Pete Shadbolt 8 anni fa
parent
commit
329cbe70e3
2 ha cambiato i file con 29 aggiunte e 27 eliminazioni
  1. +28
    -26
      abp/graphstate.py
  2. +1
    -1
      tests/test_measurement.py

+ 28
- 26
abp/graphstate.py Vedi File

@@ -9,6 +9,7 @@ import json, random
import qi, clifford, util
from stabilizer import Stabilizer


class GraphState(object):

"""
@@ -31,9 +32,10 @@ class GraphState(object):
self.adj = data.adj.copy()
self.node = data.node.copy()
for key, value in self.node.items():
self.node[key]["vop"] = data.node[key].get("vop", clifford.identity)
self.node[key]["vop"] = data.node[
key].get("vop", clifford.identity)
except AttributeError:
try:
try:
# Provided with a list of node names?
for n in data:
self._add_node(n, vop=vop)
@@ -46,7 +48,6 @@ class GraphState(object):
""" Add a node """
self._add_node(self, *args, **kwargs)


def _del_node(self, node):
""" Remove a node. TODO: this is a hack right now! """
if not node in self.node:
@@ -56,7 +57,6 @@ class GraphState(object):
del self.adj[k][node]
del self.adj[node]


def _add_node(self, node, **kwargs):
""" Add a node. By default, nodes are initialized with ``vop=``:math:`I`, i.e. they are in the :math:`|+\\rangle` state.

@@ -78,19 +78,21 @@ class GraphState(object):
default = kwargs.get("default", "identity")
self.adj[node] = {}
self.node[node] = {}
kwargs["vop"] = clifford.by_name[str(kwargs.get("vop", "identity"))] #TODO: ugly
kwargs["vop"] = clifford.by_name[
str(kwargs.get("vop", "identity"))] # TODO: ugly
self.node[node].update(kwargs)

def add_qubit(self, name, **kwargs):
""" Add a qubit to the state.
""" Add a qubit to the state.

:param name: The name of the node, e.g. ``9``, ``start``.
:type name: Any hashable type
:param kwargs: Any extra node attributes

By default, qubits are initialized in the :math:`|0\\rangle` state. Provide the optional ``vop`` argument to set the initial state.
By default, qubits are initialized in the :math:`|0\\rangle` state. Provide the optional ``vop`` argument to set the initial state.
"""
kwargs["vop"] = clifford.by_name[str(kwargs.get("vop", "hadamard"))] #TODO: ugly
kwargs["vop"] = clifford.by_name[
str(kwargs.get("vop", "hadamard"))] # TODO: ugly
self._add_node(name, **kwargs)

def act_circuit(self, circuit):
@@ -224,14 +226,14 @@ class GraphState(object):
:type basis: :math:`\in` ``{"px", "py", "pz"}``
:param force: Forces the measurement outcome.
:type force: boolean
:param detail: Get detailed information.
:param detail: Get detailed information.
:type detail: boolean
Measurements in quantum mechanics are probabilistic. If you want to force a particular outcome :math:`\in\{0, 1\}`, use ``force``.

You can get more information by setting ``detail=True``, in which case ``measure()`` returns a dictionary with the following keys:

- ``outcome``: the measurement outcome.
- ``outcome``: the measurement outcome.
- ``determinate``: indicates whether the outcome was determinate or random. For example, measuring :math:`|0\\rangle` in :math:`\sigma_x` always gives a deterministic outcome. ``determinate`` is overridden by ``force`` -- forced outcomes are always determinate.
- ``conjugated_basis``: The index of the measurement operator, rotated by the vertex operator of the measured node, i.e. :math:`U_\\text{vop} \sigma_m U_\\text{vop}^\dagger`.
- ``phase``: The phase of the cojugated basis, :math:`\pm 1`.
@@ -263,8 +265,8 @@ class GraphState(object):
result = not result

if detail:
return {"outcome": int(result),
"determinate": (determinate or force!=None),
return {"outcome": int(result),
"determinate": (determinate or force != None),
"conjugated_basis": basis,
"phase": phase,
"node": node,
@@ -312,23 +314,24 @@ class GraphState(object):

def measure_sequence(self, measurements, forces=None, detail=False):
""" Measures a sequence of Paulis
:param measurements: The sequence of measurements to be made, in the form [(node, basis), ...]
:type force: list of tuples
:param force: Measurements in quantum mechanics are probabilistic. If you want to force a particular outcome, use the ``force``. List outcome force values in same order as measurements
:type force: list
:param detail: Provide detailed information
:type detail: boolean
"""
forces = forces if forces != None else [random.choice([0, 1]) for i in range(len(measurements))]
forces = forces if forces != None else [
random.choice([0, 1]) for i in range(len(measurements))]
measurements = zip(measurements, forces)
results = []
for (node, basis), force in measurements:
result = self.measure(node, basis, force, detail)
results += [result]
return results
def _toggle_edges(self, a, b):
""" Toggle edges between vertex sets a and b """
# TODO: i'm pretty sure this is just a single-line it.combinations or
@@ -352,7 +355,7 @@ class GraphState(object):
else:
friend = next(self.adj[node].iterkeys())
else:
assert friend in self.adj[node].keys() # TODO: unnecessary assert
assert friend in self.adj[node].keys() # TODO: unnecessary assert

# Update the VOPs. TODO: pretty ugly
if result:
@@ -452,7 +455,7 @@ class GraphState(object):
return {"node": self.node, "adj": self.adj}

def from_json(self, data):
""" Construct the graph from JSON data
""" Construct the graph from JSON data
:param data: JSON data to be read.
"""
self.node = data["node"]
@@ -482,17 +485,17 @@ class GraphState(object):
return state

def to_stabilizer(self):
"""
"""
Get the stabilizer representation of the state::

>>> print g.to_stabilizer()
0 1 2 3 100 200
------------------------------
X Z Z X
Z X Z
Z Z X
- Z Z
X Z
X Z Z X
Z X Z
Z Z X
- Z Z
X Z
Z X

"""
@@ -509,4 +512,3 @@ class GraphState(object):
g.adj = self.adj.copy()
g.deterministic = self.deterministic
return g


+ 1
- 1
tests/test_measurement.py Vedi File

@@ -60,6 +60,7 @@ def test_projection():
g.measure(0, "pz", 1)
assert np.allclose(g.to_state_vector().state, qi.one)


def test_measure_sequence():
""" Simple test of measurement sequences """
g = GraphState(2, vop="identity")
@@ -68,4 +69,3 @@ def test_measure_sequence():
assert len(g.edgelist()) == 0
assert g.node[1]["vop"] == clifford.pz



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