# This code is part of Qiskit.
#
# (C) Copyright IBM 2017, 2020.
#
# 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.
"""Synthesize UnitaryGates."""
from math import pi, inf
from typing import List, Union
from copy import deepcopy
from itertools import product
from qiskit.converters import circuit_to_dag
from qiskit.transpiler import CouplingMap, Target
from qiskit.transpiler.basepasses import TransformationPass
from qiskit.transpiler.exceptions import TranspilerError
from qiskit.dagcircuit.dagcircuit import DAGCircuit
from qiskit.quantum_info.synthesis import one_qubit_decompose
from qiskit.quantum_info.synthesis.xx_decompose import XXDecomposer
from qiskit.quantum_info.synthesis.two_qubit_decompose import TwoQubitBasisDecomposer
from qiskit.circuit import ControlFlowOp
from qiskit.circuit.parameter import Parameter
from qiskit.circuit.library.standard_gates import (
iSwapGate,
CXGate,
CZGate,
RXXGate,
RZXGate,
ECRGate,
)
from qiskit.transpiler.passes.synthesis import plugin
from qiskit.transpiler.passes.utils import control_flow
from qiskit.providers.models import BackendProperties
KAK_GATE_NAMES = {
"cx": CXGate(),
"cz": CZGate(),
"iswap": iSwapGate(),
"rxx": RXXGate(pi / 2),
"ecr": ECRGate(),
"rzx": RZXGate(pi / 4), # typically pi/6 is also available
}
def _choose_kak_gate(basis_gates):
"""Choose the first available 2q gate to use in the KAK decomposition."""
kak_gate = None
kak_gates = set(basis_gates or []).intersection(KAK_GATE_NAMES.keys())
if kak_gates:
kak_gate = KAK_GATE_NAMES[kak_gates.pop()]
return kak_gate
def _find_matching_kak_gates(target):
"""Return list of available 2q gates to use in the KAK decomposition."""
kak_gates = []
for name in target:
if name in KAK_GATE_NAMES:
kak_gates.append(KAK_GATE_NAMES[name])
continue
op = target.operation_from_name(name)
if isinstance(op, RXXGate) and (
isinstance(op.params[0], Parameter) or op.params[0] == pi / 2
):
kak_gates.append((KAK_GATE_NAMES["rxx"], name))
elif isinstance(op, RZXGate) and (
isinstance(op.params[0], Parameter) or op.params[0] == pi / 4
):
kak_gates.append((KAK_GATE_NAMES["rzx"], name))
return kak_gates
def _choose_euler_basis(basis_gates):
"""Choose the first available 1q basis to use in the Euler decomposition."""
basis_set = set(basis_gates or [])
for basis, gates in one_qubit_decompose.ONE_QUBIT_EULER_BASIS_GATES.items():
if set(gates).issubset(basis_set):
return basis
return None
def _find_matching_euler_bases(target):
"""Find matching availablee 1q basis to use in the Euler decomposition."""
euler_basis_gates = []
basis_set = target.keys()
for basis, gates in one_qubit_decompose.ONE_QUBIT_EULER_BASIS_GATES.items():
if set(gates).issubset(basis_set):
euler_basis_gates.append(basis)
return euler_basis_gates
def _choose_bases(basis_gates, basis_dict=None):
"""Find the matching basis string keys from the list of basis gates from the backend."""
if basis_gates is None:
basis_set = set()
else:
basis_set = set(basis_gates)
if basis_dict is None:
basis_dict = one_qubit_decompose.ONE_QUBIT_EULER_BASIS_GATES
out_basis = []
for basis, gates in basis_dict.items():
if set(gates).issubset(basis_set):
out_basis.append(basis)
return out_basis
def _basis_gates_to_decomposer_2q(basis_gates, pulse_optimize=None):
kak_gate = _choose_kak_gate(basis_gates)
euler_basis = _choose_euler_basis(basis_gates)
if isinstance(kak_gate, RZXGate):
backup_optimizer = TwoQubitBasisDecomposer(
CXGate(), euler_basis=euler_basis, pulse_optimize=pulse_optimize
)
return XXDecomposer(euler_basis=euler_basis, backup_optimizer=backup_optimizer)
elif kak_gate is not None:
return TwoQubitBasisDecomposer(
kak_gate, euler_basis=euler_basis, pulse_optimize=pulse_optimize
)
else:
return None
[문서]class UnitarySynthesis(TransformationPass):
"""Synthesize gates according to their basis gates."""
def __init__(
self,
basis_gates: List[str] = None,
approximation_degree: float = 1,
coupling_map: CouplingMap = None,
backend_props: BackendProperties = None,
pulse_optimize: Union[bool, None] = None,
natural_direction: Union[bool, None] = None,
synth_gates: Union[List[str], None] = None,
method: str = "default",
min_qubits: int = None,
plugin_config: dict = None,
target: Target = None,
):
"""Synthesize unitaries over some basis gates.
