Probing Quantum Correlation Functions Through Energy Absorption Interferometry

TL;DR

This paper introduces an interferometric method to directly probe the spatial structure of energy-absorbing modes in many-body systems, enabling detailed insight into their coherence and response characteristics without spectral inference.

Contribution

The proposed technique generalizes holography to measure the coherence state of energy absorption modes, providing a new way to analyze dynamical modes in various media and structures.

Findings

Determines the non-local correlation tensor of the system.

Decomposes the tensor to identify natural dynamical modes.

Applicable across different wavelengths and media.

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.