Two-photon entanglement generation: different Bell states within the linewidth of phase-matching.
It is shown that for a phase-matched nonlinear process producing entangled states, different Bell states are generated for different mismatch values. In particular, generation of the singlet Bell state is demonstrated within the natural linewidth of collinear frequency-degenerate type-II spontaneous parametric down-conversion (SPDC) without the o-e delay compensation. The singlet state can be filtered out by spectral selection or by the time selection of the two-photon amplitude at the output of a dispersive fibre. The effect is of considerable importance for fibre quantum communication.
Brida
G
G
Chekhova
M V
MV
Genovese
M
M
Krivitsky
L A
LA