State Vector¶

State vector representation module.

This module provides:

StateVector: State vector representation class.

class graphqomb.statevec.StateVector[source]¶

Bases: BaseFullStateSimulator

State vector representation.

__init__(state=None, *, copy=None)[source]¶

property num_qubits: int¶

Get the number of qubits in the state vector.

Returns:: The number of qubits in the state vector.
Return type:: int

state()[source]¶

Get the state vector in external qubit order.

Returns:: The state vector as a numpy array in external qubit order.
Return type:: numpy.typing.NDArray[numpy.complex128]

copy()[source]¶

Create a copy of the state vector.

Returns:: A new StateVector instance with the same state.
Return type:: StateVector

static from_num_qubits(num_qubits)[source]¶

Create a state vector in the plus state with given number of qubits.

Parameters:: num_qubits (int) – Number of qubits in the state vector.
Returns:: The resulting state vector in the plus state.
Return type:: StateVector
Raises:: ValueError – If num_qubits is negative.

static tensor_product(a, b)[source]¶

Tensor product with other state vector, self ⊗ other.

Parameters:

a (StateVector) – first state vector
b (StateVector) – second state vector

Returns:

The resulting state vector after tensor product.

Return type:

StateVector

evolve(operator, qubits)[source]¶

Evolve the state by applying an operator to a subset of qubits.

Parameters:

operator (numpy.typing.NDArray[numpy.complex128]) – The operator to apply.
qubits (int | collections.abc.Sequence[int]) – The qubits to apply the operator to.

measure(qubit, meas_basis, result)[source]¶

Measure a qubit in a given measurement basis.

Parameters:

qubit (int) – The qubit to measure.
meas_basis (MeasBasis) – The measurement basis to use.
result (int) – The measurement result.

add_node(num_qubits)[source]¶

Add plus state to the end of state vector.

Parameters:: num_qubits (int) – number of qubits to add

entangle(qubit1, qubit2)[source]¶

Entangle two qubits.

Parameters:

qubit1 (int) – first qubit index
qubit2 (int) – second qubit index

normalize()[source]¶

Normalize the state.

reorder(permutation)[source]¶

Permute qubits.

if permutation is [2, 0, 1], then # [q0, q1, q2] -> [q1, q2, q0]

Parameters:: permutation (collections.abc.Sequence[int]) – permutation list

norm()[source]¶

Get norm of state vector.

Returns:: norm of state vector
Return type:: float

expectation(operator, qubits)[source]¶

Calculate expectation value of operator.

Parameters:

operator (numpy.typing.NDArray[numpy.complex128]) – Hermitian operator matrix
qubits (int | collections.abc.Sequence[int]) – target qubits

Returns:

expectation value

Return type:

float

Raises:

ValueError – if operator is not Hermitian