(4,1)-Quantum random access coding does not exist—one qubit is not enough to recover one of four bits

An ( n ,1, p )-quantum random access (QRA) coding, introduced by Ambainis et al (1999 ACM Symp. Theory of Computing p 376), is the following communication system: the sender which has n -bit information encodes his/her information into one qubit, which is sent to the receiver. The receiver can recov... View More