Interrogating Entangled Matter with Entangled Probes

We developed an Entangled Scattering theory that extends the scope of standard scattering approaches to study entangled matter, such as unconventional phases of strongly correlated systems. Our presentation will focus on a neutron beam probe that is entangled in spin and path, although similar ideas also apply to photon probes. Our theory generalizes the ubiquitous van Hove Theory whereby the differential cross-section is written as a particular linear combination of two-point correlation functions. Controlling the degree of entanglement of the neutron probe (e.g., the microscopic spin-echo length) allows us to identify the relevant entangled excitations of the investigated target material. This theory and future experiments that it informs may shed light on complex phases exhibited by novel materials such as multiferroics, unconventional superconductors, quantum spin liquids, and frustrated magnets.