def as_clifford(self):
"""
If this circuit is composed entirely of Clifford operators, converts it
to a :class:`qecc.Clifford` instance representing the action of the
entire circuit. If the circuit is not entirely Clifford gates, this method
raises a :obj:`RuntimeError`.
"""
if not all(loc.is_clifford for loc in self):
raise RuntimeError('All locations must be Clifford gates in order to represent a circuit as a Clifford operator.')
nq = self.nq
return reduce(mul, (loc.as_clifford(nq) for loc in reversed(self)), cc.eye_c(nq))
def as_clifford(self):
"""
If this circuit is composed entirely of Clifford operators, converts it
to a :class:`qecc.Clifford` instance representing the action of the
entire circuit. If the circuit is not entirely Clifford gates, this method
raises a :obj:`RuntimeError`.
"""
if not all(loc.is_clifford for loc in self):
raise RuntimeError(
'All locations must be Clifford gates in order to represent a circuit as a Clifford operator.'
)
nq = self.nq
return reduce(mul, (loc.as_clifford(nq) for loc in reversed(self)),
cc.eye_c(nq))
def as_clifford(self, nq):
return cc.eye_c(nq)
def as_clifford(self, nq):
return cc.eye_c(nq)
class Location(object):
"""
Represents a gate, wait, measurement or preparation location in a
circuit.
Note that currently, only gate locations are implemented.
:param kind: The kind of location to be created. Each kind is an
abbreviation drawn from ``Location.KIND_NAMES``, or is the index in
``Location.KIND_NAMES`` corresponding to the desired location kind.
:type kind: int or str
:param qubits: Indicies of the qubits on which this location acts.
:type qubits: tuple of ints.
"""
## PRIVATE CLASS CONSTANTS ##
_CLIFFORD_GATE_KINDS = [
'I', 'X', 'Y', 'Z', 'H', 'R_pi4', 'CNOT', 'CZ', 'SWAP'
]
_CLIFFORD_GATE_FUNCS = {
'I': lambda nq, idx: cc.eye_c(nq),
'X': lambda nq, idx: pc.elem_gen(nq, idx, 'X').as_clifford(),
'Y': lambda nq, idx: pc.elem_gen(nq, idx, 'Y').as_clifford(),
'Z': lambda nq, idx: pc.elem_gen(nq, idx, 'Z').as_clifford(),
'H': cc.hadamard,
'R_pi4': cc.phase,
'CNOT': cc.cnot,
'CZ': cc.cz,
'SWAP': cc.swap
}
_QCVIEWER_NAMES = {
'I': 'I', # This one is implemented by a gate definition
# included by Circuit.as_qcviewer().
'X': 'X',
'Y': 'Y',
'Z': 'Z',
'H': 'H',
'R_pi4': 'P',
'CNOT': 'tof',
'CZ': 'Z',
'SWAP': 'swap'
}
## PUBLIC CLASS CONSTANTS ##
#: Names of the kinds of locations used by QuaEC.
KIND_NAMES = sum([_CLIFFORD_GATE_KINDS], [])
## INITIALIZER ##
def __init__(self, kind, *qubits):
if isinstance(kind, int):
self._kind = kind
elif isinstance(kind, str):
self._kind = self.KIND_NAMES.index(kind)
else:
raise TypeError("Location kind must be an int or str.")
#if not all(isinstance(q, int) for q in qubits):
# raise TypeError('Qubit indices must be integers. Got {} instead, which is of type {}.'.format(
# *(iter((q, type(q)) for q in qubits if not isinstance(q, int)).next())
# ))
try:
self._qubits = tuple(map(int, qubits))
except TypeError as e:
raise TypeError('Qubit integers must be int-like.')
self._is_clifford = bool(self.kind in self._CLIFFORD_GATE_KINDS)
## REPRESENTATION METHODS ##
def __str__(self):
return " {:<4} {}".format(self.kind,
' '.join(map(str, self.qubits)))
def __repr__(self):
return "<{} Location on qubits {}>".format(self.kind, self.qubits)
def __hash__(self):
return hash((self._kind, ) + self.qubits)
## IMPORT METHODS ##
@staticmethod
def from_quasm(source):
"""
Returns a :class:`qecc.Location` initialized from a QuASM-formatted line.
:type str source: A line of QuASM code specifying a location.
:rtype: :class:`qecc.Location`
:returns: The location represented by the given QuASM source.
"""
parts = source.split()
return Location(parts[0], *map(int, parts[1:]))
## PROPERTIES ##
@property
def kind(self):
"""
Returns a string defining which kind of location this instance
represents. Guaranteed to be a string that is an element of
``Location.KIND_NAMES``.
"""
return self.KIND_NAMES[self._kind]
@property
def qubits(self):
"""
Returns a tuple of ints describing which qubits this location acts upon.
"""
return self._qubits
@property
def nq(self):
"""
Returns the number of qubits in the smallest circuit that can contain
this location without relabeling qubits. For a :class:`qecc.Location`
``loc``, this property is defined as ``1 + max(loc.nq)``.
"""
return 1 + max(self.qubits)
@property
def is_clifford(self):
"""
Returns ``True`` if and only if this location represents a gate drawn
from the Clifford group.
"""
return self._is_clifford
@property
def wt(self):
"""
Returns the number of qubits on which this location acts.
"""
return len(self.qubits)
## SIMULATION METHODS ##
def as_clifford(self, nq=None):
"""
If this location represents a Clifford gate, returns the action of that
gate. Otherwise, a :obj:`RuntimeError` is raised.
:param int nq: Specifies how many qubits to represent this location as
acting upon. If not specified, defaults to the value of the ``nq``
property.
:rtype: :class:`qecc.Clifford`
"""
if not self.is_clifford:
raise RuntimeError("Location must be a Clifford gate.")
else:
if nq is None:
nq = self.nq
elif nq < self.nq:
raise ValueError(
'nq must be greater than or equal to the nq property.')
return self._CLIFFORD_GATE_FUNCS[self.kind](nq, *self.qubits)
## EXPORT METHODS ##
def as_qcviewer(self, qubit_names=None):
"""
Returns a representation of this location in a format suitable for
inclusion in a QCViewer file.
:param qubit_names: If specified, the given aliases will be used for the
qubits involved in this location when exporting to QCViewer.
Defaults to "q1", "q2", etc.
:rtype: str
Note that the identity (or "wait") location requires the following to be
added to QCViewer's ``gateLib``::
NAME wait
DRAWNAME "1"
SYMBOL I
1 , 0
0 , 1
"""
# FIXME: link to QCViewer in the docstring here.
return ' {gatename} {gatespec}\n'.format(
gatename=self._QCVIEWER_NAMES[self.kind],
gatespec=qubits_str(self.qubits, qubit_names),
)
## OTHER METHODS ##
def relabel_qubits(self, relabel_dict):
"""
Returns a new location related to this one by a relabeling of the
qubits. The relabelings are to be indicated by a dictionary that
specifies what each qubit index is to be mapped to.
>>> import qecc as q
>>> loc = q.Location('CNOT', 0, 1)
>>> print loc
CNOT 0 1
>>> print loc.relabel_qubits({1: 2})
CNOT 0 2
:param dict relabel_dict: If `i` is a key of `relabel_dict`, then qubit
`i` will be replaced by `relabel_dict[i]` in the returned location.
:rtype: :class:`qecc.Location`
:returns: A new location with the qubits relabeled as
specified by `relabel_dict`.
"""
return Location(
self.kind,
*tuple(relabel_dict[i] if i in relabel_dict else i
for i in self.qubits))
