🐛 Support BQSKit conversion of IQM's native r gate

CHANGELOG.md

@@ -11,6 +11,7 @@ This project adheres to [Semantic Versioning], with the exception that minor rel
 
 ### Changed
 
+- 🐛 Support BQSKit conversion of IQM's native `r` gate ([#679]) ([**@flowerthrower**])
 - 🔧 Replace `mypy` with `ty` ([#572]) ([**@denialhaag**])
 - 🐛 Fix instruction duration unit in estimated success probability calculation ([#445]) ([**@Shaobo-Zhou**])
 - ✨ Remove support for custom names of trained models ([#489]) ([**@bachase**])
@@ -46,6 +47,7 @@ _📚 Refer to the [GitHub Release Notes](https://github.com/munich-quantum-tool
 
 <!-- PR links -->
 
+[#679]: https://github.com/munich-quantum-toolkit/predictor/pull/679
 [#572]: https://github.com/munich-quantum-toolkit/predictor/pull/572
 [#489]: https://github.com/munich-quantum-toolkit/predictor/pull/489
 [#445]: https://github.com/munich-quantum-toolkit/predictor/pull/445

src/mqt/predictor/rl/parsing.py

@@ -11,22 +11,30 @@
 from __future__ import annotations
 
 import operator
+import re
 from functools import cache
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, cast
 
 from bqskit.ir import gates
+from bqskit.ir.lang.qasm2 import OPENQASM2Language
 from pytket import Qubit
 from pytket.circuit import Node
 from pytket.placement import place_with_map
-from qiskit.circuit import QuantumRegister
+from qiskit import qasm2
+from qiskit.circuit import QuantumCircuit, QuantumRegister
+from qiskit.circuit.library import RGate
 from qiskit.converters import circuit_to_dag, dag_to_circuit
 from qiskit.transpiler import Layout, TranspileLayout
 from qiskit.transpiler.passes import ApplyLayout
 
 if TYPE_CHECKING:
+    from collections.abc import Callable
+
+    from bqskit.ir import Circuit as BqskitCircuit
     from bqskit.ir import Gate
-    from pytket import Circuit
+    from pytket import Circuit as TketCircuit
     from qiskit import QuantumCircuit
+    from qiskit.circuit import Instruction
     from qiskit.transpiler import Target
 
 
@@ -87,7 +95,7 @@ class PreProcessTKETRoutingAfterQiskitLayout:
 
     """
 
-    def apply(self, circuit: Circuit) -> None:
+    def apply(self, circuit: TketCircuit) -> None:
         """Applies the pre-processing step to route a circuit with tket after a Qiskit Layout pass has been applied."""
         mapping = {Qubit(i): Node(i) for i in range(circuit.n_qubits)}
         place_with_map(circuit=circuit, qmap=mapping)
@@ -121,6 +129,7 @@ def get_bqskit_native_gates(device: Target) -> list[Gate]:
         "rx": gates.RXGate(),
         "ry": gates.RYGate(),
         "rz": gates.RZGate(),
+        "r": gates.U1qGate(),
         "u1": gates.U1Gate(),
         "u2": gates.U2Gate(),
         "u3": gates.U3Gate(),
@@ -178,7 +187,37 @@ def get_bqskit_native_gates(device: Target) -> list[Gate]:
     return native_gates
 
 
-def final_layout_pytket_to_qiskit(pytket_circuit: Circuit, qiskit_circuit: QuantumCircuit) -> Layout:
+def bqskit_to_qiskit(circuit: BqskitCircuit) -> QuantumCircuit:
+    """Convert a BQSKit Circuit to Qiskit's QuantumCircuit.
+
+    This function extends BQSKit's built-in conversion by adding support for
+    IQM's native 'r' gate. BQSKit represents this as U1qGate, which is converted
+    to Qiskit's RGate by rewriting the OpenQASM 2 output.
+
+    Args:
+        circuit: The BQSKit circuit to convert.
+
+    Returns:
+        The equivalent Qiskit QuantumCircuit with 'r' gates properly mapped.
+    """
+    qasm = OPENQASM2Language().encode(circuit)
+    qasm = re.sub(r"\bU1q\(", "r(", qasm)
+
+    def r_gate(theta: float, phi: float) -> RGate:
+        return RGate(theta, phi)
+
+    r_gate_constructor = cast("Callable[[tuple[int | float, ...]], Instruction]", r_gate)
+
+    return qasm2.loads(
+        qasm,
+        custom_instructions=(
+            *qasm2.LEGACY_CUSTOM_INSTRUCTIONS,
+            qasm2.CustomInstruction("r", 2, 1, r_gate_constructor, builtin=True),
+        ),
+    )
+
+
+def final_layout_pytket_to_qiskit(pytket_circuit: TketCircuit, qiskit_circuit: QuantumCircuit) -> Layout:
     """Converts a final layout from pytket to qiskit."""
     pytket_layout = pytket_circuit.qubit_readout
     size_circuit = pytket_circuit.n_qubits

