Figure 1.

The interaction H_AB specified by Equation (5) can, without loss of generality, be implemented by alternating preparation and measurement of N mutually noninteracting qubits. Each cycle of interaction has two phases: first, A prepares the N qubits and then B measures them, then B prepares the N qubits and A measures them. The qubit array defines a holographic screen $\mathcal{B}$ separating A from B. This screen enforces conditional independence between A and B, and hence functions as a MB. There is no source of classical noise in the interaction; however, there is quantum noise, and hence potential classical communication error, whenever A and B employ different reference frames (e.g. different z-axes) to prepare and measure the qubits. Adapted from Fields and Marcianò (2020b); CC BY license.