Experimental Multi-state Quantum Discrimination in the Frequency Domain with Quantum Dot Light

TL;DR

This paper demonstrates an experimental method for discriminating among eight non-orthogonal quantum states using a frequency domain approach with single photons, advancing high-dimensional quantum information processing.

Contribution

It introduces a novel experimental protocol employing time-multiplexing and linear optics for high-dimensional quantum state discrimination in the frequency domain.

Findings

Successfully discriminated eight non-orthogonal states

Implemented with linear optics and two photodetectors

Paves the way for complex high-dimensional quantum applications

Abstract

The quest for the realization of effective quantum state discrimination strategies is of great interest for quantum information technology, as well as for fundamental studies. Therefore, it is crucial to develop new and more efficient methods to implement discrimination protocols for quantum states. Among the others, single photon implementations are more advisable, because of their inherent security advantage in quantum communication scenarios. In this work, we present the experimental realization of a protocol employing a time-multiplexing strategy to optimally discriminate among eight non-orthogonal states, encoded in the four-dimensional Hilbert space spanning both the polarization degree of freedom and photon energy. The experiment, built on a custom-designed bulk optics analyser setup and single photons generated by a nearly deterministic solid-state source, represents a benchmarking example of minimum error discrimination with actual quantum states, requiring only linear optics and two photodetectors to be realized. Our work paves the way for more complex applications and delivers a novel approach towards high-dimensional quantum encoding and decoding operations.