Reorganize quantum_info crate to clearly separate Python interface code

crates/accelerate/Cargo.toml

@@ -24,7 +24,7 @@ num-bigint.workspace = true
 itertools.workspace = true
 qiskit-circuit.workspace = true
 qiskit-transpiler.workspace = true
-qiskit-quantum-info.workspace = true
+qiskit-quantum-info = { workspace = true, features = ["python"]}
 qiskit-util.workspace = true
 nalgebra.workspace = true
 

crates/accelerate/src/sampled_exp_val.rs

@@ -19,8 +19,8 @@ use pyo3::prelude::*;
 use pyo3::wrap_pyfunction;
 
 use crate::pauli_exp_val::fast_sum;
+use qiskit_quantum_info::python::sparse_observable::PySparseObservable;
 use qiskit_quantum_info::sparse_observable::BitTerm;
-use qiskit_quantum_info::sparse_observable::PySparseObservable;
 use qiskit_quantum_info::sparse_observable::SparseTermView;
 use qiskit_util::complex::c64;
 

crates/cext/Cargo.toml

@@ -35,5 +35,5 @@ num-bigint.workspace = true
 num-traits.workspace = true
 
 [features]
-python_binding = ["dep:pyo3"]
+python_binding = ["dep:pyo3", "qiskit-quantum-info/python"]
 cache_pygates = ["qiskit-circuit/cache_pygates", "qiskit-transpiler/cache_pygates"]

crates/cext/src/sparse_observable.rs

@@ -1145,7 +1145,8 @@ mod py {
     use crate::pointers::mut_ptr_as_ref;
     use pyo3::exceptions::PyRuntimeError;
     use pyo3::prelude::*;
-    use qiskit_quantum_info::sparse_observable::{PySparseObservable, SparseObservable};
+    use qiskit_quantum_info::python::sparse_observable::PySparseObservable;
+    use qiskit_quantum_info::sparse_observable::SparseObservable;
     use std::sync;
 
     fn try_project_inner_observable<'a>(

crates/circuit/src/operations.rs

@@ -11,7 +11,7 @@
 // that they have been altered from the originals.
 
 use approx::relative_eq;
-use qiskit_quantum_info::sparse_pauli_op::MatrixCompressedPaulis;
+use qiskit_quantum_info::python::sparse_pauli_op::MatrixCompressedPaulis;
 use std::any::Any;
 use std::fmt::Debug;
 use std::num::NonZero;

crates/pyext/src/lib.rs

@@ -72,7 +72,7 @@ fn _accelerate(m: &Bound<PyModule>) -> PyResult<()> {
     add_submodule(m, ::qiskit_accelerate::optimize_1q_gates::optimize_1q_gates, "optimize_1q_gates")?;
     add_submodule(m, ::qiskit_transpiler::passes::optimize_1q_gates_decomposition_mod, "optimize_1q_gates_decomposition")?;
     add_submodule(m, ::qiskit_accelerate::pauli_exp_val::pauli_expval, "pauli_expval")?;
-    add_submodule(m, ::qiskit_quantum_info::pauli_lindblad_map::pauli_lindblad_map, "pauli_lindblad_map")?;
+    add_submodule(m, ::qiskit_quantum_info::python::pauli_lindblad_map::pauli_lindblad_map, "pauli_lindblad_map")?;
     add_submodule(m, ::qiskit_transpiler::passes::high_level_synthesis_mod, "high_level_synthesis")?;
     add_submodule(m, ::qiskit_transpiler::passes::remove_diagonal_gates_before_measure_mod, "remove_diagonal_gates_before_measure")?;
     add_submodule(m, ::qiskit_transpiler::passes::remove_identity_equiv_mod, "remove_identity_equiv")?;
@@ -84,8 +84,8 @@ fn _accelerate(m: &Bound<PyModule>) -> PyResult<()> {
     add_submodule(m, ::qiskit_accelerate::results::results, "results")?;
     add_submodule(m, ::qiskit_transpiler::passes::sabre::sabre, "sabre")?;
     add_submodule(m, ::qiskit_accelerate::sampled_exp_val::sampled_exp_val, "sampled_exp_val")?;
-    add_submodule(m, ::qiskit_quantum_info::sparse_observable::sparse_observable, "sparse_observable")?;
-    add_submodule(m, ::qiskit_quantum_info::sparse_pauli_op::sparse_pauli_op, "sparse_pauli_op")?;
+    add_submodule(m, ::qiskit_quantum_info::python::sparse_observable::sparse_observable, "sparse_observable")?;
+    add_submodule(m, ::qiskit_quantum_info::python::sparse_pauli_op::sparse_pauli_op, "sparse_pauli_op")?;
     add_submodule(m, ::qiskit_transpiler::passes::scheduling_mod, "scheduling")?;
     add_submodule(m, ::qiskit_synthesis::matrix::sim::unitary_sim, "unitary_sim")?;
     add_submodule(m, ::qiskit_transpiler::passes::split_2q_unitaries_mod, "split_2q_unitaries")?;