This pass can approximate 2-qubit unitaries given some
approximation closeness measure (expressed as
``approximation_degree``). Other unitaries are synthesized
exactly.
Args:
basis_gates (list[str]): List of gate names to target. If this is
not specified the ``target`` argument must be used. If both this
and the ``target`` are specified the value of ``target`` will
be used and this will be ignored.
approximation_degree (float): Closeness of approximation
(0: lowest, 1: highest).
coupling_map (CouplingMap): the coupling map of the backend
in case synthesis is done on a physical circuit. The
directionality of the coupling_map will be taken into
account if ``pulse_optimize`` is ``True``/``None`` and ``natural_direction``
is ``True``/``None``.
backend_props (BackendProperties): Properties of a backend to
synthesize for (e.g. gate fidelities).
pulse_optimize (bool): Whether to optimize pulses during
synthesis. A value of ``None`` will attempt it but fall
back if it does not succeed. A value of ``True`` will raise
an error if pulse-optimized synthesis does not succeed.
natural_direction (bool): Whether to apply synthesis considering
directionality of 2-qubit gates. Only applies when
``pulse_optimize`` is ``True`` or ``None``. The natural direction is
determined by first checking to see whether the
coupling map is unidirectional. If there is no
coupling map or the coupling map is bidirectional,
the gate direction with the shorter
duration from the backend properties will be used. If
set to True, and a natural direction can not be
determined, raises :class:`~TranspileError`. If set to None, no
exception will be raised if a natural direction can
not be determined.
synth_gates (list[str]): List of gates to synthesize. If None and
``pulse_optimize`` is False or None, default to
``['unitary']``. If ``None`` and ``pulse_optimize == True``,
default to ``['unitary', 'swap']``
method (str): The unitary synthesis method plugin to use.
min_qubits: The minimum number of qubits in the unitary to synthesize. If this is set
and the unitary is less than the specified number of qubits it will not be
synthesized.
plugin_config: Optional extra configuration arguments (as a ``dict``)
which are passed directly to the specified unitary synthesis
plugin. By default, this will have no effect as the default
plugin has no extra arguments. Refer to the documentation of
your unitary synthesis plugin on how to use this.
target: The optional :class:`~.Target` for the target device the pass
is compiling for. If specified this will supersede the values
set for ``basis_gates``, ``coupling_map``, and ``backend_props``.
"""
super().__init__()
self._basis_gates = set(basis_gates or ())
self._approximation_degree = approximation_degree
self._min_qubits = min_qubits
self.method = method
self.plugins = None
if method != "default":
self.plugins = plugin.UnitarySynthesisPluginManager()
self._coupling_map = coupling_map
self._backend_props = backend_props
self._pulse_optimize = pulse_optimize
self._natural_direction = natural_direction
self._plugin_config = plugin_config
self._target = target
if target is not None:
self._coupling_map = self._target.build_coupling_map()
if synth_gates:
self._synth_gates = synth_gates
else:
if pulse_optimize:
self._synth_gates = ["unitary", "swap"]
else:
self._synth_gates = ["unitary"]
self._synth_gates = set(self._synth_gates) - self._basis_gates
[문서] def run(self, dag: DAGCircuit) -> DAGCircuit:
"""Run the UnitarySynthesis pass on ``dag``.
Args:
dag: input dag.
Returns:
Output dag with UnitaryGates synthesized to target basis.
Raises:
TranspilerError: if ``method`` was specified for the class and is not
found in the installed plugins list. The list of installed
plugins can be queried with
:func:`~qiskit.transpiler.passes.synthesis.plugin.unitary_synthesis_plugin_names`
"""
if self.method != "default" and self.method not in self.plugins.ext_plugins:
raise TranspilerError("Specified method: %s not found in plugin list" % self.method)
# Return fast if we have no synth gates (ie user specified an empty
# list or the synth gates are all in the basis
if not self._synth_gates:
return dag
if self.plugins:
plugin_method = self.plugins.ext_plugins[self.method].obj
else:
plugin_method = DefaultUnitarySynthesis()
plugin_kwargs = {"config": self._plugin_config}
_gate_lengths = _gate_errors = None
if self.method == "default":
