use crate::circuit_interfaces::{InterfaceCircuit, InterfaceGate, InterfaceGateType};
use crate::error::{Result, SimulatorError};
use crate::fermionic_simulation::{FermionicHamiltonian, FermionicOperator, FermionicString};
use crate::pauli::{PauliOperator, PauliOperatorSum, PauliString};
use crate::scirs2_integration::SciRS2Backend;
use crate::statevector::StateVectorSimulator;
use scirs2_core::ndarray::{Array1, Array2, Array4};
use scirs2_core::random::prelude::*;
use scirs2_core::Complex64;
use std::f64::consts::PI;
use super::types::{
ChemistryAnsatz, ChemistryStats, ElectronicStructureConfig, ElectronicStructureResult,
FermionMapper, HartreeFockResult, MolecularHamiltonian, Molecule, VQEOptimizer,
};
use super::quantumchemistrysimulator_type::QuantumChemistrySimulator;
impl QuantumChemistrySimulator {
pub fn new(config: ElectronicStructureConfig) -> Result<Self> {
let backend = if config.enable_second_quantization_optimization {
Some(SciRS2Backend::new())
} else {
None
};
Ok(Self {
config: config.clone(),
backend,
molecule: None,
hamiltonian: None,
hartree_fock: None,
fermion_mapper: FermionMapper::new(config.fermion_mapping, 0),
vqe_optimizer: VQEOptimizer::new(config.vqe_config.optimizer),
stats: ChemistryStats::default(),
})
}
pub(super) fn construct_molecular_hamiltonian(&mut self, molecule: &Molecule) -> Result<()> {
let num_atoms = molecule.atomic_numbers.len();
let num_orbitals = if molecule.basis_set == "STO-3G" {
num_atoms
} else {
2 * num_atoms
};
let num_electrons =
molecule.atomic_numbers.iter().sum::<u32>() as usize - molecule.charge as usize;
let one_electron_integrals = self.compute_one_electron_integrals(molecule, num_orbitals)?;
let two_electron_integrals = self.compute_two_electron_integrals(molecule, num_orbitals)?;
let nuclear_repulsion = self.compute_nuclear_repulsion(molecule)?;
let fermionic_hamiltonian = self.create_fermionic_hamiltonian(
&one_electron_integrals,
&two_electron_integrals,
num_orbitals,
)?;
self.fermion_mapper = FermionMapper::new(self.fermion_mapper.method, num_orbitals * 2);
let pauli_hamiltonian = if self.config.enable_second_quantization_optimization {
Some(self.map_to_pauli_operators(&fermionic_hamiltonian, num_orbitals)?)
} else {
None
};
self.hamiltonian = Some(MolecularHamiltonian {
one_electron_integrals,
two_electron_integrals,
nuclear_repulsion,
num_orbitals,
num_electrons,
fermionic_hamiltonian,
pauli_hamiltonian,
});
Ok(())
}
pub(super) fn create_fermionic_hamiltonian(
&self,
one_electron: &Array2<f64>,
two_electron: &Array4<f64>,
num_orbitals: usize,
) -> Result<FermionicHamiltonian> {
let mut terms = Vec::new();
for i in 0..num_orbitals {
for j in 0..num_orbitals {
if one_electron[[i, j]].abs() > 1e-12 {
let alpha_term = FermionicString {
operators: vec![
FermionicOperator::Creation(2 * i),
FermionicOperator::Annihilation(2 * j),
],
coefficient: Complex64::new(one_electron[[i, j]], 0.0),
num_modes: 2 * num_orbitals,
};
terms.push(alpha_term);
let beta_term = FermionicString {
operators: vec![
FermionicOperator::Creation(2 * i + 1),
FermionicOperator::Annihilation(2 * j + 1),
],
coefficient: Complex64::new(one_electron[[i, j]], 0.0),
num_modes: 2 * num_orbitals,
};
terms.push(beta_term);
}
}
}
for i in 0..num_orbitals {
for j in 0..num_orbitals {
for k in 0..num_orbitals {
for l in 0..num_orbitals {
if two_electron[[i, j, k, l]].abs() > 1e-12 {
let coefficient = Complex64::new(0.5 * two_electron[[i, j, k, l]], 0.0);
if i != j && k != l {
let aa_term = FermionicString {
operators: vec![
FermionicOperator::Creation(2 * i),
FermionicOperator::Creation(2 * j),
