def test_bit_flip():
s = ChpSimulator(num_qubits=1)
s.hadamard(0)
s.phase(0)
s.phase(0)
s.hadamard(0)
assert s.measure(0) == MeasureResult(value=True, determined=True)
def test_epr():
s = ChpSimulator(num_qubits=2)
s.hadamard(0)
s.cnot(0, 1)
v1 = s.measure(0)
assert not v1.determined
v2 = s.measure(1)
assert v2.determined
assert v1.value == v2.value
def test_phase_kickback_preserve_s_state():
s = ChpSimulator(num_qubits=2)
# Prepare S state.
s.hadamard(1)
s.phase(1)
# Prepare test input.
s.hadamard(0)
# Kickback.
s.cnot(0, 1)
s.hadamard(1)
s.cnot(0, 1)
s.hadamard(1)
# Check.
s.phase(0)
s.hadamard(0)
assert s.measure(0) == MeasureResult(value=True, determined=True)
s.phase(1)
s.hadamard(1)
assert s.measure(1) == MeasureResult(value=True, determined=True)
def test_phase_kickback_consume_s_state():
s = ChpSimulator(num_qubits=2)
s.hadamard(1)
s.phase(1)
s.hadamard(0)
s.cnot(0, 1)
v1 = s.measure(1)
assert not v1.determined
if v1:
s.phase(0)
s.phase(0)
s.phase(0)
s.hadamard(0)
assert s.measure(0) == MeasureResult(value=True, determined=True)
def test_identity_2():
s = ChpSimulator(num_qubits=2)
assert s.measure(0) == MeasureResult(value=False, determined=True)
assert s.measure(1) == MeasureResult(value=False, determined=True)
def distill(errors: Set[int]) -> str:
sim = ChpSimulator(num_qubits=5)
phasors = [
(0, ),
(1, ),
(2, ),
(0, 1, 2),
(0, 1, 3),
(0, 2, 3),
(1, 2, 3),
]
anc = 4
for e, phasor in enumerate(phasors):
for k in phasor:
sim.hadamard(anc)
sim.cnot(anc, k)
sim.hadamard(anc)
sim.phase(anc)
if e in errors:
sim.phase(anc)
sim.phase(anc)
sim.hadamard(anc)
v = sim.measure(anc)
if v.value:
sim.hadamard(anc)
sim.phase(anc)
sim.phase(anc)
sim.hadamard(anc)
assert not v.determined
if v.value:
for k in phasor:
sim.hadamard(k)
sim.phase(k)
sim.phase(k)
sim.hadamard(k)
sim.phase(3)
sim.phase(3)
sim.phase(3)
sim.hadamard(3)
result = sim.measure(3)
sim.hadamard(3)
sim.phase(3)
checks = [sim.measure(k) for k in range(3)]
assert result.determined
assert all(e.determined for e in checks)
good_result = result.value is False
checks_passed = not any(e.value for e in checks)
if checks_passed:
if good_result:
return 'good'
else:
return 'ERROR'
else:
if good_result:
return 'victim'
else:
return 'caught'
def test_s_state_distillation_low_space():
for _ in range(100):
sim = ChpSimulator(num_qubits=5)
phasors = [
(0, ),
(1, ),
(2, ),
(0, 1, 2),
(0, 1, 3),
(0, 2, 3),
(1, 2, 3),
]
anc = 4
for phasor in phasors:
sim.hadamard(anc)
for k in phasor:
sim.cnot(anc, k)
sim.hadamard(anc)
sim.phase(anc)
sim.hadamard(anc)
v = sim.measure(anc)
assert not v.determined
if v.value:
for k in phasor + (anc, ):
sim.hadamard(k)
sim.phase(k)
sim.phase(k)
sim.hadamard(k)
for k in range(3):
assert sim.measure(k) == MeasureResult(value=False,
determined=True)
sim.phase(3)
sim.hadamard(3)
assert sim.measure(3) == MeasureResult(value=True, determined=True)
def test_s_state_distillation_low_depth():
for _ in range(100):
sim = ChpSimulator(num_qubits=9)
stabilizers = [(0, 1, 2, 3), (0, 1, 4, 5), (0, 2, 4, 6), (1, 2, 4, 7)]
checks = [
{
's': [0],
'q': stabilizers[0]
},
{
's': [1],
'q': stabilizers[1]
},
{
's': [2],
'q': stabilizers[2]
},
]
stabilizer_measurements = []
anc = 8
for stabilizer in stabilizers:
sim.hadamard(anc)
for k in stabilizer:
sim.cnot(anc, k)
sim.hadamard(anc)
v = sim.measure(anc)
assert not v.determined
if v.value:
sim.hadamard(anc)
sim.phase(anc)
sim.phase(anc)
sim.hadamard(anc)
stabilizer_measurements.append(v)
qubit_measurements = []
for k in range(7):
sim.phase(k)
sim.hadamard(k)
qubit_measurements.append(sim.measure(k))
if sum([
int(e.value)
for e in stabilizer_measurements + qubit_measurements
]) & 1:
sim.phase(7)
sim.phase(7)
sim.phase(7)
sim.hadamard(7)
r = sim.measure(7)
assert r == MeasureResult(value=False, determined=True)
for c in checks:
rvs = [int(stabilizer_measurements[k].value) for k in c['s']]
rms = [int(qubit_measurements[k].value) for k in c['q']]
assert sum(rvs + rms) & 1 == 0
def test_kickback_vs_stabilizer():
sim = ChpSimulator(num_qubits=3)
sim.hadamard(2)
sim.cnot(2, 0)
sim.cnot(2, 1)
sim.phase(0)
sim.phase(1)
sim.hadamard(0)
sim.hadamard(1)
sim.hadamard(2)
assert str(sim).strip() == """
-YII
-IYI
+IIX
----
+XIX
+IXX
+YYZ
""".strip().replace('I', '.')
v0 = sim.measure(0, bias=0)
assert str(sim).strip() == """
+XIX
-IYI
+IIX
----
+ZII
+IXX
+ZYY
""".strip().replace('I', '.')
v1 = sim.measure(1, bias=0)
assert str(sim).strip() == """
+XIX
+IXX
+IIX
----
+ZII
+IZI
-ZZZ
""".strip().replace('I', '.')
v2 = sim.measure(2, bias=0)
assert str(sim).strip() == """
+XIX
+IXX
+IIX
----
+ZII
+IZI
-ZZZ
""".strip().replace('I', '.')
assert v0 == MeasureResult(value=False, determined=False)
assert v1 == MeasureResult(value=False, determined=False)
assert v2 == MeasureResult(value=True, determined=True)