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Add state equality checking, global phase fixing.

master
Pete Shadbolt 8 anni fa
parent
commit
d372ec8531
7 ha cambiato i file con 62 aggiunte e 31 eliminazioni
  1. +4
    -13
      abp/clifford.py
  2. +18
    -1
      abp/qi.py
  3. +9
    -13
      tests/test_against_circuit_model.py
  4. +1
    -1
      tests/test_cphase_against_anders.py
  5. +1
    -1
      tests/test_cphase_table.py
  6. +1
    -1
      tests/test_normalize_global_phase.py
  7. +28
    -1
      tests/test_qi_circuit_model.py

+ 4
- 13
abp/clifford.py Vedi File

@@ -26,26 +26,17 @@ def get_name(i):

def find_clifford(needle, haystack):
""" Find the index of a given u within a list of unitaries, up to a global phase """
needle = normalize_global_phase(needle)
needle = qi.normalize_global_phase(needle)
for i, t in enumerate(haystack):
if np.allclose(t, needle):
return i
raise IndexError


def normalize_global_phase(m):
""" Normalize the global phase of a matrix """
v = (x for x in m.flatten() if np.abs(x) > 0.001).next()
phase = np.arctan2(v.imag, v.real) % np.pi
rot = np.exp(-1j * phase)
return rot * m if rot * v > 0 else -rot * m


def find_cz(bond, c1, c2, commuters, state_table, ab_cz_table):
""" Find the output of a CZ operation """
# Figure out the target state
target = qi.cz.dot(state_table[bond, c1, c2])
target = normalize_global_phase(target)
target = qi.normalize_global_phase(target)

# Choose the sets to search over
s1 = commuters if c1 in commuters else xrange(24)
@@ -64,7 +55,7 @@ def compose_u(decomposition):
""" Get the unitary representation of a particular decomposition """
matrices = ({"x": qi.sqx, "z": qi.msqz}[c] for c in decomposition)
output = reduce(np.dot, matrices, np.eye(2, dtype=complex))
return normalize_global_phase(output)
return qi.normalize_global_phase(output)


def get_unitaries():
@@ -96,7 +87,7 @@ def get_state_table(unitaries):
for bond, i, j in tqdm(params, desc="Building state table"):
state = qi.bond if bond else qi.nobond
kp = np.kron(unitaries[i], unitaries[j])
state_table[bond, i, j, :] = normalize_global_phase(
state_table[bond, i, j, :] = qi.normalize_global_phase(
np.dot(kp, state).T)
return state_table



+ 18
- 1
abp/qi.py Vedi File

@@ -3,6 +3,7 @@

"""
Exposes a few basic QI operators
And a circuit-model simulator
"""

import numpy as np
@@ -20,7 +21,7 @@ id = np.array(np.eye(2, dtype=complex))
px = np.array([[0, 1], [1, 0]], dtype=complex)
py = np.array([[0, -1j], [1j, 0]], dtype=complex)
pz = np.array([[1, 0], [0, -1]], dtype=complex)
ha = np.array([[1, 1], [1, -1]], dtype=complex) * ir2
ha = hadamard = np.array([[1, 1], [1, -1]], dtype=complex) * ir2
ph = np.array([[1, 0], [0, 1j]], dtype=complex)
t = np.array([[1, 0], [0, np.exp(1j*np.pi/4)]], dtype=complex)

@@ -48,6 +49,15 @@ by_name = dict(zip(names, common_us))

paulis = px, py, pz


def normalize_global_phase(m):
""" Normalize the global phase of a matrix """
v = (x for x in m.flatten() if np.abs(x) > 0.001).next()
phase = np.arctan2(v.imag, v.real) % np.pi
rot = np.exp(-1j * phase)
return rot * m if rot * v > 0 else -rot * m


class CircuitModel(object):
def __init__(self, nqubits):
self.nqubits = nqubits
@@ -84,6 +94,13 @@ class CircuitModel(object):
output[i ^ where] += v*u[not q, q]
self.state = output

def __eq__(self, other):
""" Check whether two quantum states are the same or not
UP TO A GLOBAL PHASE """
a = normalize_global_phase(self.state)
b = normalize_global_phase(other.state)
return np.allclose(a, b)


def __str__(self):
s = ""