src/mqt/predictor/rl/predictorenv.py

@@ -32,7 +32,7 @@
 from typing import cast
 
 import numpy as np
-from bqskit.ext import bqskit_to_qiskit, qiskit_to_bqskit
+from bqskit.ext import qiskit_to_bqskit
 from gymnasium import Env
 from gymnasium.spaces import Box, Dict, Discrete
 from joblib import load
@@ -56,6 +56,7 @@
 from mqt.predictor.rl.helper import create_feature_dict, get_path_training_circuits, get_state_sample
 from mqt.predictor.rl.parsing import (
     PreProcessTKETRoutingAfterQiskitLayout,
+    bqskit_to_qiskit,
     final_layout_bqskit_to_qiskit,
     final_layout_pytket_to_qiskit,
     postprocess_vf2postlayout,

tests/compilation/test_helper_rl.py

@@ -14,6 +14,7 @@
 from typing import TYPE_CHECKING, cast
 
 import numpy as np
+from bqskit.ir import Circuit, gates
 from mqt.bench import BenchmarkLevel, get_benchmark
 from mqt.bench.targets import get_device
 from qiskit import transpile
@@ -22,7 +23,7 @@
 
 from mqt.predictor.rl.actions import PassType, get_actions_by_pass_type
 from mqt.predictor.rl.helper import create_feature_dict, get_path_trained_model, get_path_training_circuits
-from mqt.predictor.rl.parsing import postprocess_vf2postlayout
+from mqt.predictor.rl.parsing import bqskit_to_qiskit, get_bqskit_native_gates, postprocess_vf2postlayout
 
 if TYPE_CHECKING:
     from collections.abc import Callable
@@ -53,6 +54,24 @@ def test_get_path_training_circuits() -> None:
     assert isinstance(path, Path)
 
 
+def test_get_bqskit_native_gates_supports_iqm_r_gate() -> None:
+    """Test that IQM's native RGate is represented in BQSKit."""
+    native_gates = get_bqskit_native_gates(get_device("iqm_crystal_20"))
+
+    assert any(isinstance(gate, gates.U1qGate) for gate in native_gates)
+
+
+def test_bqskit_to_qiskit_converts_u1q_to_r_gate() -> None:
+    """Test that BQSKit's U1qGate is converted to Qiskit's RGate."""
+    circuit = Circuit(1)
+    circuit.append_gate(gates.U1qGate(), [0], [0.1, 0.2])
+
+    qc = bqskit_to_qiskit(circuit)
+
+    assert qc.data[0].operation.name == "r"
+    assert qc.data[0].operation.params == [0.1, 0.2]
+
+
 def test_vf2_layout_and_postlayout() -> None:
     """Test the VF2Layout and VF2PostLayout passes."""
     qc = get_benchmark("ghz", BenchmarkLevel.ALG, 3)

tests/compilation/test_integration_further_SDKs.py

@@ -14,7 +14,7 @@
 from typing import TYPE_CHECKING, cast
 
 import pytest
-from bqskit.ext import bqskit_to_qiskit, qiskit_to_bqskit
+from bqskit.ext import qiskit_to_bqskit
 from bqskit.ir.circuit import Circuit
 from mqt.bench.targets import get_available_device_names, get_device
 from pytket.circuit import Qubit
@@ -26,6 +26,7 @@
 
 from mqt.predictor.rl.actions import CompilationOrigin, PassType, get_actions_by_pass_type
 from mqt.predictor.rl.parsing import (
+    bqskit_to_qiskit,
     final_layout_bqskit_to_qiskit,
     final_layout_pytket_to_qiskit,
 )
@@ -83,22 +84,22 @@ def test_bqskit_synthesis_action(device: Target, available_actions_dict: dict[Pa
     qc.h(0)
     qc.cx(0, 1)
 
-    check_nat_gates = GatesInBasis(target=device)
+    check_nat_gates = GatesInBasis(basis_gates=device.operation_names)
     check_nat_gates(qc)
     assert not check_nat_gates.property_set["all_gates_in_basis"]
 
     factory = cast("Callable[[Target], Callable[[Circuit], Circuit]]", action_bqskit_synthesis_action.transpile_pass)
     lambda_ = factory(device)
     bqskit_qc = qiskit_to_bqskit(qc)
-    if "rigetti" in device.description or "ionq" in device.description or "iqm" in device.description:
+    if "rigetti" in device.description or "ionq" in device.description:
         with pytest.raises(ValueError, match=re.escape("not supported in BQSKIT")):
             bqskit_qc_compiled = lambda_(bqskit_qc)
         return
     bqskit_qc_compiled = lambda_(bqskit_qc)
     assert isinstance(bqskit_qc_compiled, Circuit)
     native_gates_qc = bqskit_to_qiskit(bqskit_qc_compiled)
 
-    check_nat_gates = GatesInBasis(target=device)
+    check_nat_gates = GatesInBasis(basis_gates=device.operation_names)
     check_nat_gates(native_gates_qc)
     only_nat_gates = check_nat_gates.property_set["all_gates_in_basis"]
     assert only_nat_gates