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SnapshotExpectationValue

SnapshotExpectationValue(label, op, single_shot=False, variance=False) GitHub(opens in a new tab)

Snapshot instruction for supported methods of Qasm simulator.

Create a probability snapshot instruction.

Parameters

  • label (str) – the snapshot label.
  • op (Operator) – operator to snapshot.
  • single_shot (bool) – return list for each shot rather than average [Default: False]
  • variance (bool) – compute variance of probabilities [Default: False]

Raises

ExtensionError – if snapshot is invalid.


Attributes

decompositions

Get the decompositions of the instruction from the SessionEquivalenceLibrary.

definition

Return definition in terms of other basic gates.

label

Return snapshot label

params

return instruction params.

snapshot_type

Return snapshot type


Methods

add_decomposition

SnapshotExpectationValue.add_decomposition(decomposition)

Add a decomposition of the instruction to the SessionEquivalenceLibrary.

assemble

SnapshotExpectationValue.assemble()

Assemble a QasmQobjInstruction for snapshot_expectation_value.

broadcast_arguments

SnapshotExpectationValue.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

SnapshotExpectationValue.c_if(classical, val)

Add classical condition on register classical and value val.

copy

SnapshotExpectationValue.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

define_snapshot_register

static SnapshotExpectationValue.define_snapshot_register(circuit, label, qubits=None)

Defines qubits to snapshot for all snapshot methods

inverse

SnapshotExpectationValue.inverse()

Special case. Return self.

is_parameterized

SnapshotExpectationValue.is_parameterized()

Return True .IFF. instruction is parameterized else False

mirror

SnapshotExpectationValue.mirror()

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

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

Returns

a fresh gate with sub-gates reversed

Return type

qiskit.circuit.Instruction

qasm

SnapshotExpectationValue.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

SnapshotExpectationValue.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.

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