Quantum Entangled-Probe Scattering Theory

TL;DR

This paper introduces an entangled-probe scattering theory that utilizes quantum entanglement in probes like neutrons or photons to study complex matter, revealing new interference phenomena related to entanglement.

Contribution

It generalizes traditional scattering theory to include entangled probes, enabling the study of entangled matter and revealing entanglement-dependent interference effects.

Findings

Entangled probes can interrogate spatial scales via interference patterns.

Maximal entanglement in the target erases classical interference patterns.

The theory extends van Hove's approach to include quantum entanglement effects.

Abstract

We develop an entangled-probe scattering theory, including quantum detection, that extends the scope of standard scattering approaches. We argue that these probes may be revolutionary in studying entangled matter such as unconventional phases of strongly correlated systems. Our presentation focuses on a neutron beam probe that is mode-entangled in spin and path as is experimentally realized in [1], although similar ideas also apply to photon probes. We generalize the traditional van Hove theory [2] whereby the response is written as a properly-crafted combination of two-point correlation functions. Tuning the probe's entanglement length allows us to interrogate spatial scales of interest by analyzing interference patterns in the differential cross-section. Remarkably, for a spin dimer target we find that the typical Young-like interference pattern observed if the target state is un-entangled gets quantum erased when that state becomes maximally entangled.