Quantum Identification Capacities: Comparing Pure State Encoders and Simultaneous Decoders

The authors analyze the identification capacities of quantum channels under different constraints on the encoder and decoder, including pure state encoders and simultaneous decoders. They show that pure state encoders can achieve double exponential growth in the number of identifiable messages, matching the capacity of general encoders, and that the simultaneous identification capacity equals the capacity with pure state encoders.