✨ Add error correction module with Shor and Steane logical circuit transpilers

.gitignore

@@ -316,3 +316,6 @@ ehthumbs.db
 
 # setuptools_scm
 src/**/_version.py
+.idea/
+# Test Output
+tests/circuit_drawings/*

CHANGELOG.md

@@ -21,6 +21,13 @@ that minor releases may include breaking changes.
 - ✨ Add Iterative Quantum Phase Estimation (IQPE) benchmark ([#925])
   ([**@johanneswittmann9**])
 
+### Changed
+
+- ⚡ Improve `ShorTranspiler` to transpile input circuits to the target basis
+  using a circuit-wide compilation pass instead of individual manual gate
+  decomposition, representing logical T and T-dagger gates via opaque magic
+  state injection gadgets.
+
 ### Fixed
 
 - 🐛 Seed `GenericBackendV2` used by `get_target_for_gateset` to ensure

pyproject.toml

@@ -22,7 +22,8 @@ dynamic = ["version"]
 dependencies = [
     # Qiskit 1.3.2 contains some fixes for exporting OpenQASM 3 files
     # Qiskit 2.0.0 fixes the SolovayKitaev transpiler for mid-circuit measurements
-    "qiskit[qasm3-import]>=2.0.0",
+    # Qiskit 2.4.0 fixes the transpilation to Clifford+T basis
+    "qiskit[qasm3-import]>=2.4.0",
     "networkx>=2.8.8",
     "numpy>=1.22",
     "numpy>=1.24; python_version >= '3.11'",
@@ -249,6 +250,7 @@ aer = "aer"
 fom = "fom"
 bench = "bench"
 benchs = "benchs"
+ket = "ket"
 
 
 [tool.repo-review.ignore]

src/mqt/bench/benchmark_generation.py

@@ -22,6 +22,9 @@
 from qiskit.transpiler import Layout, Target
 from typing_extensions import assert_never
 
+from .error_correction.shor_transpiler import ShorTranspiler
+from .error_correction.steane_transpiler import SteaneTranspiler
+
 if sys.version_info >= (3, 11):
     from typing import Unpack
 else:
@@ -198,6 +201,7 @@ def get_benchmark_alg(
 def get_benchmark_alg(
     benchmark: str | QuantumCircuit,
     circuit_size: int | None = None,
+    encoding: str = "",
     *,
     generate_mirror_circuit: bool = False,
     random_parameters: bool = True,
@@ -208,16 +212,33 @@ def get_benchmark_alg(
     Arguments:
         benchmark: QuantumCircuit or name of the benchmark to be generated
         circuit_size: Input for the benchmark creation, in most cases this is equal to the qubit number
+        encoding: Error correction code to be used, can be any of {"", "steane", "shor"}.
         generate_mirror_circuit: If True, generates the mirror version (U @ U.inverse()) of the benchmark.
         random_parameters: If True, assigns random parameters to the circuit's parameters if they exist.
         kwargs: Additional keyword arguments passed to the circuit creation.
 
     Returns:
         Qiskit::QuantumCircuit representing the raw benchmark circuit without any hardware-specific compilation or mapping.
     """
+    valid_encodings = {"", "shor", "steane"}
+    if encoding not in valid_encodings:
+        msg = f"Invalid `encoding` '{encoding}'. Must be one of {valid_encodings}."
+        raise ValueError(msg)
+
     qc = _get_circuit(benchmark, circuit_size, random_parameters, **kwargs)
+    # Todo: Make it combined with error code
     if generate_mirror_circuit:
-        return _create_mirror_circuit(qc, inplace=True)
+        qc = _create_mirror_circuit(qc, inplace=True)
+
+    if encoding == "shor":
+        transpiler = ShorTranspiler(qc, add_syndromes=True)
+        transpiler.transpile()
+        qc = transpiler.transpiled_qc
+    if encoding == "steane":
+        transpiler = SteaneTranspiler(qc, add_syndromes=True)
+        transpiler.transpile()
+        qc = transpiler.transpiled_qc
+
     return qc
 
