qiskit.providers.aer.library.SaveExpectationValueVariance

__init__(operator, label='expectation_value_variance', unnormalized=False, pershot=False, conditional=False)

Instruction to save the expectation value and variance of a Hermitian operator.

The expectation value of a Hermitian operator $H$ for a simulator in quantum state :math`rho`is given by $\langle H\rangle = \text{Tr}[H.\rho]$. The variance is given by $\sigma^2 = \langle H^2 \rangle - \langle H \rangle>^2$.

Parameters

• operator (Pauli orSparsePauliOp orOperator) – a Hermitian operator.
• label (str) – the key for retrieving saved data from results.
• unnormalized (bool) – If True return save the unnormalized accumulated or conditional accumulated expectation value over all shot [Default: False].
• pershot (bool) – if True save a list of expectation values for each shot of the simulation rather than the average over all shots [Default: False].
• conditional (bool) – if True save the average or pershot data conditional on the current classical register values [Default: False].

Raises

ExtensionError – if the input operator is invalid or not Hermitian.

add_decomposition(decomposition)

Add a decomposition of the instruction to the SessionEquivalenceLibrary.

assemble()

Return the QasmQobjInstruction for the intructions.

broadcast_arguments(qargs, cargs)

Validation of the arguments.

Parameters

• qargs (List) – List of quantum bit arguments.
• cargs (List) – List of classical bit arguments.

Yields

Tuple(List, List) – A tuple with single arguments.

Raises

CircuitError – If the input is not valid. For example, the number of arguments does not match the gate expectation.

c_if(classical, val)

Add classical condition on register or cbit classical and value val.

copy(name=None)

Copy of the instruction.

Parameters

name (str) – name to be given to the copied circuit, if None then the name stays the same.

Returns

a copy of the current instruction, with the name

updated if it was provided

Return type

qiskit.circuit.Instruction

Get the decompositions of the instruction from the SessionEquivalenceLibrary.

Return definition in terms of other basic gates.

Get the duration.

inverse()

Special case. Return self.

is_parameterized()

Return True .IFF. instruction is parameterized else False

Return instruction label

Return type

str

mirror()

DEPRECATED: use instruction.reverse_ops().

Returns

a new instruction with sub-instructions

reversed.

Return type

qiskit.circuit.Instruction

return instruction params.

qasm()

Return a default OpenQASM string for the instruction.

Derived instructions may override this to print in a different format (e.g. measure q[0] -> c[0];).

repeat(n)

Creates an instruction with gate repeated n amount of times.

Parameters

n (int) – Number of times to repeat the instruction

Returns

Containing the definition.

Return type

qiskit.circuit.Instruction

Raises

CircuitError – If n < 1.

reverse_ops()

For a composite instruction, reverse the order of sub-instructions.

This is done by recursively reversing all sub-instructions. It does not invert any gate.

Returns

a new instruction with

sub-instructions reversed.

Return type

qiskit.circuit.Instruction

soft_compare(other)

Soft comparison between gates. Their names, number of qubits, and classical bit numbers must match. The number of parameters must match. Each parameter is compared. If one is a ParameterExpression then it is not taken into account.

Parameters

other (instruction) – other instruction.

Returns

are self and other equal up to parameter expressions.

Return type

bool

Get the time unit of duration.

validate_parameter(parameter)

Instruction parameters has no validation or normalization.