Researchers suggest novel way to generate a light source made from entangledphotons LifeAtPurdue
metastable state in helium decays to the ground state by the emission of two energy-time entangled photons with a photon bandwidth equal to the total energy spacing of 20.62 eV.
This results in a pair correlation time in the attosecond regime making these entangled photons a highly suitable source for attosecond pump-probe experiments. The biphoton generation rate from a direct four-photon excitation of helium at 240 nm is calculated and used to assess some feasible schemes to generate these biphotons. Possible applications of entangled biphotons in attosecond timescale experiments, and a discussion of their potential to reach the zeptosecond regime are presented.