Fluid analog models for classical and quantum field theory in curved spacetimes

• Applicant: Dr. Piotr Marecki
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2010 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 157899325

The aim of this extension of the DFG project is to deepen the study of ``analog models'' for classical fields in rotating environments and quantum fields in the presence of stationary bounaries. Such models are typically developed in order to investigate exotic, experimentally inaccessible effects (e.g. due to curvature of spacetime) on simpler systems, with full experimental access. In this project we focus on rotating superfluids as models of rotating spacetimes, and on quantum electromagnetic fields in metallic microcavities as models of quantum fields in the presence of strong external/gravitational fields. Experimental feasibility of the project is based on recent achievements in physics of rotating superfluids (rapidly rotating Bose-Einstein condensates) and on progress in physics of photodetection including near-field enhancements of capabilities of high quantum-efficiency photodiodes. In the case of rotating superfluids we have shown in the first part of the project that sound in the presence of a background vortex flow exhibits surprising phenomena when the diameter of the vortex core is very small. In this case rich families of bound states are present even though in the acoustic spacetime sound corresponds to massless fields (and it is counterintuitive to trap light in a bounded region without a horizon). We have shown this effect to be related to the presence of an ergoregion in the corresponding analog (acoustic) spacetime. In the extended part of the project we investigate the influence of the core size on the sound-scattering cross section, and on the force acting on the vortex due to sound-scattering. In the second branch of the project, dealing with quantum fields, we focus on the study of the reduction of quantum fluctuations in the presence of stationary boundaries or flows of quantum fluids. We have shown, that ground states for such environments exhibit a reduction of quantum fluctuations (with respect to the level of these fluctuations in the vacuum state in the absence of boundaries). In the extended part of the project we develop a detailed design of a detector capable of measuring the fluctuation-reduction for quantum electomagnetic fields in metallic micro-cavities (cavities of cross-section only slightly exceeding the relevant wavelengths; Casimir setups). We focus on determination of the appropriate setup employing judiciously the properties of surface plasmons associated with the boundary of the metal in order to focus the photodetection process. The surface-plasmon contribution to the frequency-position-dependent pattern of fluctuations in relevant setups will be determined with the help of (properly adapted) numerical codes (Finite-Element-Methods) for solving partial-differential-equations in inhomogeneous domains of arbitrary geometry.

• DFG Programme: Research Grants
• International Connection: USA
• Participating Person: Professor Dr. Larry Ford