crates/qpy/src/py_methods.rs

@@ -28,7 +28,7 @@ use qiskit_circuit::imports;
 use qiskit_circuit::operations::{Operation, OperationRef, PyInstruction, PyOpKind, PyRange};
 use qiskit_circuit::packed_instruction::PackedOperation;
 use qiskit_circuit::parameter::parameter_expression::{PyParameter, PyParameterExpression};
-use qiskit_quantum_info::sparse_observable::PySparseObservable;
+use qiskit_quantum_info::python::sparse_observable::PySparseObservable;
 use uuid::Uuid;
 
 use crate::bytes::Bytes;

crates/quantum_info/src/lib.rs

@@ -12,27 +12,12 @@
 
 pub mod clifford;
 pub mod pauli_lindblad_map;
-pub mod sparse_observable;
 #[cfg(feature = "python")]
-pub mod sparse_pauli_op;
+pub mod python;
+pub mod sparse_observable;
+
 pub mod unitary_compose;
 pub mod versor_u2;
 
-#[cfg(feature = "python")] // Only currently used by python remove if needed from rust
-mod rayon_ext;
 #[cfg(test)]
 mod test;
-
-#[cfg(feature = "python")]
-use pyo3::import_exception;
-
-#[cfg(feature = "python")]
-pub(crate) mod imports {
-    use qiskit_util::py::ImportOnceCell;
-
-    pub static PAULI_TYPE: ImportOnceCell = ImportOnceCell::new("qiskit.quantum_info", "Pauli");
-    pub static PAULI_LIST_TYPE: ImportOnceCell =
-        ImportOnceCell::new("qiskit.quantum_info", "PauliList");
-}
-#[cfg(feature = "python")]
-import_exception!(qiskit.exceptions, QiskitError);

crates/quantum_info/src/pauli_lindblad_map/mod.rs

@@ -13,22 +13,3 @@
 pub mod pauli_lindblad_map_class;
 pub mod phased_qubit_sparse_pauli;
 pub mod qubit_sparse_pauli;
-
-#[cfg(feature = "python")]
-use pauli_lindblad_map_class::PyPauliLindbladMap;
-#[cfg(feature = "python")]
-use phased_qubit_sparse_pauli::{PyPhasedQubitSparsePauli, PyPhasedQubitSparsePauliList};
-#[cfg(feature = "python")]
-use pyo3::prelude::*;
-#[cfg(feature = "python")]
-use qubit_sparse_pauli::{PyQubitSparsePauli, PyQubitSparsePauliList};
-
-#[cfg(feature = "python")]
-pub fn pauli_lindblad_map(m: &Bound<PyModule>) -> PyResult<()> {
-    m.add_class::<PyPauliLindbladMap>()?;
-    m.add_class::<PyQubitSparsePauli>()?;
-    m.add_class::<PyQubitSparsePauliList>()?;
-    m.add_class::<PyPhasedQubitSparsePauli>()?;
-    m.add_class::<PyPhasedQubitSparsePauliList>()?;
-    Ok(())
-}