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Classical conditions misalign in both ASCII and MPL output

See original GitHub issue

Environment

Qiskit Terra version: 0.19.1
Python version: 3.7.12
Operating system: Ubuntu 18.04.5 LTS (Google Colab)

What is happening?

I was testing my automatic code generation for Qiskit, and apparently the ~cphase~ controlled U1 gate with a classical condition will make the circuit misaligns in both of ASCII output and MPL output.

Screenshots:

q2_0: ─■───────■───────■───────■───────■───────■───────■───────■───────■──────»
       │U1(0)  │U1(0)  │U1(0)  │U1(0)  │U1(0)  │U1(0)  │U1(0)  │U1(0)  │U1(0) »
q2_1: ─■───────■───────■───────■───────■───────■───────■───────■───────■──────»
       ║       ║       ║       ║       ║       ║       ║       ║       ║      »
q2_2: ─╫───────╫───────╫───────╫───────╫───────╫───────╫───────╫───────╫──────»
      ┌╫─╨──┐ ┌╫─╨──┐ ┌╫─╨──┐ ┌╫─╨──┐ ┌╫─╨──┐ ┌╫─╨──┐ ┌╫─╨──┐ ┌╫─╨──┐ ┌╫─╨───┐»
c2: 5/╡║0x1 ╞═╡║0x3 ╞═╡║0x5 ╞═╡║0x7 ╞═╡║0x9 ╞═╡║0xb ╞═╡║0xd ╞═╡║0xf ╞═╡║0x11 ╞»
      └╫────┘ └╫────┘ └╫────┘ └╫────┘ └╫────┘ └╫────┘ └╫────┘ └╫────┘ └╫─────┘»
«                                                                         »
«q2_0: ─■───────■───────■───────■───────■───────■───────■───────────■─────»
«       │U1(0)  │U1(0)  │U1(0)  │U1(0)  │U1(0)  │U1(0)  │U1(0) ┌────┴────┐»
«q2_1: ─■───────■───────■───────■───────■───────■───────■──────┤ U2(0,0) ├»
«       ║       ║       ║       ║       ║       ║       ║      └────╥────┘»
«q2_2: ─╫───────╫───────╫───────╫───────╫───────╫───────╫───────────╫─────»
«      ┌╫─╨───┐┌╫─╨───┐┌╫─╨───┐┌╫─╨───┐┌╫─╨───┐┌╫─╨───┐┌╫─╨───┐  ┌──╨──┐  »
«c2: 5/╡║0x13 ╞╡║0x15 ╞╡║0x17 ╞╡║0x19 ╞╡║0x1b ╞╡║0x1d ╞╡║0x1f ╞══╡ 0x2 ╞══»
«      └╫─────┘└╫─────┘└╫─────┘└╫─────┘└╫─────┘└╫─────┘└╫─────┘  └─────┘  »
«                                                                        »
«q2_0: ─────■──────────■──────────■──────────■──────────■──────────■─────»
«      ┌────┴────┐┌────┴────┐┌────┴────┐┌────┴────┐┌────┴────┐┌────┴────┐»
«q2_1: ┤ U2(0,0) ├┤ U2(0,0) ├┤ U2(0,0) ├┤ U2(0,0) ├┤ U2(0,0) ├┤ U2(0,0) ├»
«      └────╥────┘└────╥────┘└────╥────┘└────╥────┘└────╥────┘└────╥────┘»
«q2_2: ─────╫──────────╫──────────╫──────────╫──────────╫──────────╫─────»
«        ┌──╨──┐    ┌──╨──┐    ┌──╨──┐    ┌──╨──┐    ┌──╨──┐    ┌──╨──┐  »
«c2: 5/══╡ 0x3 ╞════╡ 0x6 ╞════╡ 0x7 ╞════╡ 0xa ╞════╡ 0xb ╞════╡ 0xe ╞══»
«        └─────┘    └─────┘    └─────┘    └─────┘    └─────┘    └─────┘  »
«                                                                        »
«q2_0: ─────■──────────■──────────■──────────■──────────■──────────■─────»
«      ┌────┴────┐┌────┴────┐┌────┴────┐┌────┴────┐┌────┴────┐┌────┴────┐»
«q2_1: ┤ U2(0,0) ├┤ U2(0,0) ├┤ U2(0,0) ├┤ U2(0,0) ├┤ U2(0,0) ├┤ U2(0,0) ├»
«      └────╥────┘└────╥────┘└────╥────┘└────╥────┘└────╥────┘└────╥────┘»
«q2_2: ─────╫──────────╫──────────╫──────────╫──────────╫──────────╫─────»
«        ┌──╨──┐    ┌──╨───┐   ┌──╨───┐   ┌──╨───┐   ┌──╨───┐   ┌──╨───┐ »
«c2: 5/══╡ 0xf ╞════╡ 0x12 ╞═══╡ 0x13 ╞═══╡ 0x16 ╞═══╡ 0x17 ╞═══╡ 0x1a ╞═»
«        └─────┘    └──────┘   └──────┘   └──────┘   └──────┘   └──────┘ »
«                                       ┌───────────┐┌───────────┐       »
«q2_0: ─────■──────────■──────────■─────┤ U3(0,0,0) ├┤ U3(0,0,0) ├───X───»
«      ┌────┴────┐┌────┴────┐┌────┴────┐└─────┬─────┘└─────┬─────┘   │   »
«q2_1: ┤ U2(0,0) ├┤ U2(0,0) ├┤ U2(0,0) ├──────■────────────■─────────■───»
«      └────╥────┘└────╥────┘└────╥────┘      ║            ║         │   »
«q2_2: ─────╫──────────╫──────────╫───────────╫────────────╫─────────X───»
«        ┌──╨───┐   ┌──╨───┐   ┌──╨───┐    ┌──╨───┐     ┌──╨───┐  ┌──╨──┐»
«c2: 5/══╡ 0x1b ╞═══╡ 0x1e ╞═══╡ 0x1f ╞════╡ 0x15 ╞═════╡ 0x17 ╞══╡ 0x2 ╞»
«        └──────┘   └──────┘   └──────┘    └──────┘     └──────┘  └─────┘»
«                                                           
«q2_0: ───X──────X──────X──────X───────X───────X───────X────
«         │      │      │      │       │       │       │    
«q2_1: ───■──────■──────■──────■───────■───────■───────■────
«         │      │      │      │       │       │       │    
«q2_2: ───X──────X──────X──────X───────X───────X───────X────
«      ┌──╨──┐┌──╨──┐┌──╨──┐┌──╨───┐┌──╨───┐┌──╨───┐┌──╨───┐
«c2: 5/╡ 0x3 ╞╡ 0xa ╞╡ 0xb ╞╡ 0x12 ╞╡ 0x13 ╞╡ 0x1a ╞╡ 0x1b ╞
«      └─────┘└─────┘└─────┘└──────┘└──────┘└──────┘└──────┘

