content: import numpy as np
  import qutip
  
  b = qutip.Bloch()
  th = np.linspace(0, 2*np.pi, 20)
  
  xp = np.cos(th)
  yp = np.sin(th)
  zp = np.zeros(20)
  
  xz = np.zeros(20)
  yz = np.sin(th)
  zz = np.cos(th)
  
  b.add_points([xp, yp, zp])
  b.add_points([xz, yz, zz])
  b.show()
  