Quantum Computing Stack Exchange is a question and answer site for engineers, scientists, programmers, and computing professionals interested in quantum computing. It only takes a minute to sign up.
Sign up to join this community
Executing
from qiskit import *
circuit = qiskit.QuantumCircuit(3, 3)
circuit.draw(output="mpl")
in ipython notebook gives the following image
Which looks incomplete. It does not render two other classical registers and also appears to be incorrectly padded. Is my output image really incorrect? How can I fix that?
This is a known issue which was already fixed and will be released in the coming qiskit-terra 0.17.
from qiskit import *
circuit = qiskit.QuantumCircuit(3, 3)
circuit.draw(output="mpl")
This looks alright to me, as you haven't added any gates to your circuit so there isn't anything else that should be displayed. As for the classical registers, they are all represent by the line at the bottom, the 3 shows that there are 3 classical registers. Setting cregbundle to false will draw them as independent lines, so circuit.draw(output="mpl", cregbundle=True).
@met927 looks great. Here is an another example on how you can define different classical register name and having them show up on different wire on your circuit:
qreg_q = QuantumRegister(2, 'qregister')
creg_c1 = ClassicalRegister(1, 'cregister1')
creg_c2 = ClassicalRegister(1, 'cregister2')
circuit = QuantumCircuit(qreg_q, creg_c1, creg_c2)
circuit.h(qreg_q[1])
circuit.cx(qreg_q[0], qreg_q[1])
circuit.measure(qreg_q[0], creg_c1[0])
circuit.measure(qreg_q[1], creg_c2[0])
circuit.draw( 'mpl',style={'name': 'bw'}, scale = 1)
This will give you something like:
