timeline_drawer fails for conditional parameterized gates

[eendebakpt]

Environment

• Qiskit version: 1.2.4
• Python version: 3.12
• Operating system: Windows

What is happening?

The timeline_drawer fails for the parameterized crx gate. The underlying problem might be in the schedulers such as ALAP.

How can we reproduce the issue?

A minimal example shows one working case, and 3 failing cases:

import numpy as np
from qiskit.circuit import QuantumCircuit
from qiskit.transpiler import PassManager, InstructionDurations
from qiskit.transpiler.passes import ALAPScheduleAnalysis, PadDynamicalDecoupling
from qiskit.visualization import timeline_drawer
from qiskit.circuit.library import RXGate

durations = InstructionDurations( [("reset", None, 10),
     ("cz", None, 120), ("cx", None, 120), ("crx", None, 160),
     ("rx", None, 80), ('ry', None, 80), ('rz', None, 0),  ("measure", None, 30_000)]
)
dd_sequence = [RXGate(np.pi/2), RXGate(np.pi/2),RXGate(np.pi/2),RXGate(np.pi/2)]

#%% ALAP + DD works
circ = QuantumCircuit(2)
circ.rx(np.pi/2, 0)
circ.rz(-np.pi/2, 0)

pm = PassManager([ALAPScheduleAnalysis(durations),
                  PadDynamicalDecoupling(durations, dd_sequence)])
circ_dd = pm.run(circ)
timeline_drawer(circ_dd) # works


#%% Only ALAP fails
circ = QuantumCircuit(2)
circ.rx(np.pi/2, 0)
circ.rz(-np.pi/2, 0)
 
pm = PassManager([ALAPScheduleAnalysis(durations)])
circ_dd = pm.run(circ)
timeline_drawer(circ_dd) # fails


#%% CRX fails
circ = QuantumCircuit(2)
circ.rx(np.pi/2, 0)
circ.crx(-np.pi/2, 0, 1)

pm = PassManager([ALAPScheduleAnalysis(durations),
                  PadDynamicalDecoupling(durations, dd_sequence)])
circ_dd = pm.run(circ)
timeline_drawer(circ_dd) # works

#%% Different parameters for the rx
circ = QuantumCircuit(2)
circ.rx(0.1 * np.pi, 0)
circ.barrier()
circ.rx(.9*np.pi, 0)
circ.barrier()

 
pm = PassManager([ALAPScheduleAnalysis(durations),
                  PadDynamicalDecoupling(durations, dd_sequence)])
circ_dd = pm.run(circ)
timeline_drawer(circ_dd) # plots, but how can I specify the duration of the two different rx gates?

The exception generated is TypeError: '>' not supported between instances of 'int' and 'NoneType'

What should happen?

If the gate durations are specified, the schedulers should produce circuits that can be plotted by timeline_drawer.

Any suggestions?

No response