Experimental investigation of wave-particle duality relations in asymmetric beam interference

Abstract

Wave-particle duality relations are fundamental for quantum physics. Previous experimental studies of duality relations mainly focus on the quadratic relation D2 + V2 ≤ 1, based on symmetric beam interference, while a linear form of the duality relation, predicated earlier theoretically, has never been experimentally tested. In addition, the difference between the quadratic form and the linear form has not been explored yet. In this work, with a designed asymmetric beam interference and by utilizing the polarization degree of freedom of the photon as a which-way detector, we experimentally confirm both forms of the duality relations. The results show that more path information is obtained in the quadratic case. Our findings reveal the difference between the two duality relations and have fundamental implications in better understanding these important duality relations.

Experimental demonstration of separating the wave‒particle duality of a single photon with the quantum Cheshire cat

“…However, after Wheeler's "delayed-choice experiment" 7,8 and its recent quantum versions 9 , quantum wave-particle superposition, in which both the wave and particle attributes are observed simultaneously, has been realized in experiments, including those using a single photon 10,11 and two entangled photons 12 . Recently, several outstanding works exploring profound connotation in wave-particle duality have been conducted, including the investigation of the linear form of duality relation with asymmetric beam interference 13 , the experimental progress in the large-scale quantum nanophotonic chip 14 , and theoretical achievements with the electron 15 . Although a series of outstanding theoretical and experimental works that deepen the understanding of wave-particle duality have been reported, it remains unclear which path a single photon (or any other particle) takes when it enters the MZI (double-slit setup).…”