def apply_channel(self, action: Any, axes: Sequence[int]) -> bool:
"""Apply channel to state.
Args:
action: The value with a channel to apply.
axes: The axes on which to apply the channel.
Returns:
True if the action succeeded.
"""
result = protocols.apply_channel(
action,
args=protocols.ApplyChannelArgs(
target_tensor=self._density_matrix,
out_buffer=self._buffer[0],
auxiliary_buffer0=self._buffer[1],
auxiliary_buffer1=self._buffer[2],
left_axes=axes,
right_axes=[e + len(self._qid_shape) for e in axes],
),
default=None,
)
if result is None:
return False
for i in range(len(self._buffer)):
if result is self._buffer[i]:
self._buffer[i] = self._density_matrix
self._density_matrix = result
return True
def _apply_op_channel(self, op: ops.Operation, state: _StateAndBuffers,
indices: List[int]) -> None:
"""Apply channel to state."""
result = protocols.apply_channel(
op,
args=protocols.ApplyChannelArgs(
target_tensor=state.tensor,
out_buffer=state.buffers[0],
auxiliary_buffer0=state.buffers[1],
auxiliary_buffer1=state.buffers[2],
left_axes=indices,
right_axes=[e + state.num_qubits for e in indices]))
for i in range(3):
if result is state.buffers[i]:
state.buffers[i] = state.tensor
state.tensor = result
def _strat_apply_channel_to_state(action: Any, args: ActOnDensityMatrixArgs,
qubits: Sequence['cirq.Qid']) -> bool:
"""Apply channel to state."""
axes = args.get_axes(qubits)
result = protocols.apply_channel(
action,
args=protocols.ApplyChannelArgs(
target_tensor=args.target_tensor,
out_buffer=args.available_buffer[0],
auxiliary_buffer0=args.available_buffer[1],
auxiliary_buffer1=args.available_buffer[2],
left_axes=axes,
right_axes=[e + len(args.qid_shape) for e in axes],
),
default=None,
)
if result is None:
return NotImplemented
for i in range(3):
if result is args.available_buffer[i]:
args.available_buffer[i] = args.target_tensor
args.target_tensor = result
return True
