Add drawer support for AnnotatedOperations

[enavarro51]

Summary

Fixes #11087

Details and comments

This PR adds support for displaying the details of an AnnotatedOperation in the circuit drawers. If the ControlModifier is used, it displays as a controlled gate would. If InverseModifier or PowerModifier is used, this is appended to the name of the base_op. The power value is rounded to 1 decimal.

This also fixes a bug in the 'text' drawer that would cause it to fail if an AnnotatedOperation was in the circuit.
To do:

• Tests
• Reno

from qiskit import QuantumCircuit
from qiskit.quantum_info import Clifford, random_clifford 
from qiskit.circuit.annotated_operation import AnnotatedOperation, InverseModifier, ControlModifier, PowerModifier 
from qiskit.circuit.library import SGate, SXGate, ZGate

qc = QuantumCircuit(3) 
cliff = random_clifford(2) 
qc.append(cliff, [0, 1])
qc.x(0) 
qc.h(1) 
qc.append(SGate().control(2, ctrl_state=1), [0, 2, 1]) 
qc.ccx(0, 1, 2) 
op1 = AnnotatedOperation(SGate(), [InverseModifier(), ControlModifier(2, 1), PowerModifier(3.29)]) 
qc.append(op1, [0, 1, 2]) 
qc.append(SXGate(), [1]) 
qc.draw('text', style="iqp")

     ┌───────────┐┌───┐                                     
q_0: ┤0          ├┤ X ├──■────■────────────■────────────────
     │  Clifford │├───┤┌─┴─┐  │            │          ┌────┐
q_1: ┤1          ├┤ H ├┤ S ├──■────────────o──────────┤ √X ├
     └───────────┘└───┘└─┬─┘┌─┴─┐┌─────────┴─────────┐└────┘
q_2: ────────────────────o──┤ X ├┤ S - Inv, Pow(3.3) ├──────
                            └───┘└───────────────────┘      

[qiskit-bot]

One or more of the the following people are requested to review this:

• @enavarro51
• @Qiskit/terra-core

[coveralls]

Pull Request Test Coverage Report for Build 7316922398

• 42 of 50 (84.0%) changed or added relevant lines in 3 files are covered.
• 4 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.03%) to 87.542%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
qiskit/visualization/circuit/matplotlib.py	5	13	38.46%

Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/expr.rs	1	93.76%
qiskit/visualization/circuit/matplotlib.py	1	48.07%
crates/qasm2/src/lex.rs	2	92.93%

Totals
Change from base Build 7302309139:	0.03%
Covered Lines:	59203
Relevant Lines:	67628

---

💛 - Coveralls

[alexanderivrii]

Many thanks @enavarro51, this looks amazing! And sorry for the late response.

The only small problem is that there could be multiple control modifiers in the list, for example we may have

op1 = AnnotatedOperation(SGate(), [InverseModifier(), ControlModifier(2, 1), ControlModifier(2)])
qc.append(op1, [0, 1, 2, 3, 4])

This can be easily fixed by combining multiple control modifiers into one and displaying that (please see one of the review comments for detail).

Technically we would not be able to see the number of control modifiers or understand which of the control qubits belong to which modifier, but I think it's completely adequate for displaying purposes. To be pedantic, even when we have a single control modifier and some other modifier, say inverse modifier, we can't know from the picture whether the inverse modifier is applied first and the control modifier is applied second, or the other way around, but it does not really matter since both are semantically equivalent, and again I feel it's completely adequate for displaying purposes.

[alexanderivrii]

This would not work correctly when there are multiple ControlModifiers in the list. The simplest fix would be to use the function _canonicalize_modifiers from annotated_operation.py which would combine multiple control modifiers into one, as follows:

if getattr(op, "modifiers", None):
    canonical_modifiers = _canonicalize_modifiers(op.modifiers)
    for modifier in canonical_modifiers:
        if isinstance(modifier, ControlModifier):
            mod_control = modifier
            break

[alexanderivrii]

Please see the comment in text.py.

[enavarro51]

Got it. I understand that displays are sometimes 'best efforts'. Changes done in 0c79f18.

[alexanderivrii]

Many thanks for the quick updates!