Certification of Quantum Measurements and New Entangled Quantum Probes
Prof. Gerardo Ortiz
Departement of Physics, Indiana University, Bloomington, USA
Max Planck Institute of Quantum Optics
Herbert Walther Lecture Hall
In the quantum information literature, self-testing refers to the action of uniquely determining a quantum state based solely on the statistics of measurement outcomes and minimal assumptions. These quantum self-testing protocols are more stringent than well-known Bell tests. While violation of a Bell inequality for a bipartite system establishes that its quantum state is entangled, it cannot certify, for instance, that its quantum state is maximally entangled. We extend self-testing techniques to certification of quantum measurements in various physical settings.
In particular, and because of its importance for realizing the topological qubit, we present a quantum self-testing protocol to certify measurements of fermion parity involving Majorana modes, a smoking gun for Majorana fermion detection. Another application is in the realm of new quantum probes of matter. I will present a fundamentally new quantum probe, an entangled neutron beam, where individual neutrons can be entangled in spin, trajectory and energy. Its tunable entanglement length from nanometers to microns and energy differences from peV to neV opens a pathway to a future era of entangled neutron scattering in matter. We developed an interferometer to prove entanglement of these distinguishable properties of the neutron beam by observing clear violations of both Clauser-Horne-Shimony-Holt and Mermin contextuality inequalities in the same experimental setup.