Probing quantum correlation functions through energy-absorption interferometry

Abstract

An interferometric technique is proposed for determining the spatial forms of the individual degrees of freedom through which a many body system can absorb energy from its environment. The method separates out the coherent excitations present at any given frequency; it is not necessary to infer modal content from spectra. The system under test is excited with two external sources, which create generalized forces, and the fringe in the total power dissipated is measured as the relative phase between the sources is varied. If the complex fringe visibility is measured for different pairs of source locations, the anti-Hermitian part of the complex-valued non-local correlation tensor can be determined, which can then be decomposed to give the natural dynamical modes of the system and their relative responsivities. If each source in the interferometer creates a different kind of force, the spatial forms of the individual excitations that are responsible for cross-correlated response can be found. The technique is a generalization of holography because it measures the state of coherence to which the system is maximally sensitive. It can be applied across a wide range of wavelengths, in a variety of ways, to homogeneous media, thin films, patterned structures, and to components such as sensors, detectors and energy harvesting absorbers. arXiv:1609.03174v1 [quant-ph]

Probing infrared detectors through energy-absorption interferometry

“…4 It was also shown by Withington that EAI can be further generalized to account for quantum correlations and probes acting through different forces on the surface under test. 12 Each of these cases could give rise to an experimental demonstration of its own, improve our understanding of the coupling of incident fields into absorbing structures, reveal the influence of design choices such as geometries and fabrication properties, and allow the optimization of both detectors and any preceding instrumentation. The experimental demonstration for the case of near-infrared detectors described here therefore also represents a strong step forward towards each of these goals.…”

Characterization of power absorption response of periodic three-dimensional structures to partially coherent fields

“…Recording the powers absorbed for different positions and phase difference between sources, it is possible to predict the power absorbed by the structure when illuminated by any incident fields. EAI can be implemented experimentally in many different ways, and over a wide range of wavelengths [10], depending on the way the SUT is illuminated (e.g: near-field probes, far field radiators) and the way the power absorbed by the sample is recorded. The power absorption can be measured directly when the SUT corresponds to photovoltaics and electromagnetic detectors, while, for other types of structures, the absorption can be recorded through the local temperature rise using bolometric calorimeters.…”

“…In this section, we will provide a link between the data that can be gathered using EAI, which corresponds to the spatial correlation function C(r 1 , r 2 ), and the cross-spectral power density function P o (k t , k t ) as defined in (10). Starting from the definition of the correlation function given in (31), we can use (27) to obtain…”

“…Thus, equation (19) must be used instead of Equation (40). Adapting the phase of the correlation between the different quasiperiodic components of the source, it is possible to compute the power dissipated in any unit-cell (see (10)).…”

“…The same considerations apply to near-field energy and information transfer between separated or overlapping volumes. In a recent paper [10], the method has been extended to recovering the collective excitations of quantum-mechanical systems.…”