# This code is part of Qiskit.
#
# (C) Copyright IBM 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.
"""
Parallel Experiment class.
"""
from typing import List, Optional
import warnings
import numpy as np
from qiskit import QuantumCircuit, ClassicalRegister
from qiskit.circuit import Clbit
from qiskit.providers.backend import Backend
from qiskit_experiments.exceptions import QiskitError
from .composite_experiment import CompositeExperiment, BaseExperiment
from .composite_analysis import CompositeAnalysis
[docs]
class ParallelExperiment(CompositeExperiment):
"""Combine multiple experiments into a parallel experiment.
Parallel experiments combine individual experiments on disjoint subsets
of qubits into a single composite experiment on the union of those qubits.
The component experiment circuits are combined to run in parallel on the
respective qubits.
Analysis of parallel experiments is performed using the
:class:`~qiskit_experiments.framework.CompositeAnalysis` class which handles
marginalizing the composite experiment circuit data into individual child
:class:`ExperimentData` containers for each component experiment which are
then analyzed using the corresponding analysis class for that component
experiment.
See :class:`~qiskit_experiments.framework.CompositeAnalysis`
documentation for additional information.
"""
def __init__(
self,
experiments: List[BaseExperiment],
backend: Optional[Backend] = None,
flatten_results: bool = None,
analysis: Optional[CompositeAnalysis] = None,
experiment_type: Optional[str] = None,
):
"""Initialize the analysis object.
Args:
experiments: a list of experiments.
backend: Optional, the backend to run the experiment on.
flatten_results: If True flatten all component experiment results
into a single ExperimentData container, including
nested composite experiments. If False save each
component experiment results as a separate child
ExperimentData container. This kwarg is ignored
if the analysis kwarg is used.
analysis: Optional, the composite analysis class to use. If not
provided this will be initialized automatically from the
supplied experiments.
"""
if flatten_results is None:
# Backward compatibility for 0.6
# This if-clause will be removed in 0.7 and flatten_result=True is set in arguments.
warnings.warn(
"Default value of flatten_results will be turned to True in Qiskit Experiments 0.7. "
"If you want child experiment data for each subset experiment, "
"set 'flatten_results=False' explicitly.",
DeprecationWarning,
)
flatten_results = False
qubits = []
for exp in experiments:
qubits += exp.physical_qubits
super().__init__(
experiments,
qubits,
backend=backend,
analysis=analysis,
flatten_results=flatten_results,
experiment_type=experiment_type,
)
[docs]
def circuits(self):
return self._combined_circuits(device_layout=False)
def _transpiled_circuits(self):
return self._combined_circuits(device_layout=True)
def _combined_circuits(self, device_layout: bool) -> List[QuantumCircuit]:
"""Generate combined parallel circuits from transpiled subcircuits."""
if not device_layout:
# Num qubits will be computed from sub experiments
num_qubits = len(self.physical_qubits)
else:
# Work around for backend coupling map circuit inflation
coupling_map = getattr(self.transpile_options, "coupling_map", None)
if coupling_map is None and self.backend:
coupling_map = self._backend_data.coupling_map
if coupling_map is not None:
num_qubits = 1 + max(*self.physical_qubits, np.max(coupling_map))
else:
num_qubits = 1 + max(self.physical_qubits)
joint_circuits = []
sub_qubits = 0
for exp_idx, sub_exp in enumerate(self._experiments):
# Generate transpiled subcircuits
sub_circuits = sub_exp._transpiled_circuits()
# Qubit remapping for non-transpiled circuits
if not device_layout:
qubits = list(range(sub_qubits, sub_qubits + sub_exp.num_qubits))
qargs_map = {q: qubits[i] for i, q in enumerate(sub_exp.physical_qubits)}
sub_qubits += sub_exp.num_qubits
else:
qubits = list(sub_exp.physical_qubits)
qargs_map = {q: q for q in sub_exp.physical_qubits}
for circ_idx, sub_circ in enumerate(sub_circuits):
if circ_idx >= len(joint_circuits):
# Initialize new joint circuit or extract
# existing circuit if already initialized
new_circuit = QuantumCircuit(num_qubits, name=f"parallel_exp_{circ_idx}")
new_circuit.metadata = {
"experiment_type": self._type,
"composite_index": [],
"composite_metadata": [],
"composite_qubits": [],
"composite_clbits": [],
}
joint_circuits.append(new_circuit)
# Add classical registers required by subcircuit
circuit = joint_circuits[circ_idx]
num_clbits = circuit.num_clbits
sub_clbits = sub_circ.num_clbits
clbits = list(range(num_clbits, num_clbits + sub_clbits))
if sub_clbits:
creg = ClassicalRegister(sub_clbits)
sub_cargs = [Clbit(creg, i) for i in range(sub_clbits)]
circuit.add_register(creg)
else:
sub_cargs = []
# Apply transpiled subcircuit
# Note that this assumes the circuit was not expanded to use
# any qubits outside the specified physical qubits
for inst, qargs, cargs in sub_circ.data:
mapped_cargs = [sub_cargs[sub_circ.find_bit(i).index] for i in cargs]
try:
mapped_qargs = [
circuit.qubits[qargs_map[sub_circ.find_bit(i).index]] for i in qargs
]
except KeyError as ex:
# Instruction is outside physical qubits for the component
# experiment.
# This could legitimately happen if the subcircuit was
# explicitly scheduled during transpilation which would
# insert delays on all auxillary device qubits.
# We skip delay instructions to allow for this.
if inst.name == "delay":
continue
raise QiskitError(
"Component experiment has been transpiled outside of the "
"allowed physical qubits for that component. Check the "
"experiment is valid on the backends coupling map."
) from ex
circuit._append(inst, mapped_qargs, mapped_cargs)
# Add subcircuit metadata
circuit.metadata["composite_index"].append(exp_idx)
circuit.metadata["composite_metadata"].append(sub_circ.metadata)
circuit.metadata["composite_qubits"].append(qubits)
circuit.metadata["composite_clbits"].append(clbits)
# Add the calibrations
for gate, cals in sub_circ.calibrations.items():
for key, sched in cals.items():
circuit.add_calibration(gate, qubits=key[0], schedule=sched, params=key[1])
return joint_circuits