def test_save_load(self, tmpdir, tol):
"""test saving and loading of squeezoing factors"""
factors_in = so.generate_squeeze_factors(4)
so.save_squeeze_factors(factors_in, directory=str(tmpdir))
factors_out = so.load_squeeze_factors(4, directory=str(tmpdir))
assert np.allclose(factors_out, SQUEEZE_FACTOR_4, atol=tol, rtol=0)
def test_save_load_squeeze_factors(self):
factors_in = so.generate_squeeze_factors(4)
so.save_squeeze_factors(factors_in, directory="./")
factors_out = so.load_squeeze_factors(4, directory="./")
self.assertAllAlmostEqual(factors_out,
squeeze_factor_4,
delta=self.tol)
def squeezing(r, theta, trunc, save=False, directory=None):
r"""The squeezing operator :math:`S(re^{i\theta})`.
Args:
r (float): the magnitude of the squeezing in the
x direction
theta (float): the squeezing angle
trunc (int): the Fock cutoff
"""
# pylint: disable=duplicate-code
if r == 0:
# return the identity
ret = np.eye(trunc, dtype=def_type)
else:
# broadcast the index arrays
dim_array = np.arange(trunc)
N = dim_array.reshape((-1, 1, 1))
n = dim_array.reshape((1, -1, 1))
k = dim_array.reshape((1, 1, -1))
try:
prefac = so.load_squeeze_factors(trunc, directory)
except FileNotFoundError:
prefac = so.generate_squeeze_factors(trunc)
if save:
so.save_bs_factors(prefac, directory)
# we only perform the sum when n+N is divisible by 2
# in which case we sum 0 <= k <= min(N,n)
# mask = np.logical_and((n+N)%2 == 0, k <= np.minimum(N, n))
mask = np.logical_and((n + N) % 2 == 0, k <= np.minimum(N, n))
# perform the summation over k
scale = mask * np.power(sinh(r) / 2,
mask * (N + n - 2 * k) / 2) / (cosh(r)**(
(N + n + 1) / 2))
ph = exp(1j * theta * (N - n) / 2)
ret = np.sum(scale * ph * prefac, axis=-1)
return ret