Follow up on #12327: circuit construction in Rust (#12605)

* Follow up on #12327

also port circuit construction to rust and add a reno

* move _get_ordered_swap to Rust only

* drop redundant Ok(expect())

* proper synthesis structure

crates/accelerate/src/lib.rs

@@ -23,12 +23,12 @@ pub mod isometry;
 pub mod nlayout;
 pub mod optimize_1q_gates;
 pub mod pauli_exp_val;
-pub mod permutation;
 pub mod results;
 pub mod sabre;
 pub mod sampled_exp_val;
 pub mod sparse_pauli_op;
 pub mod stochastic_swap;
+pub mod synthesis;
 pub mod two_qubit_decompose;
 pub mod uc_gate;
 pub mod utils;

crates/accelerate/src/synthesis/mod.rs

@@ -0,0 +1,22 @@
+// This code is part of Qiskit.
+//
+// (C) Copyright IBM 2024
+//
+// This code is licensed under the Apache License, Version 2.0. You may
+// obtain a copy of this license in the LICENSE.txt file in the root directory
+// of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+//
+// Any modifications or derivative works of this code must retain this
+// copyright notice, and modified files need to carry a notice indicating
+// that they have been altered from the originals.
+
+mod permutation;
+
+use pyo3::prelude::*;
+use pyo3::wrap_pymodule;
+
+#[pymodule]
+pub fn synthesis(m: &Bound<PyModule>) -> PyResult<()> {
+    m.add_wrapped(wrap_pymodule!(permutation::permutation))?;
+    Ok(())
+}

crates/accelerate/src/synthesis/permutation/mod.rs

@@ -0,0 +1,68 @@
+// This code is part of Qiskit.
+//
+// (C) Copyright IBM 2024
+//
+// This code is licensed under the Apache License, Version 2.0. You may
+// obtain a copy of this license in the LICENSE.txt file in the root directory
+// of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+//
+// Any modifications or derivative works of this code must retain this
+// copyright notice, and modified files need to carry a notice indicating
+// that they have been altered from the originals.
+
+use numpy::PyArrayLike1;
+use smallvec::smallvec;
+
+use pyo3::prelude::*;
+use pyo3::wrap_pyfunction;
+
+use qiskit_circuit::circuit_data::CircuitData;
+use qiskit_circuit::operations::{Param, StandardGate};
+use qiskit_circuit::Qubit;
+
+mod utils;
+
+/// Checks whether an array of size N is a permutation of 0, 1, ..., N - 1.
+#[pyfunction]
+#[pyo3(signature = (pattern))]
+pub fn _validate_permutation(py: Python, pattern: PyArrayLike1<i64>) -> PyResult<PyObject> {
+    let view = pattern.as_array();
+    utils::validate_permutation(&view)?;
+    Ok(py.None())
+}
+
+/// Finds inverse of a permutation pattern.
+#[pyfunction]
+#[pyo3(signature = (pattern))]
+pub fn _inverse_pattern(py: Python, pattern: PyArrayLike1<i64>) -> PyResult<PyObject> {
+    let view = pattern.as_array();
+    let inverse_i64: Vec<i64> = utils::invert(&view).iter().map(|&x| x as i64).collect();
+    Ok(inverse_i64.to_object(py))
+}
+
+#[pyfunction]
+#[pyo3(signature = (pattern))]
+pub fn _synth_permutation_basic(py: Python, pattern: PyArrayLike1<i64>) -> PyResult<CircuitData> {
+    let view = pattern.as_array();
+    let num_qubits = view.len();
+    CircuitData::from_standard_gates(
+        py,
+        num_qubits as u32,
+        utils::get_ordered_swap(&view).iter().map(|(i, j)| {
+            (
+                StandardGate::SwapGate,
+                smallvec![],
+                smallvec![Qubit(*i as u32), Qubit(*j as u32)],
+            )
+        }),
+        Param::Float(0.0),
+    )
+}
+
+#[pymodule]
+pub fn permutation(m: &Bound<PyModule>) -> PyResult<()> {
+    m.add_function(wrap_pyfunction!(_validate_permutation, m)?)?;
+    m.add_function(wrap_pyfunction!(_inverse_pattern, m)?)?;
+    m.add_function(wrap_pyfunction!(_synth_permutation_basic, m)?)?;
+    Ok(())
+}

crates/accelerate/src/permutation.rs → crates/accelerate/src/synthesis/permutation/utils.rs

