/
zeros_sampler.py
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/
zeros_sampler.py
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# Copyright 2020 The Cirq Developers
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import abc
from typing import Dict, List, TYPE_CHECKING
import numpy as np
from cirq import devices, work, study, protocols
if TYPE_CHECKING:
import cirq
class ZerosSampler(work.Sampler, metaclass=abc.ABCMeta):
"""A dummy sampler for testing. Immediately returns zeroes."""
def __init__(self, device: devices.Device = None):
"""Construct a sampler that returns 0 for all measurements.
Args:
device: A device against which to validate the circuit. If None,
no validation will be done.
"""
self.device = device
def run_sweep(
self,
program: 'cirq.Circuit',
params: study.Sweepable,
repetitions: int = 1,
) -> List[study.Result]:
"""Samples circuit as if every measurement resulted in zero.
Args:
program: The circuit to sample from.
params: Parameters to run with the program.
repetitions: The number of times to sample.
Returns:
Result list for this run; one for each possible parameter
resolver.
Raises:
ValueError if this sampler has a device and the circuit is not
valid for the device.
"""
if self.device:
self.device.validate_circuit(program)
measurements = {} # type: Dict[str, np.ndarray]
for op in program.all_operations():
key = protocols.measurement_key(op, default=None)
if key is not None:
measurements[key] = np.zeros((repetitions, len(op.qubits)), dtype=int)
return [
study.Result(params=param_resolver, measurements=measurements)
for param_resolver in study.to_resolvers(params)
]