# If the method is the default, we only need to evaluate one set of keyword arguments.
# To simplify later logic, and avoid cases where static analysis might complain that we
# haven't initialised the "default" handler, we rebind the names so they point to the
# same object as the chosen method.
default_method = plugin_method
default_kwargs = plugin_kwargs
method_list = [(plugin_method, plugin_kwargs)]
else:
# If the method is not the default, we still need to initialise the default plugin's
# keyword arguments in case we have to fall back on it during the actual run.
default_method = self.plugins.ext_plugins["default"].obj
default_kwargs = {}
method_list = [(plugin_method, plugin_kwargs), (default_method, default_kwargs)]
for method, kwargs in method_list:
if method.supports_basis_gates:
kwargs["basis_gates"] = self._basis_gates
if method.supports_natural_direction:
kwargs["natural_direction"] = self._natural_direction
if method.supports_pulse_optimize:
kwargs["pulse_optimize"] = self._pulse_optimize
if method.supports_gate_lengths:
_gate_lengths = _gate_lengths or _build_gate_lengths(
self._backend_props, self._target
)
kwargs["gate_lengths"] = _gate_lengths
if method.supports_gate_errors:
_gate_errors = _gate_errors or _build_gate_errors(self._backend_props, self._target)
kwargs["gate_errors"] = _gate_errors
supported_bases = method.supported_bases
if supported_bases is not None:
kwargs["matched_basis"] = _choose_bases(self._basis_gates, supported_bases)
if method.supports_target:
kwargs["target"] = self._target
# Handle approximation degree as a special case for backwards compatibility, it's
# not part of the plugin interface and only something needed for the default
# pass.
# pylint: disable=attribute-defined-outside-init
default_method._approximation_degree = self._approximation_degree
if self.method == "default":
# pylint: disable=attribute-defined-outside-init
plugin_method._approximation_degree = self._approximation_degree
return self._run_main_loop(
dag, plugin_method, plugin_kwargs, default_method, default_kwargs
)
def _run_main_loop(self, dag, plugin_method, plugin_kwargs, default_method, default_kwargs):
"""Inner loop for the optimizer, after all DAG-independent set-up has been completed."""
def _recurse(dag):
# This isn't quite a trivially recursive call because we need to close over the
# arguments to the function. The loop is sufficiently long that it's cleaner to do it
# in a separate method rather than define a helper closure within `self.run`.
return self._run_main_loop(
dag, plugin_method, plugin_kwargs, default_method, default_kwargs
)
for node in dag.op_nodes(ControlFlowOp):
node.op = control_flow.map_blocks(_recurse, node.op)
dag_bit_indices = (
{bit: i for i, bit in enumerate(dag.qubits)}
if plugin_method.supports_coupling_map or default_method.supports_coupling_map
else {}
)
for node in dag.named_nodes(*self._synth_gates):
if self._min_qubits is not None and len(node.qargs) < self._min_qubits:
continue
synth_dag = None
unitary = node.op.to_matrix()
n_qubits = len(node.qargs)
if (plugin_method.max_qubits is not None and n_qubits > plugin_method.max_qubits) or (
plugin_method.min_qubits is not None and n_qubits < plugin_method.min_qubits
):
method, kwargs = default_method, default_kwargs
else:
method, kwargs = plugin_method, plugin_kwargs
if method.supports_coupling_map:
kwargs["coupling_map"] = (
self._coupling_map,
[dag_bit_indices[x] for x in node.qargs],
)
synth_dag = method.run(unitary, **kwargs)
if synth_dag is not None:
if isinstance(synth_dag, tuple):
dag.substitute_node_with_dag(node, synth_dag[0], wires=synth_dag[1])
else:
dag.substitute_node_with_dag(node, synth_dag)
return dag
def _build_gate_lengths(props=None, target=None):
gate_lengths = {}
if target is not None:
for gate, prop_dict in target.items():
gate_lengths[gate] = {}
for qubit, gate_props in prop_dict.items():
if gate_props is not None and gate_props.duration is not None:
gate_lengths[gate][qubit] = gate_props.duration
elif props is not None:
for gate in props._gates:
gate_lengths[gate] = {}
for k, v in props._gates[gate].items():
length = v.get("gate_length")
if length:
gate_lengths[gate][k] = length[0]
if not gate_lengths[gate]:
del gate_lengths[gate]
return gate_lengths
def _build_gate_errors(props=None, target=None):
gate_errors = {}
if target is not None:
for gate, prop_dict in target.items():
gate_errors[gate] = {}
for qubit, gate_props in prop_dict.items():
if gate_props is not None and gate_props.error is not None:
gate_errors[gate][qubit] = gate_props.error
if props is not None:
for gate in props._gates:
gate_errors[gate] = {}
for k, v in props._gates[gate].items():
error = v.get("gate_error")
if error:
gate_errors[gate][k] = error[0]
if not gate_errors[gate]:
del gate_errors[gate]
return gate_errors
class DefaultUnitarySynthesis(plugin.UnitarySynthesisPlugin):
"""The default unitary synthesis plugin."""
