Struct ParametricCircuit 

pub struct ParametricCircuit {
    pub gates: Vec<Box<dyn ParametricGate>>,
    pub num_qubits: usize,
    pub num_parameters: usize,
}

Parametric quantum circuit for VQE

Fields

gates: Vec<Box<dyn ParametricGate>>

Sequence of parametric gates

num_qubits: usize

Number of qubits

num_parameters: usize

Number of parameters

Implementations

impl ParametricCircuit

pub fn new(num_qubits: usize) -> Self

Create new parametric circuit

pub fn add_gate(&mut self, gate: Box<dyn ParametricGate>)

Add a parametric gate

pub fn rx(&mut self, qubit: usize, param_idx: usize)

Add RX gate

pub fn ry(&mut self, qubit: usize, param_idx: usize)

Add RY gate

pub fn rz(&mut self, qubit: usize, param_idx: usize)

Add RZ gate

pub fn cnot(&mut self, control: usize, target: usize)

Add a (non-parametric) CNOT gate, used to build entangling layers.

pub fn evaluate(&self, params: &[f64]) -> Result<Array1<Complex64>>

Evaluate the circuit for the given parameters and return the final state vector.

Starts from |0...0> and applies each parametric gate’s matrix to the dense state vector in sequence. Amplitudes use the little-endian convention (qubit q maps to bit q of the basis index), matching [compute_pauli_expectation_from_state] so expectation values and parameter-shift gradients are computed on the genuine state produced by the circuit rather than a fixed placeholder.

pub fn gradient_expectation( &self, observable: &PauliOperatorSum, params: &[f64], method: GradientMethod, ) -> Result<Vec<f64>>

Compute gradient of expectation value using parameter-shift rule