ENTANGLED-PHOTON VIRTUAL-STATE SPECTROSCOPY

A new form of absorption spectroscopy is introduced in which the energ y levels and matrix elements of virtual-state transitions in a medium are determined by the use of continuous-wave degenerate entangled phot ons without varying their wavelengths. Extractable spectroscopic infor mation is embedded in the entangled-photon absorption cross section wh en measured over a range of entanglement and interbeam-delay times. Th is technique exploits the fundamental quantum interference that arises during the interaction of an entangled quantum state with a quantum s ystem.