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Fundamentals of Entangled Probes for Entangled Matter

Chemistry-Physics Bldg. Room 179
Speaker(s) / Presenter(s):
Prof. Gerardo Ortiz (Indiana University)

Advancing the frontiers of science often requires the creation of new probes to uncover the
underlying microscopic mechanisms giving rise to exotic macroscopic phenomena, such as high-
temperature superconductivity. Can quantum entangled probes uncover the inherent
entanglement of the target matter? We have recently [1-3] developed an entangled neutron
beam where individual neutrons can be entangled in spin, trajectory, and energy. To
demonstrate entanglement in these beams we crafted neutron interferometric measurements
of contextuality inequalities whose violation provided an indication of the breakdown of
Einstein's local realism. In turn, the tunable entanglement (spin-echo) length of the neutron
beam from nanometers to microns and energy differences from peV to neV opens a pathway to
a future era of entangled neutron scattering in matter. What kind of information can be
extracted with this novel entangled probe? A recent general quantum many-body entangled-
probe scattering theory [4] provides a framework to respond to this question. Interestingly, by
carefully tuning the probe's entanglement and inherent coherence properties, one can directly
access the intrinsic entanglement of the target material. This theoretical framework supports
the view that our entangled beam can be used as a multipurpose scientific tool. We are
currently [5] pursuing several ideas and developing new spin-textured entangled beams with
OAM for future experiments in candidate quantum spin liquids, unconventional
superconductors, and chiral quantum materials.

[1] J. Shen et. al., Nature Commun. 11, 930 (2020).
[2] S. Lu et. al., Phys. Rev. A 101, 042318 (2020).
[3] S. J. Kuhn et. al., Phys. Rev. Research 3, 023227 (2021).
[4] A. A. Md. Irfan, P. Blackstone, R. Pynn, and G. Ortiz, New J. Phys. 23, 083022 (2021).
[5] Q. Le Thien, S. McKay, R. Pynn, and G. Ortiz, arXiv:2207.12419.