2025/12/02 by Shah, Ronit
Physics and Astronomy · Computer Science · Engineering · #Quantum Mechanics and Applications #Quantum Information and Cryptography #Wireless Communication Security Techniques
paper · pdf · doi:10.48550/arxiv.2512.02477
We consider the following simple scenario: Alice has one of many possible messages, drawn from a known distribution, and wants to maximize the probability that Bob guesses her message correctly. We prove that if Alice can send only a qudit to Bob, without preshared entanglement, there is never any advantage over sending him a classical dit. This result was previously known only for a uniform distribution. We also prove a mixed-state generalization of this result in the form of an upper bound on the success probability of discriminating between mixed quantum states with a single measurement. This bound is based solely on the dimension, probability distribution, and eigenvalues of the states and is sharp among such bounds.