Quantum advantage using high-dimensional twisted photons as quantum finite automata

Abstract

https://qworld.net Quantum finite automata (QFA) are basic computational devices that make binary decisions using quantum operations. They are known to be exponentially memory efficient compared to their classical counterparts. Here, we demonstrate an experimental implementation of multiqubit QFAs using the orbital angular momentum (OAM) of single photons. We implement different high-dimensional QFAs encoded on a single photon, where multiple qubits operate in parallel without the need for complicated multi-partite operations. Using two to eight OAM quantum states to implement up to four parallel qubits, we show that a high-dimensional QFA is able to detect the prime numbers 5 and 11 while outperforming classical finite automata in terms of the required memory. Our work benefits from the ease of encoding, manipulating, and deciphering multiqubit states encoded in the OAM degree of freedom of single photons, demonstrating the advantages structured photons provide for complex quantum information tasks.Many scientific efforts are focused on controlling quantum systems, e.g., ions, atoms, electrons, photons, and others, that can be used to perform computational tasks more efficiently than classical computers. One of the simplest computational models is the finite automaton [32], which is a fundamental computational device that makes binary decisions (yes or no) using its finite memory (states) after reading a given input once, symbol by symbol. More than two