add to_openqasm

Author: refraction-ray

Diff for: CHANGELOG.md

@@ -6,6 +6,8 @@
 
 - Add new parameter shift gradient API that supports finite measurement shots and the corresponding example scripts
 
+- Add openqasm format transformation method `c.to_openqasm()`
+
 ### Changed
 
 - The inner mechanism for `sample_expectation_ps` is changed to sample representation from count representation for a fast speed

Diff for: tensorcircuit/abstractcircuit.py

@@ -509,6 +509,17 @@ def to_qiskit(self) -> Any:
         qir = self.to_qir()
         return qir2qiskit(qir, n=self._nqubits)
 
+    def to_openqasm(self, **kws: Any) -> str:
+        """
+        transform circuit to openqasm via qiskit circuit,
+        see https://qiskit.org/documentation/stubs/qiskit.circuit.QuantumCircuit.qasm.html
+        for usage on possible options for ``kws``
+
+        :return: circuit representation in openqasm format
+        :rtype: str
+        """
+        return self.to_qiskit().qasm(**kws)  # type: ignore
+
     def draw(self, **kws: Any) -> Any:
         """
         Visualise the circuit.

Diff for: tests/test_circuit.py

@@ -1193,3 +1193,13 @@ def test_gate_count():
     assert c.gate_count(["rx", "multicontrol"]) == 2
     print(c.gate_summary())
     # {'h': 2, 'rx': 1, 'multicontrol': 1, 'toffoli': 3}
+
+
+def test_to_openqasm():
+    c = tc.Circuit(3)
+    c.H(0)
+    c.rz(2, theta=0.2)
+    c.cnot(2, 1)
+    c.rzz(0, 1, theta=-1.0)
+    c.ccx(1, 2, 0)
+    print(c.to_openqasm(formatted=True))