@@ -11,12 +11,11 @@
 // that they have been altered from the originals.
 
 use ndarray::{Array1, ArrayView1};
-use numpy::PyArrayLike1;
 use pyo3::exceptions::PyValueError;
 use pyo3::prelude::*;
 use std::vec::Vec;
 
-fn validate_permutation(pattern: &ArrayView1<i64>) -> PyResult<()> {
+pub fn validate_permutation(pattern: &ArrayView1<i64>) -> PyResult<()> {
     let n = pattern.len();
     let mut seen: Vec<bool> = vec![false; n];
 
@@ -47,15 +46,24 @@ fn validate_permutation(pattern: &ArrayView1<i64>) -> PyResult<()> {
     Ok(())
 }
 
-fn invert(pattern: &ArrayView1<i64>) -> Array1<usize> {
+pub fn invert(pattern: &ArrayView1<i64>) -> Array1<usize> {
     let mut inverse: Array1<usize> = Array1::zeros(pattern.len());
     pattern.iter().enumerate().for_each(|(ii, &jj)| {
         inverse[jj as usize] = ii;
     });
     inverse
 }
 
-fn get_ordered_swap(pattern: &ArrayView1<i64>) -> Vec<(i64, i64)> {
+/// Sorts the input permutation by iterating through the permutation list
+/// and putting each element to its correct position via a SWAP (if it's not
+/// at the correct position already). If ``n`` is the length of the input
+/// permutation, this requires at most ``n`` SWAPs.
+///
+/// More precisely, if the input permutation is a cycle of length ``m``,
+/// then this creates a quantum circuit with ``m-1`` SWAPs (and of depth ``m-1``);
+/// if the input  permutation consists of several disjoint cycles, then each cycle
+/// is essentially treated independently.
+pub fn get_ordered_swap(pattern: &ArrayView1<i64>) -> Vec<(i64, i64)> {
     let mut permutation: Vec<usize> = pattern.iter().map(|&x| x as usize).collect();
     let mut index_map = invert(pattern);
 
@@ -76,45 +84,3 @@ fn get_ordered_swap(pattern: &ArrayView1<i64>) -> Vec<(i64, i64)> {
     swaps[..].reverse();
     swaps
 }
-
-/// Checks whether an array of size N is a permutation of 0, 1, ..., N - 1.
-#[pyfunction]
-#[pyo3(signature = (pattern))]
-fn _validate_permutation(py: Python, pattern: PyArrayLike1<i64>) -> PyResult<PyObject> {
-    let view = pattern.as_array();
-    validate_permutation(&view)?;
-    Ok(py.None())
-}
-
-/// Finds inverse of a permutation pattern.
-#[pyfunction]
-#[pyo3(signature = (pattern))]
-fn _inverse_pattern(py: Python, pattern: PyArrayLike1<i64>) -> PyResult<PyObject> {
-    let view = pattern.as_array();
-    let inverse_i64: Vec<i64> = invert(&view).iter().map(|&x| x as i64).collect();
-    Ok(inverse_i64.to_object(py))
-}
-
-/// Sorts the input permutation by iterating through the permutation list
-/// and putting each element to its correct position via a SWAP (if it's not
-/// at the correct position already). If ``n`` is the length of the input
-/// permutation, this requires at most ``n`` SWAPs.
-///
-/// More precisely, if the input permutation is a cycle of length ``m``,
-/// then this creates a quantum circuit with ``m-1`` SWAPs (and of depth ``m-1``);
-/// if the input  permutation consists of several disjoint cycles, then each cycle
-/// is essentially treated independently.
-#[pyfunction]
-#[pyo3(signature = (permutation_in))]
-fn _get_ordered_swap(py: Python, permutation_in: PyArrayLike1<i64>) -> PyResult<PyObject> {
-    let view = permutation_in.as_array();
-    Ok(get_ordered_swap(&view).to_object(py))
-}
-
-#[pymodule]
-pub fn permutation(m: &Bound<PyModule>) -> PyResult<()> {
-    m.add_function(wrap_pyfunction!(_validate_permutation, m)?)?;
-    m.add_function(wrap_pyfunction!(_inverse_pattern, m)?)?;
-    m.add_function(wrap_pyfunction!(_get_ordered_swap, m)?)?;
-    Ok(())
-}