 
@@ -478,6 +499,7 @@ def get_benchmark(
     circuit_size: int,
     target: Target | None = None,
     opt_level: int = 2,
+    encoding: str = "",
     *,
     generate_mirror_circuit: bool = False,
     random_parameters: bool = True,
@@ -492,6 +514,7 @@ def get_benchmark(
     circuit_size: None,
     target: Target | None = None,
     opt_level: int = 2,
+    encoding: str = "",
     *,
     generate_mirror_circuit: bool = False,
     random_parameters: bool = True,
@@ -506,6 +529,7 @@ def get_benchmark(
     circuit_size: int | None = None,
     target: Target | None = None,
     opt_level: int = 2,
+    encoding: str = "",
     *,
     generate_mirror_circuit: bool = False,
     random_parameters: bool = True,
@@ -519,6 +543,7 @@ def get_benchmark(
     circuit_size: int | None = None,
     target: Target | None = None,
     opt_level: int = 2,
+    encoding: str = "",
     *,
     generate_mirror_circuit: bool = False,
     random_parameters: bool = True,
@@ -533,6 +558,7 @@ def get_benchmark(
         target: `~qiskit.transpiler.target.Target` for the benchmark generation
                 (only used for "nativegates" and "mapped" level)
         opt_level: Optimization level to be used by the transpiler.
+        encoding: Error correction code to be used, can be any of {"", "steane", "shor"}.
         generate_mirror_circuit: If True, generates the mirror version (U @ U.inverse()) of the benchmark.
         random_parameters: If True, assigns random parameters to the circuit's parameters if they exist.
         kwargs: Additional keyword arguments passed to the circuit creation.
@@ -546,6 +572,7 @@ def get_benchmark(
             circuit_size=circuit_size,
             generate_mirror_circuit=generate_mirror_circuit,
             random_parameters=random_parameters,
+            encoding=encoding,
             **kwargs,
         )
 

src/mqt/bench/benchmarks/seven_qubit_steane_code.py

@@ -13,127 +13,14 @@
 from qiskit import ClassicalRegister
 from qiskit.circuit import AncillaRegister, QuantumCircuit, QuantumRegister
 
-from ._registry import register_benchmark
-
-
-def _get_seven_qubit_steane_code_encoding_circuit() -> QuantumCircuit:
-    """Create the 7-qubit Steane code encoding circuit.
-
-    Encodes qubit 0 into the 7-qubit Steane code logical state:
-        - |0> -> (|0000000> + |1010101> + |0110011> + |1100110> + |0001111> + |1011010> + |0111100> + |1101001>)
-        - |1> -> (|1111111> + |0101010> + |1001100> + |0011001> + |1110000> + |0100101> + |1000011> + |0010110>).
-
-    Returns:
-        QuantumCircuit: 7-qubit encoding circuit.
-    """
-    out = QuantumCircuit(7)
-    # H
-    out.h(4)
-    out.h(5)
-    out.h(6)
-    # CNOT from 0
-    out.cx(0, 1)
-    out.cx(0, 2)
-    # CNOT from 6
-    out.cx(6, 3)
-    out.cx(6, 1)
-    out.cx(6, 0)
-    # CNOT from 5
-    out.cx(5, 3)
-    out.cx(5, 2)
-    out.cx(5, 0)
-    # CNOT from 4
-    out.cx(4, 3)
-    out.cx(4, 2)
-    out.cx(4, 1)
-    return out
-
-
-def _get_seven_qubit_steane_code_decoding_circuit() -> QuantumCircuit:
-    """Create the 7-qubit Steane code decoding circuit.
-
-    Reverses the encoding operation to extract the logical qubit back to qubit 0.
-
-    Returns:
-        QuantumCircuit: 7-qubit decoding circuit (qubit 0 is the output qubit).
-    """
-    return _get_seven_qubit_steane_code_encoding_circuit().inverse()
-
+from mqt.bench.components.steane_circuit_components import (
+    apply_seven_qubit_steane_code_correction,
+    get_seven_qubit_steane_code_decoding_circuit,
+    get_seven_qubit_steane_code_encoding_circuit,
+    get_seven_qubit_steane_code_syndrome_extraction_circuit,
+)
 
