abp/tests/test_measurement.py

import numpy as np
from abp import GraphState
from abp import qi, clifford
from anders_briegel import graphsim
from tqdm import tqdm
import random

REPEATS = 100000
LOCAL_ROTATION = 0
CZ = 1
MEASURE = 2

def test_single_qubit_measurements():
    """ Various simple tests of measurements """

    # Test that measuring |0> in Z gives 0
    g = GraphState([0])
    assert g.measure(0, "pz") == 0, "Measuring |0> in Z gives 0"

    # Test that measuring |1> in Z gives 1
    g = GraphState([0])
    g.act_local_rotation(0, "px")
    assert g.measure(0, "pz") == 1, "Measuring |1> in Z gives 1"

    # Test that measuring |+> in X gives 0
    g = GraphState([0])
    g.act_local_rotation(0, "hadamard")
    assert g.measure(0, "px") == 0
    assert g.measure(0, "px") == 0, "Measuring |+> in X gives 0"
    g.act_local_rotation(0, "pz")
    assert g.measure(0, "px") == 1, "Measuring |-> in X gives 1"

def test_random_outcomes():
    """ Testing random behaviour """
    ones = 0
    for i in range(1000):
        g = GraphState([0])
        g.act_local_rotation(0, "hadamard")
        ones += g.measure(0, "pz")
    assert 400 < ones < 600, "This is a probabilistic test!"

def test_projection():
    """ Test that projection works correctly """
    g = GraphState([0])
    g.act_local_rotation(0, "hadamard")
    g.measure(0, "pz", 0)
    assert np.allclose(g.to_state_vector().state, qi.zero)

def test_another_projection():
    """ This one fails at the moment """
    g = GraphState([0])
    g.act_local_rotation(0, "hadamard")
    g.measure(0, "pz", 1)
    assert np.allclose(g.to_state_vector().state, qi.one)

def test_z_measurement_against_ab():
    for i in range(10):
        a = graphsim.GraphRegister(1)
        b = GraphState()
        b.add_node(0)
        #print a.measure(0, graphsim.lco_Z) 
        #print b.measure(0, "pz")

def test_all(N=20):
    """ Test everything"""

    clifford.use_old_cz()

    a = graphsim.GraphRegister(N)
    b = GraphState(range(N))
    previous_state, previous_cz = None, None
    for i in tqdm(range(REPEATS), desc="Testing all gates against Anders and Briegel"):
        which = random.choice([LOCAL_ROTATION, CZ, MEASURE])
        if which == LOCAL_ROTATION:
            j = random.randint(0, N-1)
            u = random.randint(0, 23)
            a.local_op(j, graphsim.LocCliffOp(u))
            b.act_local_rotation(j, u)
        elif which == CZ:
            q = random.randint(0, N-2)
            if a!=b:
                a.cphase(q, q+1)
                b.act_cz(q, q+1)
        else:
            pass
            #q = random.randint(0, N-2)
            #m = random.choice(["px", "py", "pz"])
            #a.measure(q, m)
            #b.measure(q, mm)
        assert a.to_json() == b.to_json()