves by the LIGO-Virgo collaboration created renewed interest in the investigation of alternative gravitational wave detector designs, such as small scale resonant detectors. In this article, it is shown how proposed small scale detectors can be tested by generating dynamical gravitational fields with appropriate distributions of moving masses. A series of interesting experiments will be possible with this setup. In particular, small scale detectors can be tested very early in the development phase and tests can be used to progress quickly in their development. This could contribute to the emerging field of gravitational wave astronomy., Alexander von Humboldt-Stiftunghttps://doi.org/10.13039/100005156, John Templeton Foundationhttps://doi.org/10.13039/100000925, Peer Reviewed

This article was supported by the German Research Foundation (DFG) and the Open Access Publication Fund of Humboldt-Universität zu Berlin., The recent discovery of gravitational waves by the LIGO-Virgo collaboration created renewed interest in the investigation of alternative gravitational wave detector designs, such as small scale resonant detectors. In this article, it is shown how proposed small scale detectors can be tested by generating dynamical gravitational fields with appropriate distributions of moving masses. A series of interesting experiments will be possible with this setup. In particular, small scale detectors can be tested very early in the development phase and tests can be used to progress quickly in their development. This could contribute to the emerging field of gravitational wave astronomy., Alexander von Humboldt-Stiftunghttps://doi.org/10.13039/100005156, John Templeton Foundationhttps://doi.org/10.13039/100000925, Peer Reviewed

We investigate the rotation of the polarization of a light ray propagating in the gravitational field of a circularly polarized laser beam. The rotation consists of a reciprocal part due to gravitational optical activity, and a non-reciprocal part due to the gravitational Faraday effect. We discuss how to distinguish the two effects: letting light propagate back and forth between two mirrors, the rotation due to gravitational optical activity cancels while the rotation due to the gravitational Faraday effect accumulates. In contrast, the rotation due to both effects accumulates in a ring cavity and a situation can be created in which gravitational optical activity dominates. Such setups amplify the effects by up to five orders of magnitude, which however is not enough to make them measurable with state of the art technology. The effects are of conceptual interest as they reveal gravitational spin–spin coupling in the realm of classical general relativity, a phenomenon which occurs in perturbative quantum gravity., Alexander von Humboldt-Stiftunghttps://doi.org/10.13039/100005156, Peer Reviewed

This thesis reviews the conjectured holographic relation between entanglement and gravity due to Mark van Raamsdonk and collaborators. It is accounted how the linearized Einstein equations both with and without matter in a d+1-dimensional AdS background can be derived from the first law of entanglement entropy in a d-dimensional CFT. This derivation builds on the Ryu-Takayanagi formula that relates entanglement entropy for CFT subsystems to extremal surfaces in the AdS bulk. The relation between gravity and entanglement is also corroborated by a qualitative investigation of the duality between the thermofield double state and the maximally extended AdS/Schwarzschild black hole using the Bekenstein-Hawking formula. Furthermore, this qualitative argument is generalized to generic CFT states with a classical spacetime dual using the Ryu-Takayanagi. The thesis also reviews the most relevant prerequisites for this holographic relation between gravity and entanglement: Anti-de Sitter spacetime, entanglement and entanglement entropy, gauge/gravity duality, the Ryu-Takayanagi formula, and linearized gravity.

This thesis reviews the conjectured holographic relation between entanglement and gravity due to Mark van Raamsdonk and collaborators. It is accounted how the linearized Einstein equations both with and without matter in a d+1-dimensional AdS background can be derived from the first law of entanglement entropy in a d-dimensional CFT. This derivation builds on the Ryu-Takayanagi formula that relates entanglement entropy for CFT subsystems to extremal surfaces in the AdS bulk. The relation between gravity and entanglement is also corroborated by a qualitative investigation of the duality between the thermofield double state and the maximally extended AdS/Schwarzschild black hole using the Bekenstein-Hawking formula. Furthermore, this qualitative argument is generalized to generic CFT states with a classical spacetime dual using the Ryu-Takayanagi. The thesis also reviews the most relevant prerequisites for this holographic relation between gravity and entanglement: Anti-de Sitter spacetime, entanglement and entanglement entropy, gauge/gravity duality, the Ryu-Takayanagi formula, and linearized gravity.