FermionicOperator::Annihilation(2 * l),
FermionicOperator::Annihilation(2 * k),
],
coefficient,
num_modes: 2 * num_orbitals,
};
terms.push(aa_term);
}
if i != j && k != l {
let bb_term = FermionicString {
operators: vec![
FermionicOperator::Creation(2 * i + 1),
FermionicOperator::Creation(2 * j + 1),
FermionicOperator::Annihilation(2 * l + 1),
FermionicOperator::Annihilation(2 * k + 1),
],
coefficient,
num_modes: 2 * num_orbitals,
};
terms.push(bb_term);
}
let ab_term = FermionicString {
operators: vec![
FermionicOperator::Creation(2 * i),
FermionicOperator::Creation(2 * j + 1),
FermionicOperator::Annihilation(2 * l + 1),
FermionicOperator::Annihilation(2 * k),
],
coefficient,
num_modes: 2 * num_orbitals,
};
terms.push(ab_term);
let ba_term = FermionicString {
operators: vec![
FermionicOperator::Creation(2 * i + 1),
FermionicOperator::Creation(2 * j),
FermionicOperator::Annihilation(2 * l),
FermionicOperator::Annihilation(2 * k + 1),
],
coefficient,
num_modes: 2 * num_orbitals,
};
terms.push(ba_term);
}
}
}
}
}
Ok(FermionicHamiltonian {
terms,
num_modes: 2 * num_orbitals,
is_hermitian: true,
})
}
pub(super) fn map_to_pauli_operators(
&self,
fermionic_ham: &FermionicHamiltonian,
num_orbitals: usize,
) -> Result<PauliOperatorSum> {
let mut pauli_terms = Vec::new();
for fermionic_term in &fermionic_ham.terms {
let pauli_string = self.fermion_mapper.map_fermionic_string(fermionic_term)?;
pauli_terms.push(pauli_string);
}
let num_qubits = num_orbitals * 2;
let mut pauli_sum = PauliOperatorSum::new(num_qubits);
for term in pauli_terms {
pauli_sum.add_term(term)?;
}
Ok(pauli_sum)
}
pub(super) fn diagonalize_fock_matrix(
&self,
fock: &Array2<f64>,
) -> Result<(Array1<f64>, Array2<f64>)> {
if let Some(ref _backend) = self.backend {
use crate::scirs2_integration::{Matrix, MemoryPool, LAPACK};
let complex_fock: Array2<Complex64> = fock.mapv(|x| Complex64::new(x, 0.0));
let pool = MemoryPool::new();
let scirs2_matrix = Matrix::from_array2(&complex_fock.view(), &pool).map_err(|e| {
SimulatorError::ComputationError(format!("Failed to create SciRS2 matrix: {e}"))
})?;
let eig_result = LAPACK::eig(&scirs2_matrix).map_err(|e| {
SimulatorError::ComputationError(format!("Eigenvalue decomposition failed: {e}"))
})?;
let eigenvalues_complex = eig_result.to_array1().map_err(|e| {
SimulatorError::ComputationError(format!("Failed to extract eigenvalues: {e}"))
})?;
let eigenvalues: Array1<f64> = eigenvalues_complex.mapv(|c| c.re);
let eigenvectors = {
#[cfg(feature = "advanced_math")]
{
let eigenvectors_complex_2d = eig_result.eigenvectors();
eigenvectors_complex_2d.mapv(|c| c.re)
}
#[cfg(not(feature = "advanced_math"))]
{
Array2::eye(fock.nrows())
}
};
Ok((eigenvalues, eigenvectors))
} else {
let n = fock.nrows();
let mut eigenvalues = Array1::zeros(n);
let mut eigenvectors = Array2::eye(n);
for i in 0..n {
eigenvalues[i] = fock[[i, i]];
let mut v = Array1::zeros(n);
v[i] = 1.0;
for _ in 0..10 {
let new_v = fock.dot(&v);
let norm = new_v.iter().map(|x| x * x).sum::<f64>().sqrt();
if norm > 1e-10 {
v = new_v / norm;
eigenvalues[i] = v.dot(&fock.dot(&v));
for j in 0..n {
eigenvectors[[j, i]] = v[j];
}
}
}
}
Ok((eigenvalues, eigenvectors))
}
}
pub(super) fn prepare_hartree_fock_state(
&self,
hf_result: &HartreeFockResult,
) -> Result<Array1<Complex64>> {
let num_qubits = 2 * hf_result.molecular_orbitals.num_orbitals;
let mut state = Array1::zeros(1 << num_qubits);
let mut configuration = 0usize;
for i in 0..hf_result.molecular_orbitals.num_orbitals {
if hf_result.molecular_orbitals.occupations[i] >= 1.0 {
configuration |= 1 << (2 * i);
}
