Quantum coherence of spatial photonic qudits: experimental measurement and path-marker analysis

摘要

Discussions about quantum interference, indistinguishability, and superposition between quantum states go back to the beginning of quantum mechanics. However, the theoretical problem, concerning quantitative measures for quantum coherence, was only recently solved by Baumgratz et al (2014 Phys. Rev. Lett. 113 140401). Since then, many works have explored one of the possible coherence measures: the l(1) norm, which has not yet been obtained experimentally for spatial photonic states in high dimensions. In this article, we study the measurement of spatial qudits quantum coherence. We treat the optical measure-operators as path-markers and show in which condition an interference pattern can be used for measure l(1) norm. We analyze the validity of a l(1) norm measurement method, proposed by Paul and Qureshi (2017 Phys. Rev. A 95 042110), implementing it experimentally in qutrit states, and propose an alternative method for qudits states in which one of their assumptions does not apply.