Experimental demonstration of optimal measurement for unambiguously discriminating asymmetric qudit states

TL;DR

This paper experimentally demonstrates an optimal projective measurement scheme for unambiguously discriminating multiple asymmetric qudit states using photonic orbital angular momentum, advancing high-dimensional quantum information processing.

Contribution

It introduces a feasible projective measurement method for asymmetric qudit states and experimentally verifies it with photonic orbital angular momentum encoding.

Findings

Successfully discriminated asymmetric qudit states with optimal success probability

Implemented the measurement using Laguerre-Gaussian modes of a heralded single photon

Potential applications in quantum key distribution and quantum sensing

Abstract

Identification of nonorthogonal quantum states without error is crucial for various applications in quantum information technology, as well as the foundations of quantum physics. Theoretical studies have proposed measurements that maximize the success probability of unambiguously discriminating quantum states. However, these methods are not always experimentally feasible, which has led most demonstrations to focus on equiprobable symmetric states. Here, we establish a projective measurement scheme that optimally discriminates multiple asymmetric qudit states. We experimentally demonstrate this optimal projective measurement using a photonic orbital angular momentum state, where asymmetric qudit states are encoded in the Laguerre-Gaussian modes of a heralded single-photon state. Our results have broad applications in high-dimensional quantum state-based quantum information processing, including quantum key distribution and quantum sensing.