Efficient High-Dimensional Entangled State Analyzer with Linear Optics

The use of higher-dimensional photonic encodings (qudits) instead of two-dimensional encodings (qubits) can improve the loss tolerance and reduce the computational resources of photonic-based quantum information processing. To harness this potential, efficient schemes for entangling operations such as the high-dimensional generalization of a linear optics Bell measurement will be required. We show how an efficient high-dimensional entangled state analyzer can be implemented with linear optics and auxiliary photonic states. The Schmidt rank of the auxiliary state in our protocol scales only linearly with the dimensions of the input states instead of more than exponentially, as in previous proposals. In addition, we outline how the state can be generated deterministically from a single quantum emitter coupled to a small qubit processor. Our protocol thus outlines an experimentally feasible route for efficient, high-dimensional entangled state analyzers with linear optics.