def expect_oper(self, state, lindbladian, oper):
if lindbladian:
rho = tf_utils.tf_vec_to_dm(state)
else:
rho = tf_utils.tf_state_to_dm(state)
trace = np.trace(np.matmul(rho, oper))
return [[np.real(trace)]] # ,[np.imag(trace)]]
def populations(self, state, lindbladian):
"""
Compute populations from a state or density vector.
Parameters
----------
state: tf.Tensor
State or densitiy vector.
lindbladian: boolean
Specify if conversion to density matrix is needed.
Returns
-------
tf.Tensor
Vector of populations.
"""
if lindbladian:
rho = tf_utils.tf_vec_to_dm(state)
pops = tf.math.real(tf.linalg.diag_part(rho))
return tf.reshape(pops, shape=[pops.shape[0], 1])
else:
return tf.abs(state)**2