Replacing Graphix transpiler with graphix-jcz-transpiler

CHANGELOG.md

@@ -11,7 +11,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - #476: Introduced new methods `OpenGraph.extract_circuit`, `CliffordMap.to_tableau` and new function `graphix.circ_ext.compilation.cm_berg_pass`. Circuit extraction can be done natively in Graphix.
 
-- #545: Added an amplitude damping noise model. Introduces `amplitude_damping_channel` / `two_qubit_amplitude_damping_channel`, the `AmplitudeDampingNoise` / `TwoQubitAmplitudeDampingNoise` noise elements, and `AmplitudeDampingNoiseModel`.
+- #484: J & CZ transpilation.
+  - Replaced `Circuit.transpile()` with a new approach based decomposing circuits into J & CZ gates.
+  - Added `Circuit.transpile_to_causal_flow()` to produce `CausalFlow` using the same decomposition.
+  - Added `instruction.J` class.
+  - Added `Circuit.transpile_j_to_rzh()` method to prepare circuits with J gates for export to OpenQASM.
+  - Added `transpile` argument to `qasm3_exporter.circuit_to_qasm3` and `qasm3_exporter.circuit_to_qasm3_lines`, which defaults to true and applies `Circuit.transpile_j_to_rzh` and `Circuit.transpile_measurements_to_z_axis` methods.
+  - The transpiler now returns `TranspiledPattern` or `TranspiledFlow`, instead of `TranspileResult`.
 
 - #490: Introduced new `Instruction` and `Command` namespace classes for instruction and command instantiation.
 
@@ -27,6 +33,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - #524: Added `Statevec.draw` and `DensityMatrix.draw` methods (and the underlying `statevec_to_str` and `density_matrix_to_str` functions) for pretty-printing states and density matrices in ASCII, Unicode, and LaTeX.
 
+- #545: Added an amplitude damping noise model. Introduces `amplitude_damping_channel` / `two_qubit_amplitude_damping_channel`, the `AmplitudeDampingNoise` / `TwoQubitAmplitudeDampingNoise` noise elements, and `AmplitudeDampingNoiseModel`.
+
 ### Fixed
 
 - #454, #481: Ensure `Pattern.minimize_space` only reduces max-space and does not increase it.
@@ -53,6 +61,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - #454, #481: New space minimization API that allows users to select or define custom heuristics.
 
+- #484: The dense back‑ends now perform the finalisation step by reordering the output qubits with a new `permute` method, replacing the old `sort_qubits`.
+
 - #490: Exposed more common classes and methods to top level `__init__.py`.
   - Renamed `Instruction`, `InstructionWithoutRZZ` and `Command` to `InstructionType`, `InstructionTypeWithoutRZZ` and `CommandType` respectively.
   - Moved `InstructionType`, `InstructionTypeWithoutRZZ`, `CommandType`, `Correction` and `CommandOrNoise` to `TYPE_CHECKING` blocks.

docs/source/generator.rst

@@ -16,6 +16,8 @@ Pattern Generation
 
     .. automethod:: simulate_statevector
 
+    .. automethod:: cz
+
     .. automethod:: cnot
 
     .. automethod:: h
@@ -34,10 +36,14 @@ Pattern Generation
 
     .. automethod:: rz
 
+    .. automethod:: j
+
     .. automethod:: ccx
 
     .. automethod:: m
 
-.. autoclass:: TranspileResult
+.. autoclass:: TranspiledPattern
+
+.. autoclass:: TranspiledFlow
 
 .. autoclass:: SimulateResult

examples/deutsch_jozsa.py

@@ -73,6 +73,7 @@
 # %%
 # Now we preprocess all Pauli measurements, which requires that we move inputs to N commands
 
+pattern = pattern.infer_pauli_measurements()
 pattern.remove_pauli_measurements()
 print(
     pattern.to_ascii(

examples/ghz_with_tn.py

@@ -16,7 +16,7 @@
 
 from graphix import Circuit
 
-n = 100
+n = 50
 print(f"{n}-qubit GHZ state generation")
 circuit = Circuit(n)
 

examples/mbqc_vqe.py

@@ -92,7 +92,9 @@ def build_mbqc_pattern(self, params: Iterable[ParameterizedAngle]) -> Pattern:
         pattern = circuit.transpile().pattern
         pattern.standardize()
         pattern.shift_signals()
-        pattern.remove_pauli_measurements()  # Perform Pauli measurements
+        pattern = pattern.infer_pauli_measurements()
+        pattern.remove_pauli_measurements()
+        pattern.minimize_space()
         return pattern
 
     # %%
@@ -155,7 +157,7 @@ def cost_function(params: Iterable[float]) -> float:
 # %%
 # Perform the optimization using COBYLA
 def compute() -> OptimizeResult:
-    return minimize(cost_function, initial_params, method="COBYLA", options={"maxiter": 100})
+    return minimize(cost_function, initial_params, method="COBYLA", options={"maxiter": 20})
 
 
 result = compute()
@@ -172,9 +174,9 @@ def compute() -> OptimizeResult:
 # Compare performances between using parameterized circuits (with placeholders) or not
 
 mbqc_vqe = MBQCVQEWithPlaceholders(n_qubits, hamiltonian)
-time_with_placeholders = timeit(compute, number=2)
+time_with_placeholders = timeit(compute, number=1)
 print(f"Time with placeholders: {time_with_placeholders}")
 
 mbqc_vqe = MBQCVQE(n_qubits, hamiltonian)
-time_without_placeholders = timeit(compute, number=2)
+time_without_placeholders = timeit(compute, number=1)
 print(f"Time without placeholders: {time_without_placeholders}")

examples/qaoa.py

@@ -40,6 +40,7 @@
 # %%
 # perform Pauli measurements and plot the new (minimal) graph to perform the same quantum computation
 
