Physical resources, as the name suggests, are the fundamental physical building blocks required in the lab (or even in simulations) for implementing a quantum communication protocol. They represent the lowest-level modules in a protocol hierarchy, linking an abstract functionality to a concrete resource. These are the physical resources used in the zoo:
Bell State Measurement
Bell state measurement is termed as the projection of two qubits into one of the four Bell States. It is done operating a Hadamard gate on one qubit and then, operating a C-NOT gate with this qubit as control and the other qubit as target.