Struct PauliString 

pub struct PauliString { /* private fields */ }

Represents a Pauli string, which is a product of Pauli operators (X, Y, Z) acting on qubits. Used to represent a term in a Hamiltonian or a quantum operator.

Implementations

impl PauliString

pub fn new(coefficient: Complex<f64>) -> Self

Creates a new Pauli string with the given coefficient and an empty set of operators.

Arguments

• coefficient - The coefficient of the Pauli string, represented as a complex number.

Returns

A new PauliString instance with the specified coefficient and no operators.

pub fn len(&self) -> usize

Returns the length of the Pauli string, defined as the number of operators it contains.

Returns

• usize - The number of operators in the Pauli string.

pub fn with_ops(coefficient: Complex<f64>, ops: HashMap<usize, Pauli>) -> Self

Creates a new Pauli string with the given coefficient and a set of operators.

Arguments

• coefficient - The coefficient of the Pauli string, represented as a complex number.
• ops - A mapping from qubit indices to Pauli operators.

Returns

A new PauliString instance with the specified coefficient and operators.

Note that the Hashmap ensures uniqueness of operators for each qubit.

pub fn add_op(&mut self, qubit: usize, op: Pauli)

Adds a Pauli operator to the Pauli string at the specified qubit index.

Arguments

• qubit - The index of the qubit to which the operator is applied.
• op - The Pauli operator to be added (X, Y, or Z).

Panics

This function will panic if an operator for the same qubit index is added more than once.

pub fn with_op(self, qubit: usize, op: Pauli) -> Self

Adds a Pauli operator to the Pauli string at the specified qubit index and returns the new PauliString instance.

Arguments

• qubit - The index of the qubit to which the operator is applied.
• op - The Pauli operator to be added (X, Y, or Z).

Returns

• Self - A new PauliString instance with the added operator.

Panics

This function will panic if an operator for the same qubit index is added more than once.

pub fn coefficient(&self) -> Complex<f64>

Returns the coefficient of the Pauli string.

Returns

• Complex<f64> - The coefficient of the Pauli string, represented as a complex number.

pub fn ops(&self) -> &HashMap<usize, Pauli>

Returns a reference to the operators in the Pauli string.

Returns

• &HashMap<usize, Pauli> - A reference to the mapping of qubit indices to Pauli operators.

pub fn get_targets(&self) -> Vec<usize>

Returns the list of targets of the Pauli string

Returns

• Vec<usize> - A vector of qubit indices that the Pauli string acts upon.

pub fn to_gates(&self) -> Vec<Gate>

Converts the Pauli string to a vector of operator gates.

Returns

• Vec<Gate> - A vector of Gate structs representing the individual Pauli operators.

pub fn apply(&self, state: &State) -> Result<State, Error>

Applies the Pauli string to a given state.

Arguments

• state - The state to which the Pauli string is applied.

Returns

• Result<State, Error> - The resulting state after applying the Pauli string, or an error if the operation fails.

Errors

• Returns an error if the operations in the Pauli string refer to qubits outside the range of the state.

pub fn apply_normalised(&self, state: &State) -> Result<State, Error>

Applies the Pauli string to a given state and normalises the new state.

Arguments

• state - The state to which the Pauli string is applied.

Returns

• Result<State, Error> - The resulting state after applying the Pauli string, or an error if the operation fails.

Errors

• Returns an error if the operations in the Pauli string refer to qubits outside the range of the state.
• Returns an error if the resulting state cannot be normalised (eg., has zero norm).

pub fn apply_exp(&self, state: &State) -> Result<State, Error>

Applies the exponential of the Pauli string to a given state.

Arguments

• state - The state to which the exponential of the Pauli string is applied.

Returns

• Result<State, Error> - The resulting state after applying the exponential of the Pauli string, or an error if the operation fails.

Errors

• Returns an error if the operations in the Pauli string refer to qubits outside the range of the state.

pub fn apply_exp_factor( &self, state: &State, factor: Complex<f64>, ) -> Result<State, Error>

Applies the exponential of the Pauli string to a given state with a specified factor.

Arguments

• state - The state to which the exponential of the Pauli string is applied.
• factor - A complex factor to be multiplied with the coefficient of the Pauli string.

Returns

• Result<State, Error> - The resulting state after applying the exponential of the Pauli string with the factor, or an error if the operation fails.

Errors

• Returns an error if the operations in the Pauli string refer to qubits outside the range of the state.

pub fn apply_exp_neg_i_dt(&self, state: &State, dt: f64) -> Result<State, Error>

Applies the exponential of the Pauli string to the given state with a negative imaginary factor. Represents a time evolution step of the form exp(-i * coefficient * P_ops * dt). Guaranteed to return a normalised state if the input state is normalised.

Arguments

• state - The state to which the exponential of the Pauli string is applied.
• dt - The time step for the evolution.

Returns

• Result<State, Error> - The resulting state after applying the exponential of the Pauli string with the negative imaginary factor, or an error if the operation fails.

Errors

• Returns an error if the operations in the Pauli string refer to qubits outside the range of the state.
• Returns an error if the coefficient for the Pauli string has an imaginary component.

pub fn hermitian_conjugate(&self) -> Self

Returns the Hermitian conjugate of the Pauli string.

Returns

• Self - A new PauliString instance representing the Hermitian conjugate of the original Pauli string.

Trait Implementations

impl Add<PauliString> for SumOp

type Output = SumOp

The resulting type after applying the + operator.

fn add(self, other: PauliString) -> Self::Output

Performs the + operation.

impl Add for PauliString

type Output = SumOp

The resulting type after applying the + operator.

fn add(self, other: Self) -> Self::Output

Performs the + operation.

impl Clone for PauliString

fn clone(&self) -> PauliString

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PauliString

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for PauliString

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Mul<Complex<f64>> for PauliString

type Output = PauliString

The resulting type after applying the * operator.

fn mul(self, rhs: Complex<f64>) -> Self::Output

Performs the * operation.

impl Mul<PauliString> for f64

type Output = PauliString

The resulting type after applying the * operator.

fn mul(self, rhs: PauliString) -> Self::Output

Performs the * operation.

impl Mul<f64> for PauliString

type Output = PauliString

The resulting type after applying the * operator.

fn mul(self, rhs: f64) -> Self::Output

Performs the * operation.

impl PartialEq for PauliString

fn eq(&self, other: &PauliString) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for PauliString