Elementary Theory of Interferometry

Ch. J. Bordé

Ojas Parekh

Decoded Quantum Interferometry (DQI) is a framework for approximating special kinds of discrete optimization problems that relies on problem structure in a way that sets it apart from other classical or quantum approaches. We show that any family of instances of MaxCut on which DQI attains a nontrivial asymptotic approximation guarantee is also solvable exactly in classical polynomial time. We include a streamlined exposition of DQI tailored for MaxCut that relies on elementary graph theory instead of coding theory to motivate and explain the algorithm.

Peter Hawkes, Erwin K. Kasper

Z. Hradil, Jaroslav Řeháček

Diffraction on the slit can be interpreted in accordance with the Heisenberg uncertainty principle. This elementary example hints at the importance of the information theory for the quantum physics. The role played by one particularly interesting measure of information -- the Fisher information -- in quantum measurements is further discussed in the context of quantum interferometry.

Bernard F. Burke, F. G. Smith, Peter N. Wilkinson

Markus Arndt, Klaus Hornberger

This chapter reviews recent experiments on matter wave interferometry with large molecules. Starting from an elementary introduction to matter wave physics we discuss far-field diffraction and near-field interferometry with thermally excited many-body systems. We describe the constraints imposed by decoherence and dephasing effects, and present an outlook to the future challenges in macromolecule and cluster interferometry.