Key Exporter Issue: Qiskit Circuit with Sqrt(X) Dagger Gate Fails QASM Encode

[MattePalte]

Expected behavior
We expect to be able to convert a Qiskit circuit to a BQSKit circuit and then save it as a QASM file without any issues.

Actual behavior
The conversion and saving process fails with an AttributeError when trying to save the QASM file.

Additional information
This issue seems to be related to the sxdg gate (Sqrt(X) dagger) in the Qiskit circuit. The error occurs because BQSKit's DaggerGate object does not have a _qasm_name attribute, which is required for QASM encoding.

Source code

# Qiskit circuit creation
from qiskit import QuantumCircuit, QuantumRegister, ClassicalRegister
qr = QuantumRegister(1, name='qr')
cr = ClassicalRegister(1, name='cr')
qc = QuantumCircuit(qr, cr, name='qc')
qc.sxdg(qr[0])
qc.measure(qr, cr)

# BQSKit conversion and saving
from bqskit.ext import qiskit_to_bqskit
circuit = qiskit_to_bqskit(qc)
circuit.save('check.qasm')
# Output: (AttributeError is raised)
# AttributeError: 'DaggerGate' object has no attribute '_qasm_name'

Tracebacks

AttributeError                            Traceback (most recent call last)
Cell In[9], line 3
      1 from bqskit.ext import qiskit_to_bqskit
      2 circuit = qiskit_to_bqskit(qc)
----> 3 circuit.save('check.qasm')

File ../site-packages/bqskit/ir/circuit.py:3246, in Circuit.save(self, filename)
   3243 language = get_language(filename.split('.')[-1])
   3245 with open(filename, 'w') as f:
-> 3246     f.write(language.encode(self))

File ../site-packages/bqskit/ir/lang/qasm2/qasm2.py:29, in OPENQASM2Language.encode(self, circuit)
     26     source += gate.get_qasm_gate_def()
     28 for op in circuit:
---> 29     source += op.get_qasm()
     31 return source

File ../site-packages/bqskit/ir/operation.py:101, in Operation.get_qasm(self)
     98 else:
     99     full_params = self.params
--> 101 return self.gate.get_qasm(full_params, self.location)

File ../site-packages/bqskit/ir/gate.py:50, in Gate.get_qasm(self, params, location)
     47 def get_qasm(self, params: RealVector, location: CircuitLocation) -> str:
     48     """Returns the qasm string for this gate."""
     49     return '{}({}) q[{}];\n'.format(
---> 50         self.qasm_name,
     51         ', '.join([str(p) for p in params]),
     52         '], q['.join([str(q) for q in location]),
     53     ).replace('()', '')

File ../site-packages/bqskit/ir/gate.py:38, in Gate.qasm_name(self)
     35 if not self.is_qubit_only():
     36     raise AttributeError('QASM only supports qubit gates.')
---> 38 return getattr(self, '_qasm_name')

AttributeError: 'DaggerGate' object has no attribute '_qasm_name'