if hf_result.molecular_orbitals.occupations[i] >= 2.0 {
configuration |= 1 << (2 * i + 1);
}
}
state[configuration] = Complex64::new(1.0, 0.0);
Ok(state)
}
pub(super) fn create_ansatz_circuit(
&self,
initial_state: &Array1<Complex64>,
) -> Result<InterfaceCircuit> {
let num_qubits = (initial_state.len() as f64).log2() as usize;
let mut circuit = InterfaceCircuit::new(num_qubits, 0);
match self.config.vqe_config.ansatz {
ChemistryAnsatz::UCCSD => {
self.create_uccsd_ansatz(&mut circuit)?;
}
ChemistryAnsatz::HardwareEfficient => {
self.create_hardware_efficient_ansatz(&mut circuit)?;
}
_ => {
self.create_hardware_efficient_ansatz(&mut circuit)?;
}
}
Ok(circuit)
}
pub(super) fn create_uccsd_ansatz(&self, circuit: &mut InterfaceCircuit) -> Result<()> {
let num_qubits = circuit.num_qubits;
for i in 0..num_qubits {
for j in i + 1..num_qubits {
let param_idx = self.vqe_optimizer.parameters.len();
let theta = if param_idx < self.vqe_optimizer.parameters.len() {
self.vqe_optimizer.parameters[param_idx]
} else {
(thread_rng().random::<f64>() - 0.5) * 0.1
};
circuit.add_gate(InterfaceGate::new(InterfaceGateType::RY(theta), vec![i]));
circuit.add_gate(InterfaceGate::new(InterfaceGateType::CNOT, vec![i, j]));
circuit.add_gate(InterfaceGate::new(InterfaceGateType::RY(-theta), vec![j]));
circuit.add_gate(InterfaceGate::new(InterfaceGateType::CNOT, vec![i, j]));
}
}
for i in 0..num_qubits {
for j in i + 1..num_qubits {
for k in j + 1..num_qubits {
for l in k + 1..num_qubits {
circuit.add_gate(InterfaceGate::new(InterfaceGateType::RY(0.0), vec![i]));
circuit.add_gate(InterfaceGate::new(InterfaceGateType::CNOT, vec![i, j]));
circuit.add_gate(InterfaceGate::new(InterfaceGateType::CNOT, vec![j, k]));
circuit.add_gate(InterfaceGate::new(InterfaceGateType::CNOT, vec![k, l]));
circuit.add_gate(InterfaceGate::new(InterfaceGateType::RY(0.0), vec![l]));
circuit.add_gate(InterfaceGate::new(InterfaceGateType::CNOT, vec![k, l]));
circuit.add_gate(InterfaceGate::new(InterfaceGateType::CNOT, vec![j, k]));
circuit.add_gate(InterfaceGate::new(InterfaceGateType::CNOT, vec![i, j]));
}
}
}
}
Ok(())
}
pub(super) fn create_hardware_efficient_ansatz(
&self,
circuit: &mut InterfaceCircuit,
) -> Result<()> {
let num_qubits = circuit.num_qubits;
let num_layers = 3;
for layer in 0..num_layers {
for qubit in 0..num_qubits {
circuit.add_gate(InterfaceGate::new(InterfaceGateType::RY(0.0), vec![qubit]));
circuit.add_gate(InterfaceGate::new(InterfaceGateType::RZ(0.0), vec![qubit]));
}
for qubit in 0..num_qubits - 1 {
circuit.add_gate(InterfaceGate::new(
InterfaceGateType::CNOT,
vec![qubit, qubit + 1],
));
}
if layer % 2 == 1 {
for qubit in 1..num_qubits - 1 {
circuit.add_gate(InterfaceGate::new(
InterfaceGateType::CNOT,
vec![qubit, qubit + 1],
));
}
}
}
Ok(())
}
pub(super) fn apply_ansatz_parameters(
&self,
template: &InterfaceCircuit,
parameters: &Array1<f64>,
) -> Result<InterfaceCircuit> {
let mut circuit = InterfaceCircuit::new(template.num_qubits, 0);
let mut param_index = 0;
for gate in &template.gates {
let new_gate = match gate.gate_type {
InterfaceGateType::RX(_) => {
let param = parameters[param_index];
param_index += 1;
InterfaceGate::new(InterfaceGateType::RX(param), gate.qubits.clone())
}
InterfaceGateType::RY(_) => {
let param = parameters[param_index];
param_index += 1;
InterfaceGate::new(InterfaceGateType::RY(param), gate.qubits.clone())
}
InterfaceGateType::RZ(_) => {
let param = parameters[param_index];
param_index += 1;
InterfaceGate::new(InterfaceGateType::RZ(param), gate.qubits.clone())
}
_ => gate.clone(),
};
circuit.add_gate(new_gate);
}
Ok(circuit)
}
pub(super) fn get_circuit_final_state(