crates/pyext/src/lib.rs

@@ -17,10 +17,10 @@ use qiskit_accelerate::{
     convert_2q_block_matrix::convert_2q_block_matrix, dense_layout::dense_layout,
     error_map::error_map, euler_one_qubit_decomposer::euler_one_qubit_decomposer,
     isometry::isometry, nlayout::nlayout, optimize_1q_gates::optimize_1q_gates,
-    pauli_exp_val::pauli_expval, permutation::permutation, results::results, sabre::sabre,
-    sampled_exp_val::sampled_exp_val, sparse_pauli_op::sparse_pauli_op,
-    stochastic_swap::stochastic_swap, two_qubit_decompose::two_qubit_decompose, uc_gate::uc_gate,
-    utils::utils, vf2_layout::vf2_layout,
+    pauli_exp_val::pauli_expval, results::results, sabre::sabre, sampled_exp_val::sampled_exp_val,
+    sparse_pauli_op::sparse_pauli_op, stochastic_swap::stochastic_swap, synthesis::synthesis,
+    two_qubit_decompose::two_qubit_decompose, uc_gate::uc_gate, utils::utils,
+    vf2_layout::vf2_layout,
 };
 
 #[pymodule]
@@ -36,7 +36,7 @@ fn _accelerate(m: &Bound<PyModule>) -> PyResult<()> {
     m.add_wrapped(wrap_pymodule!(nlayout))?;
     m.add_wrapped(wrap_pymodule!(optimize_1q_gates))?;
     m.add_wrapped(wrap_pymodule!(pauli_expval))?;
-    m.add_wrapped(wrap_pymodule!(permutation))?;
+    m.add_wrapped(wrap_pymodule!(synthesis))?;
     m.add_wrapped(wrap_pymodule!(results))?;
     m.add_wrapped(wrap_pymodule!(sabre))?;
     m.add_wrapped(wrap_pymodule!(sampled_exp_val))?;

qiskit/__init__.py

@@ -80,7 +80,7 @@
 sys.modules["qiskit._accelerate.stochastic_swap"] = _accelerate.stochastic_swap
 sys.modules["qiskit._accelerate.two_qubit_decompose"] = _accelerate.two_qubit_decompose
 sys.modules["qiskit._accelerate.vf2_layout"] = _accelerate.vf2_layout
-sys.modules["qiskit._accelerate.permutation"] = _accelerate.permutation
+sys.modules["qiskit._accelerate.synthesis.permutation"] = _accelerate.synthesis.permutation
 
 from qiskit.exceptions import QiskitError, MissingOptionalLibraryError
 

qiskit/circuit/library/generalized_gates/permutation.py

@@ -80,15 +80,13 @@ def __init__(
 
         name = "permutation_" + np.array_str(pattern).replace(" ", ",")
 
-        circuit = QuantumCircuit(num_qubits, name=name)
-
         super().__init__(num_qubits, name=name)
 
         # pylint: disable=cyclic-import
-        from qiskit.synthesis.permutation.permutation_utils import _get_ordered_swap
+        from qiskit.synthesis.permutation import synth_permutation_basic
 
