Source code for qiskit_aer.library.save_instructions.save_density_matrix

# This code is part of Qiskit.
#
# (C) Copyright IBM 2018, 2021.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.
"""
Simulator instruction to save a density matrix.
"""

from qiskit.circuit import QuantumCircuit
from .save_data import SaveAverageData
from ..default_qubits import default_qubits


[docs]class SaveDensityMatrix(SaveAverageData): """Save a reduced density matrix.""" def __init__( self, num_qubits, label="density_matrix", unnormalized=False, pershot=False, conditional=False, ): """Create new instruction to save the simulator reduced density matrix. Args: num_qubits (int): the number of qubits for the save instruction. label (str): the key for retrieving saved data from results. unnormalized (bool): If True return save the unnormalized accumulated or conditional accumulated density matrix over all shots [Default: False]. pershot (bool): if True save a list of density matrices 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]. """ super().__init__( "save_density_matrix", num_qubits, label, unnormalized=unnormalized, pershot=pershot, conditional=conditional, )
[docs]def save_density_matrix( self, qubits=None, label="density_matrix", unnormalized=False, pershot=False, conditional=False ): """Save the current simulator quantum state as a density matrix. Args: qubits (list or None): the qubits to save reduced density matrix on. If None the full density matrix of qubits will be saved [Default: None]. label (str): the key for retrieving saved data from results. unnormalized (bool): If True return save the unnormalized accumulated or conditional accumulated density matrix over all shots [Default: False]. pershot (bool): if True save a list of density matrices 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]. Returns: QuantumCircuit: with attached instruction. """ qubits = default_qubits(self, qubits=qubits) instr = SaveDensityMatrix( len(qubits), label=label, unnormalized=unnormalized, pershot=pershot, conditional=conditional, ) return self.append(instr, qubits)
QuantumCircuit.save_density_matrix = save_density_matrix