qiskit.providers.aer.extensions.SnapshotDensityMatrix

class SnapshotDensityMatrix(label, num_qubits)

Snapshot instruction for density matrix method of Qasm simulator.

Create a density matrix state snapshot instruction.

Parameters

• label (str) – the snapshot label.

• num_qubits (int) – the number of qubits to snapshot.

Raises

ExtensionError – if snapshot is invalid.

__init__(label, num_qubits)

Create a density matrix state snapshot instruction.

Parameters

• label (str) – the snapshot label.

• num_qubits (int) – the number of qubits to snapshot.

Raises

ExtensionError – if snapshot is invalid.

Methods

__init__(label, num_qubits)	Create a density matrix state snapshot instruction.
add_decomposition(decomposition)	Add a decomposition of the instruction to the SessionEquivalenceLibrary.
assemble()	Assemble a QasmQobjInstruction
broadcast_arguments(qargs, cargs)	Validation of the arguments.
c_if(classical, val)	Add classical condition on register classical and value val.
copy([name])	Copy of the instruction.
define_snapshot_register(circuit[, label, …])	Defines qubits to snapshot for all snapshot methods
inverse()	Special case.
is_parameterized()	Return True .IFF.
mirror()	DEPRECATED: use instruction.reverse_ops().
qasm()	Return a default OpenQASM string for the instruction.
repeat(n)	Creates an instruction with gate repeated n amount of times.
reverse_ops()	For a composite instruction, reverse the order of sub-instructions.
validate_parameter(parameter)	Instruction parameters has no validation or normalization.

Attributes

decompositions	Get the decompositions of the instruction from the SessionEquivalenceLibrary.
definition	Return definition in terms of other basic gates.
duration	Get the duration.
label	Return snapshot label
params	return instruction params.
snapshot_type	Return snapshot type
unit	Get the time unit of duration.

add_decomposition(decomposition)

Add a decomposition of the instruction to the SessionEquivalenceLibrary.

assemble()

Assemble a QasmQobjInstruction

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 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

property decompositions

Get the decompositions of the instruction from the SessionEquivalenceLibrary.

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

Defines qubits to snapshot for all snapshot methods

property definition

Return definition in terms of other basic gates.

property duration

Get the duration.

inverse()

Special case. Return self.

is_parameterized()

Return True .IFF. instruction is parameterized else False

property label

Return snapshot label

mirror()

DEPRECATED: use instruction.reverse_ops().

Returns

a new instruction with sub-instructions

reversed.

Return type

qiskit.circuit.Instruction

property params

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

property snapshot_type

Return snapshot type

property unit

Get the time unit of duration.

validate_parameter(parameter)

Instruction parameters has no validation or normalization.