+ 9
- 13
tests/test_against_circuit_model.py Vedi File

@@ -14,7 +14,7 @@ def test_hadamard_only_multiqubit():
g.act_hadamard(i)
c.act_hadamard(i)

assert np.allclose(g.to_state_vector().state, c.state)
assert g.to_state_vector() == c

for i in range(100):
a, b = np.random.randint(0, n-1, 2)
@@ -22,9 +22,7 @@ def test_hadamard_only_multiqubit():
g.act_cz(a, b)
c.act_cz(a, b)

s1 = clifford.normalize_global_phase(g.to_state_vector().state)
s2 = clifford.normalize_global_phase(c.state)
assert np.allclose(s1, s2)
assert g.to_state_vector() == c


def test_all_multiqubit():
@@ -34,13 +32,13 @@ def test_all_multiqubit():
c = CircuitModel(n)

for i in range(10):
i = np.random.randint(0, n-1)
j = np.random.randint(0, 24)
print i, j
g.act_local_rotation(i, j)
c.act_local_rotation(i, clifford.unitaries[j])
qubit = np.random.randint(0, n-1)
rotation = np.random.randint(0, 24-1)
g.act_local_rotation(qubit, rotation)
c.act_local_rotation(qubit, clifford.unitaries[rotation])

assert np.allclose(g.to_state_vector().state, c.state)

assert g.to_state_vector() == c

#for i in range(100):
#a, b = np.random.randint(0, n-1, 2)
@@ -48,7 +46,5 @@ def test_all_multiqubit():
#g.act_cz(a, b)
#c.act_cz(a, b)

#s1 = clifford.normalize_global_phase(g.to_state_vector().state)
#s2 = clifford.normalize_global_phase(c.state)
#assert np.allclose(s1, s2)
assert g.to_state_vector() == c


+ 1
- 1
tests/test_cphase_against_anders.py Vedi File

@@ -30,7 +30,7 @@ def test_cz_table():

# Go and compute the output
computed_output = np.dot(qi.cz, input_state)
computed_output = clifford.normalize_global_phase(computed_output)
computed_output = qi.normalize_global_phase(computed_output)

# Now look up the answer in the table
bondp, c1p, c2p = ab_cz_table[bond, c1, c2]


+ 1
- 1
tests/test_cphase_table.py Vedi File

@@ -15,7 +15,7 @@ def test_cz_table():

# Go and compute the output
computed_output = np.dot(qi.cz, input_state)
computed_output = clifford.normalize_global_phase(computed_output)
computed_output = qi.normalize_global_phase(computed_output)

# Now look up the answer in the table
bondp, c1p, c2p = clifford.cz_table[bond, c1, c2]


+ 1
- 1
tests/test_normalize_global_phase.py Vedi File

@@ -7,5 +7,5 @@ def test_normalize_global_phase():
u = qi.pz
phase = np.random.uniform(0, 2*np.pi)
m = np.exp(1j*phase) * u
normalized = clifford.normalize_global_phase(m)
normalized = qi.normalize_global_phase(m)
assert np.allclose(normalized, u)

+ 28
- 1
tests/test_qi_circuit_model.py Vedi File

@@ -1,11 +1,38 @@
import numpy as np
from abp import qi

def _test_init():
def test_init():
""" Can you initialize some qubits """
psi = qi.CircuitModel(5)
assert psi.d == 32

def test_single_qubit_stuff():
""" Try some sensible single-qubit things """
psi = qi.CircuitModel(2)
psi.act_local_rotation(0, qi.px)
assert np.allclose(psi.state[1], 1)
psi.act_local_rotation(0, qi.px)
assert np.allclose(psi.state[0], 1)
psi.act_local_rotation(0, qi.pz)


def test_more_single_qubit_stuff():
""" Try some sensible single-qubit things """
psi = qi.CircuitModel(2)
psi.act_local_rotation(0, qi.px)
psi.act_local_rotation(1, qi.px)
psi.act_cz(0, 1)

def test_equality():
""" Test that equality succeeds / fails as desired """
a = qi.CircuitModel(2)
b = qi.CircuitModel(2)
assert a == b
a.act_local_rotation(0, qi.px)
assert a != b



def test_hadamard():
""" What does CZ do ? """
psi = qi.CircuitModel(3)


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