fix issue with conditional and symbolic parameter in conversion (#245)

* fix conditional and symbolic parameter in conversion

* remove linebreak from error message

* use numpy.pi

* remove qasm from error message

Author: cqc-melf

docs/changelog.rst

@@ -8,7 +8,8 @@ General:
 
 * Python 3.12 support added, 3.9 dropped.
 * pytket dependency updated to 1.24.
-
+* fix conditional bit in pytket to qiskit conversion
+* fix symbolic conversion of parameter in conversion
 
 0.47.0 (January 2024)
 ---------------------

pytket/extensions/qiskit/qiskit_convert.py

@@ -52,6 +52,7 @@
     Parameter,
     ParameterExpression,
     Reset,
+    Clbit,
 )
 from qiskit.circuit.library import (
     CRYGate,
@@ -342,11 +343,23 @@ def add_qiskit_data(self, data: "QuantumCircuitData") -> None:
         for instr, qargs, cargs in data:
             condition_kwargs = {}
             if instr.condition is not None:
-                cond_reg = self.cregmap[instr.condition[0]]
-                condition_kwargs = {
-                    "condition_bits": [cond_reg[k] for k in range(len(cond_reg))],
-                    "condition_value": instr.condition[1],
-                }
+                if type(instr.condition[0]) == ClassicalRegister:
+                    cond_reg = self.cregmap[instr.condition[0]]
+                    condition_kwargs = {
+                        "condition_bits": [cond_reg[k] for k in range(len(cond_reg))],
+                        "condition_value": instr.condition[1],
+                    }
+                elif type(instr.condition[0]) == Clbit:
+                    cond_reg = self.cregmap[instr.condition[0].register]
+                    condition_kwargs = {
+                        "condition_bits": [cond_reg[instr.condition[0].index]],
+                        "condition_value": instr.condition[1],
+                    }
+                else:
+                    raise NotImplementedError(
+                        "condition must contain classical bit or register"
+                    )
+
             # Controlled operations may be controlled on values other than all-1. Handle
             # this by prepending and appending X gates on the control qubits.
             ctrl_state, num_ctrl_qubits = None, None
@@ -653,22 +666,29 @@ def append_tk_command_to_qiskit(
             width = op.width  # type: ignore
             value = op.value  # type: ignore
         regname = args[0].reg_name
-        if len(cregmap[regname]) != width:
-            raise NotImplementedError("OpenQASM conditions must be an entire register")
         for i, a in enumerate(args[:width]):
             if a.reg_name != regname:
-                raise NotImplementedError(
-                    "OpenQASM conditions can only use a single register"
-                )
-            if a.index != [i]:
-                raise NotImplementedError(
-                    "OpenQASM conditions must be an entire register in order"
-                )
+                raise NotImplementedError("Conditions can only use a single register")
         instruction = append_tk_command_to_qiskit(
             op.op, args[width:], qcirc, qregmap, cregmap, symb_map, range_preds  # type: ignore
         )
+        if len(cregmap[regname]) == width:
+            for i, a in enumerate(args[:width]):
+                if a.index != [i]:
+                    raise NotImplementedError(
+                        """Conditions must be an entire register in\
+ order or only one bit of one register"""
+                    )
+
+            instruction.c_if(cregmap[regname], value)
+        elif width == 1:
+            instruction.c_if(cregmap[regname][args[0].index[0]], value)
+        else:
+            raise NotImplementedError(
+                """Conditions must be an entire register in\
+order or only one bit of one register"""
+            )
 
-        instruction.c_if(cregmap[regname], value)
         return instruction
     # normal gates
     qargs = [qregmap[q.reg_name][q.index[0]] for q in args]
@@ -719,7 +739,10 @@ def append_tk_command_to_qiskit(
         ) from error
     params = _get_params(op, symb_map)
     g = gatetype(*params)
-    qcirc.global_phase += phase * sympy.pi
+    if type(phase) == float:
+        qcirc.global_phase += phase * np.pi
+    else:
+        qcirc.global_phase += phase * sympy.pi
     return qcirc.append(g, qargs=qargs)
 
 

tests/qiskit_backend_test.py

@@ -22,8 +22,6 @@
 from qiskit.primitives import BackendSampler  # type: ignore
 from qiskit.providers import JobStatus  # type: ignore
 from qiskit_algorithms import Grover, AmplificationProblem, AlgorithmError  # type: ignore
-from qiskit.transpiler import PassManager  # type: ignore
-from qiskit.transpiler.passes import Unroller  # type: ignore
 from qiskit_aer import Aer  # type: ignore
 
