qml.qinfo

Overview

This module provides a collection of methods to return quantum information quantities from QNode returning state().

Transforms

QNode transforms for the quantum information quantities.

Functions

classical_fisher(qnode[, argnums])

Returns a function that computes the classical fisher information matrix (CFIM) of a given QNode or quantum tape.

fidelity(qnode0, qnode1, wires0, wires1)

Compute the fidelity for two QNode returning a state() (a state can be a state vector or a density matrix, depending on the device) acting on quantum systems with the same size.

mutual_info(tape, wires0, wires1[, base])

Compute the mutual information from a QuantumTape returning a state():

purity(tape, wires, **kwargs)

Compute the purity of a QuantumTape returning state().

qnode_execution_wrapper(self, qnode, targs, …)

Here, we overwrite the QNode execution wrapper in order to take into account that classical processing may be present inside the QNode.

quantum_fisher(tape, device, *args, **kwargs)

Returns a function that computes the quantum fisher information matrix (QFIM) of a given QNode.

reduced_dm(tape, wires, **kwargs)

Compute the reduced density matrix from a QNode returning state().

relative_entropy(qnode0, qnode1, wires0, wires1)

Compute the relative entropy for two QNode returning a state() (a state can be a state vector or a density matrix, depending on the device) acting on quantum systems with the same size.

trace_distance(qnode0, qnode1, wires0, wires1)

Compute the trace distance for two QNode returning a state() (a state can be a state vector or a density matrix, depending on the device) acting on quantum systems with the same size.

vn_entropy(tape, wires[, base])

Compute the Von Neumann entropy from a QuantumTape returning a state().