Quantum Interference in Two-Photon Absorption: Non - Level Crossing Studies in the Atomic Spectroscopy of Strontium.

李院院, Jintao Bai, Li Li +2 more

Bahaa E. A. Saleh, Bradley M. Jost, Hong-Bing Fei +1 more

A new form of absorption spectroscopy is introduced in which the energy levels and matrix elements of virtual-state transitions in a medium are determined by the use of continuous-wave degenerate entangled photons without varying their wavelengths. Extractable spectroscopic information is embedded in the entangled-photon absorption cross section when measured over a range of entanglement and interbeam-delay times. This technique exploits the fundamental quantum interference that arises during the interaction of an entangled quantum state with a quantum system.

Gerald J. Diebold, R. B. Stewart

A. Anikin, Timur A. Zalialiutdinov, Dmitry A. Solovyev

In the present paper, we consider nonresonant corrections to $2s\text{\ensuremath{-}}ns/nd$ transition frequencies in hydrogen for the experiments based on two-photon spectroscopy. A detailed study of angular correlations of quantum interference effects within the framework of rigorous quantum electrodynamics is given. Closed expressions for the resonant two-photon-scattering cross sections on an atomic level with dependence on all atomic quantum numbers including fine and hyperfine structure are derived. These expressions are applied for the description of experiments based on two-photon spectroscopy with fixing of incident (outgoing) photon polarizations. We demonstrate that, for certain experimental geometries, nonresonant corrections could be significant for the determination of Rydberg constant and proton charge radius.

Muhammad Aslam Baig, M. Yaseen, Ali Nadeem +2 more

Dong-Ik Lee, Theodore G. Goodson III

By utilizing entanglement property of photons the entangled two-photon absorption (ETPA) effect of an organic material, porphyrin dendrimer, is demonstrated through the comparison of the property of entangled photons to the property of quantum-correlated photons. The ETPA showed a cross-section 31 orders of magnitude higher than the cross-section of the classical two-photon absorption (TPA). This high cross-section is comparable to the cross-section of the resonant single-photon absorption. The entangled absorption effect is compared to the correlated TPA effect to determine the degree of correlation between the entangled and quantum correlated photon pairs. The experimental data describe the different degree of correlation of the non-entangled and entangled photon pairs by demonstrating linear and nonlinear relationship of the absorbed photon flux to the input photon flux. The linearity of the ETPA is an interesting quantum effect because the two-photon absorption is an inherently nonlinear process. Virtual state spectroscopy is also demonstrated as a novel spectroscopic method to investigate the properties of the virtual state from non-monotonic behavior of the cross-section which is represented by controlling temporal property of the entanglement. These results from the quantum spectroscopy methods show a unique quantum property which is not feasible to detect using classical methods.