-def _get_seven_qubit_steane_code_syndrome_extraction_circuit() -> QuantumCircuit:
-    """Create the syndrome extraction circuit for the 7-qubit Steane code.
-
-    Extracts bit-flip and phase-flip syndromes using 6 ancilla qubits (3 for each type).
-
-    Bit-flip syndrome extraction:
-        Syndrome bits measure the parity of specific qubit subsets corresponding to
-        the X-stabilizer generators.
-
-    Phase-flip syndrome extraction:
-        Uses Hadamard gates to convert from Z to X basis, and control/target swapped
-        CNOTs to extract the phase-flip syndrome
-
-    Syndrome mapping: The 3-bit syndrome value (1-7) directly identifies which
-    data qubit experienced an error. Syndrome 0 indicates no error.
-
-    Returns:
-        QuantumCircuit: 13-qubit circuit (qubits 0-6 are data, 7-9 are bit-flip
-            syndrome ancillas, 10-12 are phase-flip syndrome ancillas).
-    """
-    logical_qubit, bit_flip_syndrome, phase_flip_syndrome = QuantumRegister(7), AncillaRegister(3), AncillaRegister(3)
-    out = QuantumCircuit(logical_qubit, bit_flip_syndrome, phase_flip_syndrome)
-    # Bit-flip
-    for ctrl in (0, 2, 4, 6):
-        out.cx(logical_qubit[ctrl], bit_flip_syndrome[0])
-    for ctrl in (1, 2, 5, 6):
-        out.cx(logical_qubit[ctrl], bit_flip_syndrome[1])
-    for ctrl in (3, 4, 5, 6):
-        out.cx(logical_qubit[ctrl], bit_flip_syndrome[2])
-    # Phase-flip
-    for i in range(3):
-        out.h(phase_flip_syndrome[i])
-    for targ in (0, 2, 4, 6):
-        out.cx(phase_flip_syndrome[0], logical_qubit[targ])
-    for targ in (1, 2, 5, 6):
-        out.cx(phase_flip_syndrome[1], logical_qubit[targ])
-    for targ in (3, 4, 5, 6):
-        out.cx(phase_flip_syndrome[2], logical_qubit[targ])
-    for i in range(3):
-        out.h(phase_flip_syndrome[i])
-    return out
-
-
-def _apply_seven_qubit_steane_code_correction(
-    qc: QuantumCircuit,
-    logical_qubit: QuantumRegister,
-    bit_flip_syndrome: AncillaRegister,
-    phase_flip_syndrome: AncillaRegister,
-    bit_flip_syndrome_measurement: ClassicalRegister,
-    phase_flip_syndrome_measurement: ClassicalRegister,
-) -> None:
-    """Apply error correction based on syndrome measurements.
-
-    Measures the 6 syndrome qubits and conditionally applies X/Z gates to correct
-    single-qubit errors on any of the 7 data qubits.
-
-    Arguments:
-        qc: The quantum circuit to modify.
-        logical_qubit: Register containing the 7 data qubits.
-        bit_flip_syndrome: Register containing the 3 bit-flip syndrome qubits.
-        phase_flip_syndrome: Register containing the 3 phase-flip syndrome qubits.
-        bit_flip_syndrome_measurement: Classical register for bit-flip syndrome results.
-        phase_flip_syndrome_measurement: Classical register for phase-flip syndrome results.
-    """
-    qc.measure(bit_flip_syndrome, bit_flip_syndrome_measurement)
-    qc.measure(phase_flip_syndrome, phase_flip_syndrome_measurement)
-    # Bit-flip correction: syndrome value directly indicates which qubit to correct
-    for i in range(7):
-        with qc.if_test((bit_flip_syndrome_measurement, i + 1)):
-            qc.x(logical_qubit[i])
-    # Phase-flip correction: syndrome value directly indicates which qubit to correct
-    for i in range(7):
-        with qc.if_test((phase_flip_syndrome_measurement, i + 1)):
-            qc.z(logical_qubit[i])
+from ._registry import register_benchmark
 
 
 def _create_single_logical_qubit_circuit(index: int) -> QuantumCircuit:
@@ -164,20 +51,20 @@ def _create_single_logical_qubit_circuit(index: int) -> QuantumCircuit:
     )
     # == Encoding ==
     qc.compose(
-        _get_seven_qubit_steane_code_encoding_circuit(),
+        get_seven_qubit_steane_code_encoding_circuit(),
         qubits=logical_qubit[:],
         inplace=True,
     )
     qc.barrier()
     # == Syndrome extraction ==
     qc.compose(
-        _get_seven_qubit_steane_code_syndrome_extraction_circuit(),
+        get_seven_qubit_steane_code_syndrome_extraction_circuit(),
         qubits=logical_qubit[:] + bit_flip_syndrome[:] + phase_flip_syndrome[:],
         inplace=True,
     )
     qc.barrier()
     # == Error correction ==
-    _apply_seven_qubit_steane_code_correction(
+    apply_seven_qubit_steane_code_correction(
         qc,
         logical_qubit,
         bit_flip_syndrome,
@@ -188,7 +75,7 @@ def _create_single_logical_qubit_circuit(index: int) -> QuantumCircuit:
     qc.barrier()
     # == Decoding ==
     qc.compose(
-        _get_seven_qubit_steane_code_decoding_circuit(),
+        get_seven_qubit_steane_code_decoding_circuit(),
         qubits=logical_qubit[:],
         inplace=True,
     )