@property
def supports_basis_gates(self):
return True
@property
def supports_coupling_map(self):
return True
@property
def supports_natural_direction(self):
return True
@property
def supports_pulse_optimize(self):
return True
@property
def supports_gate_lengths(self):
return True
@property
def supports_gate_errors(self):
return True
@property
def max_qubits(self):
return None
@property
def min_qubits(self):
return None
@property
def supported_bases(self):
return None
@property
def supports_target(self):
return True
def __init__(self):
super().__init__()
self._decomposer_cache = {}
def _find_decomposer_2q_from_target(self, target, qubits, pulse_optimize):
qubits_tuple = tuple(qubits)
reverse_tuple = (qubits[1], qubits[0])
if qubits_tuple in self._decomposer_cache:
return self._decomposer_cache[qubits_tuple]
matching = {}
reverse = {}
kak_gates = _find_matching_kak_gates(target)
euler_basis_gates = _find_matching_euler_bases(target)
decomposers_2q = []
# find all decomposers
for kak_gate, euler_basis in product(kak_gates, euler_basis_gates):
gate_name = None
if isinstance(kak_gate, tuple):
gate_name = kak_gate[1]
kak_gate = kak_gate[0]
if isinstance(kak_gate, RZXGate):
backup_optimizer = TwoQubitBasisDecomposer(
CXGate(), euler_basis=euler_basis, pulse_optimize=pulse_optimize
)
decomposer = XXDecomposer(
euler_basis=euler_basis, backup_optimizer=backup_optimizer
)
if gate_name is not None:
decomposer.gate_name = gate_name
decomposers_2q.append(decomposer)
elif kak_gate is not None:
decomposer = TwoQubitBasisDecomposer(
kak_gate, euler_basis=euler_basis, pulse_optimize=pulse_optimize
)
if gate_name is not None:
decomposer.gate_name = gate_name
decomposers_2q.append(decomposer)
# Find lowest error matching or reverse decomposer and use that
for index, decomposer in enumerate(decomposers_2q):
gate_name = getattr(decomposer, "gate_name", decomposer.gate.name)
props_dict = target[gate_name]
if target.instruction_supported(gate_name, qubits_tuple):
if props_dict is None or None in props_dict:
error = 0.0
else:
error = getattr(props_dict[qubits_tuple], "error", 0.0)
if error is None:
error = 0.0
matching[index] = error
# Skip reverse check if we already have matching
elif not matching and target.instruction_supported(gate_name, reverse_tuple):
if props_dict is None or None in props_dict:
error = 0.0
else:
error = getattr(props_dict[reverse_tuple], "error", 0.0)
if error is None:
error = 0.0
reverse[index] = error
preferred_direction = None
if matching:
preferred_direction = [0, 1]
min_error_index = min(matching, key=matching.get)
decomposer2q = decomposers_2q[min_error_index]
elif reverse:
preferred_direction = [1, 0]
min_error_index = min(reverse, key=reverse.get)
decomposer2q = decomposers_2q[min_error_index]
# If no matching or reverse direction is found just pick one, if natural direction is
# enforced it will fail later
else:
decomposer2q = decomposers_2q[0]
self._decomposer_cache[qubits_tuple] = (decomposer2q, preferred_direction)
return (decomposer2q, preferred_direction)
def run(self, unitary, **options):