+pattern = pattern.infer_pauli_measurements()
 pattern.remove_pauli_measurements()
 pattern.draw(flow_from_pattern=False)
 

examples/qft_with_tn.py

@@ -67,6 +67,7 @@ def qft(circuit: Circuit, n: int) -> None:
 # Using graph rewriting rules, we can classically preprocess Pauli measurements.
 # We are currently improving the speed of this process by using rust-based graph manipulation backend.
 pattern.remove_input_nodes()
+pattern = pattern.infer_pauli_measurements()
 pattern.remove_pauli_measurements(standardize=True)
 
 

examples/tn_simulation.py

@@ -85,6 +85,7 @@ def ansatz(
 # %%
 # Optimizing by removing Pauli measurements in the pattern.
 pattern.remove_input_nodes()
+pattern = pattern.infer_pauli_measurements()
 pattern.remove_pauli_measurements(standardize=True)
 
 # %%
@@ -203,6 +204,7 @@ def cost(
     pattern.standardize()
     pattern.shift_signals()
     pattern.remove_input_nodes()
+    pattern = pattern.infer_pauli_measurements()
     pattern.remove_pauli_measurements(standardize=True)
     mbqc_tn = pattern.simulate_pattern(backend="tensornetwork", graph_prep="parallel")
     exp_val: float = 0

examples/visualization.py

@@ -37,6 +37,7 @@
 
 # %%
 # next, show the gflow:
+pattern = pattern.infer_pauli_measurements()
 pattern.remove_pauli_measurements()
 pattern.draw(flow_from_pattern=False, measurement_labels=True)
 

graphix/instruction.py

@@ -49,6 +49,7 @@ class InstructionKind(Enum):
     X = enum.auto()
     Y = enum.auto()
     Z = enum.auto()
+    J = enum.auto()
     I = enum.auto()
     M = enum.auto()
     RX = enum.auto()
@@ -290,6 +291,19 @@ def visit(self, visitor: InstructionVisitor) -> RZ:
         return RZ(visitor.visit_qubit(self.target), visitor.visit_angle(self.angle))
 
 
+@dataclass(repr=False)
+class J(_KindChecker, BaseInstruction):
+    """J circuit instruction."""
+
+    target: int
+    angle: ParameterizedAngle = field(metadata={"repr": repr_angle})
+    kind: ClassVar[Literal[InstructionKind.J]] = field(default=InstructionKind.J, init=False)
+
+    @override
+    def visit(self, visitor: InstructionVisitor) -> J:
+        return J(visitor.visit_qubit(self.target), visitor.visit_angle(self.angle))
+
+
 class InstructionWithoutRZZ:
     """Grouping of all instructions except RZZ for namespace exposure.
 
@@ -313,6 +327,7 @@ class InstructionWithoutRZZ:
     RX: TypeAlias = RX
     RY: TypeAlias = RY
     RZ: TypeAlias = RZ
+    J: TypeAlias = J
 
     def __init__(self) -> None:
         raise TypeError("InstructionWithoutRZZ is a namespace, not a class.")
@@ -334,5 +349,5 @@ def __init__(self) -> None:
 
 
 if TYPE_CHECKING:
-    InstructionTypeWithoutRZZ = CCX | CNOT | SWAP | CZ | H | S | X | Y | Z | I | M | RX | RY | RZ
+    InstructionTypeWithoutRZZ = CCX | CNOT | SWAP | CZ | H | S | X | Y | Z | I | M | RX | RY | RZ | J
     InstructionType = InstructionTypeWithoutRZZ | RZZ

graphix/ops.py

@@ -167,6 +167,35 @@ def rz(theta: ParameterizedAngle) -> npt.NDArray[np.complex128] | npt.NDArray[np
         """
         return Ops._cast_array([[exp(-1j * angle_to_rad(theta) / 2), 0], [0, exp(1j * angle_to_rad(theta) / 2)]], theta)
 
+    @overload
+    @staticmethod
+    def j(theta: Angle) -> npt.NDArray[np.complex128]: ...
+
+    @overload
+    @staticmethod
+    def j(theta: Expression) -> npt.NDArray[np.object_]: ...
+
+    @staticmethod
+    def j(theta: ParameterizedAngle) -> npt.NDArray[np.complex128] | npt.NDArray[np.object_]:
+        """J operation.
+
+        Parameters
+        ----------
+        theta : Angle | Expression
+            rotation angle in units of π
+
+        Returns
+        -------
+        operator : 2*2 np.asarray
+        """
+        return Ops._cast_array(
+            [
+                [1 / np.sqrt(2), (1 / np.sqrt(2)) * exp(1j * angle_to_rad(theta))],
+                [1 / np.sqrt(2), (-1 / np.sqrt(2)) * exp(1j * angle_to_rad(theta))],
+            ],
+            theta,
+        )
+
     @overload
     @staticmethod
     def rzz(theta: Angle) -> npt.NDArray[np.complex128]: ...