How can we reproduce the issue?

Using the source code below:

from numpy import pi, e as euler
from qiskit import QuantumCircuit, QuantumRegister, ClassicalRegister
from qiskit.circuit.library.standard_gates import SdgGate, TdgGate, SXGate, RXGate, RYGate, RZGate, U1Gate, U2Gate, U3Gate, SwapGate, XGate, YGate, ZGate, HGate, PhaseGate, SGate, TGate

qr = QuantumRegister(3)
cr = ClassicalRegister(5)
qc = QuantumCircuit(qr, cr)

qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 1)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 3)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 5)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 7)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 9)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 11)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 13)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 15)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 17)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 19)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 21)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 23)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 25)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 27)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 29)
qc.append(U1Gate(0).control(1), [1, 0]).c_if(cr, 31)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 2)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 3)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 6)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 7)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 10)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 11)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 14)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 15)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 18)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 19)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 22)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 23)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 26)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 27)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 30)
qc.append(U2Gate(0, 0).control(1), [0, 1]).c_if(cr, 31)
qc.append(U3Gate(0, 0, 0).control(1), [1, 0]).c_if(cr, 21)
qc.append(U3Gate(0, 0, 0).control(1), [1, 0]).c_if(cr, 23)
qc.append(SwapGate().control(1), [1, 0, 2]).c_if(cr, 2)
qc.append(SwapGate().control(1), [1, 0, 2]).c_if(cr, 3)
qc.append(SwapGate().control(1), [1, 0, 2]).c_if(cr, 10)
qc.append(SwapGate().control(1), [1, 0, 2]).c_if(cr, 11)
qc.append(SwapGate().control(1), [1, 0, 2]).c_if(cr, 18)
qc.append(SwapGate().control(1), [1, 0, 2]).c_if(cr, 19)
qc.append(SwapGate().control(1), [1, 0, 2]).c_if(cr, 26)
qc.append(SwapGate().control(1), [1, 0, 2]).c_if(cr, 27)

qc.draw() # For ASCII output
# qc.draw('mpl') # For MPL output

What should happen?

They should align in a vertical manner.

Any suggestions?

No response

Issue Analytics

State:
Created 2 years ago
Comments:7 (7 by maintainers)

Top GitHub Comments

1reaction

javabstercommented, Feb 16, 2022

i’d be hesitant to remove the side text gates completely just because a bug might be difficult to fix. The user’s experience should come first, and the side text gates have been in use for a while so removing them would probably have a negative impact on all users as opposed to just the handful that experience this bug.

0reactions

enavarro51commented, Feb 18, 2022

That was my most likely conclusion as well, so that’s what I did in #7673.

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