density matrix: [[[[  2.71066432e-01  -1.07856040e-02   9.07814858e-03  -2.60324510e-01
     -2.14321077e-09]
   [ -1.07856040e-02   2.97099774e-01   9.52322235e-02  -1.38848431e-02
     -1.97357976e-01]
   [  9.07814858e-03   9.52322235e-02   1.42730494e-01   4.53909162e-03
     -4.31946315e-02]
   [ -2.60324510e-01  -1.38848431e-02   4.53909162e-03   2.95736883e-01
      4.02728377e-02]
   [ -2.14321077e-09  -1.97357976e-01  -4.31946315e-02   4.02728377e-02
      2.35328545e-01]]]]