# Approximation degree is set directly as an attribute on the
# instance by the UnitarySynthesis pass here as it's not part of
# plugin interface. However if for some reason it's not set assume
# it's 1.
approximation_degree = getattr(self, "_approximation_degree", 1)
basis_gates = options["basis_gates"]
coupling_map = options["coupling_map"][0]
natural_direction = options["natural_direction"]
pulse_optimize = options["pulse_optimize"]
gate_lengths = options["gate_lengths"]
gate_errors = options["gate_errors"]
qubits = options["coupling_map"][1]
target = options["target"]
synth_dag = None
wires = None
if unitary.shape == (2, 2):
if target is not None:
euler_basis = _choose_euler_basis(target.operation_names_for_qargs(tuple(qubits)))
else:
euler_basis = _choose_euler_basis(basis_gates)
if euler_basis is not None:
decomposer1q = one_qubit_decompose.OneQubitEulerDecomposer(euler_basis)
else:
decomposer1q = None
if decomposer1q is None:
return None
synth_dag = circuit_to_dag(decomposer1q._decompose(unitary))
elif unitary.shape == (4, 4):
preferred_direction = None
if target is not None:
decomposer2q, preferred_direction = self._find_decomposer_2q_from_target(
target, qubits, pulse_optimize
)
else:
decomposer2q = _basis_gates_to_decomposer_2q(
basis_gates, pulse_optimize=pulse_optimize
)
if not decomposer2q:
return None
synth_dag, wires = self._synth_natural_direction(
unitary,
coupling_map,
qubits,
decomposer2q,
gate_lengths,
gate_errors,
natural_direction,
approximation_degree,
pulse_optimize,
target,
preferred_direction,
)
else:
from qiskit.quantum_info.synthesis.qsd import ( # pylint: disable=cyclic-import
qs_decomposition,
)
synth_dag = circuit_to_dag(qs_decomposition(unitary))
return synth_dag, wires
def _synth_natural_direction(
self,
su4_mat,
coupling_map,
qubits,
decomposer2q,
gate_lengths,
gate_errors,
natural_direction,
approximation_degree,
pulse_optimize,
target,
preferred_direction=None,
):
synth_direction = None
physical_gate_fidelity = None
wires = None
if natural_direction in {None, True} and (
coupling_map or (target is not None and decomposer2q and not preferred_direction)
):
if coupling_map is not None:
cmap = coupling_map
else:
cmap = target.build_coupling_map()
# If we don't have a defined coupling map (either from the input)
# or from the target we can't check for a natural direction
if cmap is not None:
neighbors0 = cmap.neighbors(qubits[0])
zero_one = qubits[1] in neighbors0
neighbors1 = cmap.neighbors(qubits[1])
one_zero = qubits[0] in neighbors1
if zero_one and not one_zero:
preferred_direction = [0, 1]
if one_zero and not zero_one:
preferred_direction = [1, 0]
if (
natural_direction in {None, True}
and preferred_direction is None
and (gate_lengths and gate_errors)
):
len_0_1 = inf
len_1_0 = inf
gate_name = getattr(decomposer2q, "gate_name", decomposer2q.gate.name)
twoq_gate_lengths = gate_lengths.get(gate_name)
if twoq_gate_lengths:
len_0_1 = twoq_gate_lengths.get((qubits[0], qubits[1]), inf)
len_1_0 = twoq_gate_lengths.get((qubits[1], qubits[0]), inf)
if len_0_1 < len_1_0:
preferred_direction = [0, 1]
elif len_1_0 < len_0_1:
preferred_direction = [1, 0]
if preferred_direction:
twoq_gate_errors = gate_errors.get(gate_name)
gate_error = twoq_gate_errors.get(
(qubits[preferred_direction[0]], qubits[preferred_direction[1]])
)
if gate_error:
physical_gate_fidelity = 1 - gate_error
if natural_direction is True and preferred_direction is None:
raise TranspilerError(
f"No preferred direction of gate on qubits {qubits} "
"could be determined from coupling map or "
"gate lengths."
)
if approximation_degree is not None:
basis_fidelity = approximation_degree
else:
basis_fidelity = physical_gate_fidelity
if not isinstance(decomposer2q, XXDecomposer):
synth_circ = decomposer2q(su4_mat, basis_fidelity=basis_fidelity)
else:
synth_circ = decomposer2q(su4_mat)
synth_dag = circuit_to_dag(synth_circ)
# if a natural direction exists but the synthesis is in the opposite direction,
# resynthesize a new operator which is the original conjugated by swaps.
# this new operator is doubly mirrored from the original and is locally equivalent.
synth_dag_qubit_index = {qubit: index for index, qubit in enumerate(synth_dag.qubits)}
if synth_dag.two_qubit_ops():
synth_direction = [
synth_dag_qubit_index[qubit] for qubit in synth_dag.two_qubit_ops()[0].qargs
]
if (
preferred_direction
and pulse_optimize in {True, None}
and synth_direction != preferred_direction
):
su4_mat_mm = deepcopy(su4_mat)
su4_mat_mm[[1, 2]] = su4_mat_mm[[2, 1]]
su4_mat_mm[:, [1, 2]] = su4_mat_mm[:, [2, 1]]
synth_dag = circuit_to_dag(decomposer2q(su4_mat_mm, basis_fidelity=basis_fidelity))
wires = synth_dag.wires[::-1]
return synth_dag, wires