# SnapshotDensityMatrix¶

class SnapshotDensityMatrix(label, num_qubits)[source]

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.

Attributes

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

Methods

 Add a decomposition of the instruction to the SessionEquivalenceLibrary. Assemble a QasmQobjInstruction Validation of the arguments. SnapshotDensityMatrix.c_if(classical, val) Add classical condition on register classical and value val. Copy of the instruction. Defines qubits to snapshot for all snapshot methods Special case. Return True .IFF. DEPRECATED: use instruction.reverse_ops(). Return a default OpenQASM string for the instruction. Creates an instruction with gate repeated n amount of times. For a composite instruction, reverse the order of sub-instructions.