 from qiskit_ibm_provider import IBMProvider  # type: ignore

tests/qiskit_convert_test.py

@@ -24,14 +24,17 @@
     ClassicalRegister,
     execute,
 )
-from qiskit.quantum_info import SparsePauliOp  # type: ignore
+from qiskit.quantum_info import SparsePauliOp, Statevector, Operator  # type: ignore
 from qiskit.transpiler import PassManager  # type: ignore
 from qiskit.circuit.library import RYGate, MCMT, XXPlusYYGate, PauliEvolutionGate, UnitaryGate, RealAmplitudes  # type: ignore
 import qiskit.circuit.library.standard_gates as qiskit_gates  # type: ignore
 from qiskit.circuit import Parameter
 from qiskit.synthesis import SuzukiTrotter  # type: ignore
 from qiskit_aer import Aer  # type: ignore
-from qiskit.quantum_info import Statevector, Operator
+from qiskit.transpiler.passes import BasisTranslator  # type: ignore
+from qiskit.circuit.equivalence_library import StandardEquivalenceLibrary  # type: ignore
+from qiskit.providers.fake_provider import FakeGuadalupe  # type: ignore
+from qiskit.circuit.parameterexpression import ParameterExpression  # type: ignore
 
 from pytket.circuit import (
     Circuit,
@@ -50,7 +53,14 @@
 from pytket.extensions.qiskit.qiskit_convert import _gate_str_2_optype
 from pytket.extensions.qiskit.tket_pass import TketPass, TketAutoPass
 from pytket.extensions.qiskit.result_convert import qiskit_result_to_backendresult
-from pytket.passes import RebaseTket, DecomposeBoxes, FullPeepholeOptimise, SequencePass
+from pytket.passes import (
+    RebaseTket,
+    DecomposeBoxes,
+    FullPeepholeOptimise,
+    SequencePass,
+    CliffordSimp,
+)
+
 from pytket.utils.results import (
     compare_statevectors,
     permute_rows_cols_in_unitary,
@@ -72,6 +82,28 @@ def _get_qiskit_statevector(qc: QuantumCircuit) -> np.ndarray:
     return np.array(job.result().data()["statevector"].reverse_qargs().data)
 
 
+def test_parameterised_circuit_global_phase() -> None:
+    pass_1 = BasisTranslator(
+        StandardEquivalenceLibrary,
+        target_basis=FakeGuadalupe().configuration().basis_gates,
+    )
+    pass_2 = CliffordSimp()
+
+    qc = QuantumCircuit(2)
+    qc.ryy(Parameter("MyParam"), 0, 1)
+
+    pm = PassManager(pass_1)
+    qc = pm.run(qc)
+
+    tket_qc = qiskit_to_tk(qc)
+
+    pass_2.apply(tket_qc)
+
+    qc_2 = tk_to_qiskit(tket_qc)
+
+    assert type(qc_2.global_phase) == ParameterExpression
+
+
 def test_classical_barrier_error() -> None:
     c = Circuit(1, 1)
     c.add_barrier([0], [0])
@@ -398,24 +430,17 @@ def test_conditions() -> None:
 
 
 def test_condition_errors() -> None:
-    with pytest.raises(Exception) as errorinfo:
-        c = Circuit(2, 2)
-        c.X(0, condition_bits=[0], condition_value=1)
-        tk_to_qiskit(c)
-    assert "OpenQASM conditions must be an entire register" in str(errorinfo.value)
     with pytest.raises(Exception) as errorinfo:
         c = Circuit(2, 2)
         b = c.add_c_register("b", 2)
         c.X(Qubit(0), condition_bits=[b[0], Bit(0)], condition_value=1)
         tk_to_qiskit(c)
-    assert "OpenQASM conditions can only use a single register" in str(errorinfo.value)
+    assert "Conditions can only use a single register" in str(errorinfo.value)
     with pytest.raises(Exception) as errorinfo:
         c = Circuit(2, 2)
         c.X(0, condition_bits=[1, 0], condition_value=1)
         tk_to_qiskit(c)
-    assert "OpenQASM conditions must be an entire register in order" in str(
-        errorinfo.value
-    )
+    assert "Conditions must be an entire register in order" in str(errorinfo.value)
 
 
 def test_correction() -> None:
@@ -857,6 +882,26 @@ def test_ccx_conversion() -> None:
     )
 
 
+def test_conditional_conversion() -> None:
+    c = Circuit(1, 2, "conditional_circ")
+    c.X(0, condition_bits=[0], condition_value=1)
+
+    c_qiskit = tk_to_qiskit(c)
+    c_tket = qiskit_to_tk(c_qiskit)
+
+    assert c_tket.to_dict() == c.to_dict()
+
+
+def test_conditional_conversion_2() -> None:
+    c = Circuit(1, 2, "conditional_circ_2")
+    c.X(0, condition_bits=[1], condition_value=1)
+
+    c_qiskit = tk_to_qiskit(c)
+    c_tket = qiskit_to_tk(c_qiskit)
+
+    assert c_tket.to_dict() == c.to_dict()
+
+
 # https://github.com/CQCL/pytket-qiskit/issues/100
 def test_state_prep_conversion_array_or_list() -> None:
     # State prep with list of real amplitudes