Instruction issued to measure in storage qubit for NV platform

[wkozlowski-tudelft]

This bug was filed against version 0.16

The following SDK code:

        q = Qubit(context.connection)
        epr = context.epr_sockets[0].create_keep()[0]

        q.cnot(epr)
        q.H()

        m2 = epr.measure()
        m1 = q.measure()

        context.connection.flush()

Produces roughly the following pseudo-code:

Initialise storage qubit
Entangle
...Transpiled CNOT...
...Transpiled H...
Measure communication qubit
Measure storage qubit

But as per

netqasm/netqasm/sdk/builder.py

Lines 1127 to 1128 in c1d57f9

	# If compiling for NV, only virtual ID 0 can be used to measure a qubit.
	# So, if this qubit is already in use, we need to move it away first.

, the state in the storage qubit should be first moved to the communication qubit.

Interestingly, swapping the order of measurement between epr and q then produces code that tries to move the epr to a storage qubit.