-        for i, j in _get_ordered_swap(pattern):
-            circuit.swap(i, j)
+        circuit = synth_permutation_basic(pattern)
+        circuit.name = name
 
         all_qubits = self.qubits
         self.append(circuit.to_gate(), all_qubits)
@@ -184,10 +182,11 @@ def inverse(self, annotated: bool = False):
 
     def _qasm2_decomposition(self):
         # pylint: disable=cyclic-import
-        from qiskit.synthesis.permutation.permutation_utils import _get_ordered_swap
+        from qiskit.synthesis.permutation import synth_permutation_basic
 
         name = f"permutation__{'_'.join(str(n) for n in self.pattern)}_"
-        out = QuantumCircuit(self.num_qubits, name=name)
-        for i, j in _get_ordered_swap(self.pattern):
-            out.swap(i, j)
+
+        out = synth_permutation_basic(self.pattern)
+        out.name = name
+
         return out.to_gate()

qiskit/synthesis/permutation/permutation_full.py

@@ -16,8 +16,8 @@
 
 import numpy as np
 from qiskit.circuit.quantumcircuit import QuantumCircuit
+from qiskit._accelerate.synthesis.permutation import _synth_permutation_basic
 from .permutation_utils import (
-    _get_ordered_swap,
     _inverse_pattern,
     _pattern_to_cycles,
     _decompose_cycles,
@@ -44,17 +44,7 @@ def synth_permutation_basic(pattern: list[int] | np.ndarray[int]) -> QuantumCirc
     Returns:
         The synthesized quantum circuit.
     """
-    # This is the very original Qiskit algorithm for synthesizing permutations.
-
-    num_qubits = len(pattern)
-    qc = QuantumCircuit(num_qubits)
-
-    swaps = _get_ordered_swap(pattern)
-
-    for swap in swaps:
-        qc.swap(swap[0], swap[1])
-
-    return qc
+    return QuantumCircuit._from_circuit_data(_synth_permutation_basic(pattern))
 
 
 def synth_permutation_acg(pattern: list[int] | np.ndarray[int]) -> QuantumCircuit:

qiskit/synthesis/permutation/permutation_utils.py

@@ -13,9 +13,8 @@
 """Utility functions for handling permutations."""
 
 # pylint: disable=unused-import
-from qiskit._accelerate.permutation import (
+from qiskit._accelerate.synthesis.permutation import (
     _inverse_pattern,
-    _get_ordered_swap,
     _validate_permutation,
 )
 

releasenotes/notes/oxidize-permbasic-be27578187ac472f.yaml

@@ -0,0 +1,4 @@
+---
+upgrade_synthesis:
+  - |
+    Port :func:`.synth_permutation_basic`, used to synthesize qubit permutations, to Rust.

test/python/synthesis/test_permutation_synthesis.py

@@ -27,7 +27,6 @@
 )
 from qiskit.synthesis.permutation.permutation_utils import (
     _inverse_pattern,
-    _get_ordered_swap,
     _validate_permutation,
 )
 from test import QiskitTestCase  # pylint: disable=wrong-import-order
@@ -47,19 +46,6 @@ def test_inverse_pattern(self, width):
             for ii, jj in enumerate(pattern):
                 self.assertTrue(inverse[jj] == ii)
 
-    @data(4, 5, 10, 15, 20)
-    def test_get_ordered_swap(self, width):
-        """Test _get_ordered_swap function produces correct swap list."""
-        np.random.seed(1)
-        for _ in range(5):
-            pattern = np.random.permutation(width)
-            swap_list = _get_ordered_swap(pattern)
-            output = list(range(width))
-            for i, j in swap_list:
-                output[i], output[j] = output[j], output[i]
-            self.assertTrue(np.array_equal(pattern, output))
-            self.assertLess(len(swap_list), width)
-
     @data(10, 20)
     def test_invalid_permutations(self, width):
         """Check that _validate_permutation raises exceptions when the