&self,
circuit: &InterfaceCircuit,
) -> Result<Array1<Complex64>> {
let mut simulator = StateVectorSimulator::new();
simulator.initialize_state(circuit.num_qubits)?;
simulator.apply_interface_circuit(circuit)?;
Ok(Array1::from_vec(simulator.get_state()))
}
pub(super) fn run_hartree_fock_only(&self) -> Result<ElectronicStructureResult> {
let hf_result = self.hartree_fock.as_ref().ok_or_else(|| {
SimulatorError::InvalidConfiguration("Hartree-Fock result not available".to_string())
})?;
Ok(ElectronicStructureResult {
ground_state_energy: hf_result.scf_energy,
molecular_orbitals: hf_result.molecular_orbitals.clone(),
density_matrix: hf_result.density_matrix.clone(),
dipole_moment: self.calculate_dipole_moment(&hf_result.density_matrix),
converged: hf_result.converged,
iterations: hf_result.scf_iterations,
quantum_state: Array1::zeros(1),
vqe_history: Vec::new(),
stats: self.stats.clone(),
})
}
pub(super) fn run_quantum_phase_estimation(&mut self) -> Result<ElectronicStructureResult> {
if let (Some(hamiltonian), Some(hf)) = (&self.hamiltonian, &self.hartree_fock) {
let num_qubits = hamiltonian.num_orbitals * 2;
let ancilla_qubits = 8;
let mut qpe_circuit = InterfaceCircuit::new(num_qubits + ancilla_qubits, 0);
for i in 0..ancilla_qubits {
qpe_circuit.add_gate(InterfaceGate::new(InterfaceGateType::Hadamard, vec![i]));
}
self.prepare_qpe_hartree_fock_state(&mut qpe_circuit, ancilla_qubits)?;
for i in 0..ancilla_qubits {
let time_factor = 2.0_f64.powi(i as i32);
self.apply_controlled_hamiltonian_evolution(&mut qpe_circuit, i, time_factor)?;
}
self.apply_inverse_qft(&mut qpe_circuit, 0, ancilla_qubits)?;
let final_state = self.get_circuit_final_state(&qpe_circuit)?;
let energy_estimate =
self.extract_energy_from_qpe_state(&final_state, ancilla_qubits)?;
Ok(ElectronicStructureResult {
ground_state_energy: energy_estimate,
molecular_orbitals: hf.molecular_orbitals.clone(),
density_matrix: hf.density_matrix.clone(),
dipole_moment: self
.fermion_mapper
.calculate_dipole_moment(&hf.density_matrix)?,
converged: true,
iterations: 1,
quantum_state: final_state,
vqe_history: Vec::new(),
stats: self.stats.clone(),
})
} else {
self.run_vqe()
}
}
pub(super) fn prepare_qpe_hartree_fock_state(
&self,
circuit: &mut InterfaceCircuit,
offset: usize,
) -> Result<()> {
if let Some(hf) = &self.hartree_fock {
let num_electrons = if let Some(molecule) = &self.molecule {
molecule.atomic_numbers.iter().sum::<u32>() as usize - molecule.charge as usize
} else {
2
};
let num_orbitals = hf.molecular_orbitals.num_orbitals;
for i in 0..num_electrons.min(num_orbitals) {
circuit.add_gate(InterfaceGate::new(
InterfaceGateType::PauliX,
vec![offset + i],
));
}
}
Ok(())
}
pub(super) fn apply_controlled_hamiltonian_evolution(
&self,
circuit: &mut InterfaceCircuit,
control: usize,
time: f64,
) -> Result<()> {
if let Some(hamiltonian) = &self.hamiltonian {
for i in 0..hamiltonian.num_orbitals {
let angle = time * hamiltonian.one_electron_integrals[[i, i]];
circuit.add_gate(InterfaceGate::new(
InterfaceGateType::CRZ(angle),
vec![control, circuit.num_qubits - hamiltonian.num_orbitals + i],
));
}
}
Ok(())
}
pub(super) fn apply_inverse_qft(
&self,
circuit: &mut InterfaceCircuit,
start: usize,
num_qubits: usize,
) -> Result<()> {
for i in 0..num_qubits {
let qubit = start + i;
for j in (0..i).rev() {
let control = start + j;
let angle = -PI / 2.0_f64.powi((i - j) as i32);
circuit.add_gate(InterfaceGate::new(
InterfaceGateType::CRZ(angle),
vec![control, qubit],
));
}
circuit.add_gate(InterfaceGate::new(InterfaceGateType::Hadamard, vec![qubit]));
}
Ok(())
}
}