def m_degeneracy(N, m):
"""Calculate the number of Dicke states |j, m> with same energy.
Parameters
----------
N: int
The number of two-level systems.
m: float
Total spin z-axis projection eigenvalue (proportional to the total
energy).
Returns
-------
degeneracy: int
The m-degeneracy.
"""
jvals = j_vals(N)
maxj = np.max(jvals)
if m < -maxj:
e = "m value is incorrect for this N."
e += " Minimum m value can be {}".format(-maxj)
raise ValueError(e)
degeneracy = N / 2 + 1 - abs(m)
return int(degeneracy)
def m_degeneracy(N, m):
"""Calculate the number of Dicke states :math:`|j, m\\rangle` with
same energy.
Parameters
----------
N: int
The number of two-level systems.
m: float
Total spin z-axis projection eigenvalue (proportional to the total
energy).
Returns
-------
degeneracy: int
The m-degeneracy.
"""
jvals = j_vals(N)
maxj = np.max(jvals)
if m < -maxj:
e = "m value is incorrect for this N."
e += " Minimum m value can be {}".format(-maxj)
raise ValueError(e)
degeneracy = N/2 + 1 - abs(m)
return int(degeneracy)
def test_j_vals(self):
"""
PIQS: Test calculation of j values for given N.
"""
N_list = [1, 2, 3, 4, 7]
j_vals_real = [np.array([0.5]), np.array([0., 1.]),
np.array([0.5, 1.5]),
np.array([0., 1., 2.]),
np.array([0.5, 1.5, 2.5, 3.5])]
j_vals_calc = [j_vals(i) for i in N_list]
for (i, j) in zip(j_vals_calc, j_vals_real):
assert_array_equal(i, j)
def test_j_vals(self):
"""
PIQS: Test calculation of j values for given N.
"""
N_list = [1, 2, 3, 4, 7]
j_vals_real = [np.array([0.5]), np.array([0., 1.]),
np.array([0.5, 1.5]),
np.array([0., 1., 2.]),
np.array([0.5, 1.5, 2.5, 3.5])]
j_vals_calc = [j_vals(i) for i in N_list]
for (i, j) in zip(j_vals_calc, j_vals_real):
assert_array_equal(i, j)
