Project Summary

This project focuses on time-frequency entangled photon pairs (TF-EPP) as a resource for quantum-enhanced metrology and spectroscopy. The aim of the project is to demonstrate experimentally improved performance in sensing of remote objects and spectroscopy of electronically coupled molecules through the use of TF-EPP. Student participants involved in this project will receive cross-disciplinary training that will enrich their experience and knowledge base, while enhancing career opportunities. 

An interdisciplinary team spanning physics, engineering and chemistry in the Oregon Center for Optical, Molecular, and Quantum Science,proposes to demonstrate that Einstein-Podolsky-Rosen (EPR)-like entanglement of photons in the time-frequency domain can provide a significant quantum advantage in spectroscopy and metrology. Time-frequency entangled photons pairs (EPP) have the property that pairs of photons are tightly correlated in time while being anti-correlated in frequency, such that the sum of the energies of the photon pair is sharply defined. They thus offer the ability to circumvent classical Fourier time-bandwidth limits when employing photon coincidence events, either in detection, as in standard quantum optics, or in two-photon excitation of molecular complexes, as in nonlinear spectroscopy. Time-frequency EPP can thus exploitintrinsically quantum correlations between photon interactions to enable and enhance novel experimental schemes aiming to yield information about physical systems being probed, in a manner not possible in any classical model of light. 


The PIs propose to demonstrate experimentally that entanglement of photons in the time-frequency domain provides a resource bringing a significant quantum advantage in four related novel schemes in metrologyand nonlinearspectroscopyfor probing remote scattering objects and electronically coupled molecular complexes: 1) Quantum illumination (sensing of object presence or absence); 2) Multi-parameter estimation of complementary parameters (estimating the distance and velocity of a reflecting object); 3) Two-photon interferometric nonlinear spectroscopy; and 4) Entangled photon-pair 2D fluorescence spectroscopy.The commonality that unifies the four schemes is the use of broad-band (multi-spectral-mode),time-frequency EPP produced by spontaneous parametric down-conversion (SPDC), coupled with interferometer configurations that exploit quantum interference.  

The advantages of time-frequency EPP for sensing and spectroscopy include: 1) it will provide simultaneous time-frequency information about probed samples that are beyond the time-frequency uncertainty limits of classical optics; 2) it will be effective in the regime of ultralow photon fluxes, thus avoiding optical damage of samples, and in situations where thermal background optical noise is present; and 3) it will reveal population-lifetime line widths of molecular transitions where they are normally obscured by large homogeneous line widths.