def calculate_and_save():
energies = np.empty((B_list.size, 2**number_of_spins))
for i,B in enumerate(B_list):
print i
calc = ising_calculator_AFM(number_of_spins, alpha, B)
energies[i,:] = calc.find_energies()
np.save('energy_array', energies)
def calculate_and_save():
energies = np.empty((B_list.size, 2**number_of_spins))
for i, B in enumerate(B_list):
print i
calc = ising_calculator_AFM(number_of_spins, alpha, B)
energies[i, :] = calc.find_energies()
np.save('energy_array', energies)
def apply_dephasing(number_of_spins, alpha, B,fm_str = 'AFM',kT = 0.0):
'''
takes number of spins, alpha, and the magnetic field and returns the
hamiltonian along with its ground state and the dephased ground state
choose fm_str = 'FM' for ferromagnetic interaction, and 'AFM' for anti-ferromagnetic
'''
if fm_str == 'FM':
calc = ising_calculator_FM(number_of_spins, alpha, B)
elif fm_str == 'AFM':
calc = ising_calculator_AFM(number_of_spins, alpha, B)
H = calc.get_H()
if kT == 0.0:
energy,groundstate = H.groundstate()
dm_groundstate = ket2dm(groundstate)
else:
Hdata = H.data.todense()
arr_mp = mp.matrix(-Hdata /kT)
exp_mp = mp.expm(arr_mp)
trace = np.array(exp_mp.tolist()).trace()
normalized_mp = exp_mp / trace
normalized_np = np.array(normalized_mp.tolist(), dtype = np.complex)
dm_groundstate = Qobj(normalized_np, dims = 2 * [number_of_spins*[2]])
dephased = do_dephasing_dm(dm_groundstate, number_of_spins)
return H, dm_groundstate, dephased