def transfer(cov_mat):
cav = apply(t00 * FilterCavity(omega, detuning, length, input_transmission, losses).two_photon_matrix + MM, cov_mat)
cav_losses = 1 - (abs(t00 * FilterCavity(omega, detuning, length, input_transmission, losses).reflectionCoefficient() + tmm)**2 + abs(t00 * FilterCavity(-omega, detuning, length, input_transmission, losses).reflectionCoefficient() + tmm)**2) / 2
cav_vac = cav_losses * State().covariance_matrix
return cav + cav_vac
def variance(self, quadrature_angle = 0, dB = True):
cov_rot = apply(rotation(-quadrature_angle), self.covariance_matrix)
var = np.real(cov_rot[0, 0])
if dB:
return 10 * np.log10(var)
else:
return var
def __init__(self, omega, detuning, length, input_transmission, losses):
self.omega, self.detuning, self.length, self.input_transmission, self.losses = omega, detuning, length, input_transmission, losses
def reflection_coefficient(omega, detuning, input_transmission, losses):
'''gives the transfer function in field amplitude of the cavity'''
epsilon = 2 * losses / (input_transmission**2 + losses)
ksi = 4 * (omega - detuning) * length / (c * (input_transmission**2 + losses))
return( 1 - (2 - epsilon) / (1 + i * ksi) )
one_photon_matrix = np.matrix([[reflection_coefficient(omega, detuning, input_transmission, losses), 0], [0, np.conjugate(reflection_coefficient(-omega, detuning, input_transmission, losses))]])
two_photon_matrix = apply(A2, one_photon_matrix)
LinearOpticalElement.__init__(self, two_photon_matrix)
def __init__(self, squeezing_dB, theta = 0):
r = - 0.5 * np.log(10**(-squeezing_dB/10))
amplitude_squeezed = np.matrix( [[np.exp(-r), 0], [0, np.exp(r)]] )
LinearOpticalElement.__init__(self, apply(rotation(-theta), amplitude_squeezed))
def __init__(self, two_photon_matrix):
transfer = lambda M: apply(two_photon_matrix, M)
OpticalElement.__init__(self, transfer)
self.two_photon_matrix = two_photon_matrix