posted on 2020-10-26, 17:06authored byJuan P. Villabona-Monsalve, Ryan K. Burdick, Theodore Goodson
Entangled
photons exhibit strong nonclassical frequency and time
correlations simultaneously, which allow them to excite and extract
information about molecules in new ways compared to classical spectroscopy.
In this report, we demonstrate the accessibility of entangled two-photon
absorption (ETPA) as an analytical technique using CW-pumped type-I
degenerate spontaneous parametric down-conversion. We made improvements
to lower the noise, error, and limit of detection of the ETPA experiment.
We prove and quantify frequency entanglement from the experimentally
measured joint frequency spectrum using the Schmidt decomposition.
As evidence of the ETPA process, we found a clear linear dependence
of the ETPA and ETPA-induced fluorescence rates with the entangled
input photon rate for all the studied chromophores. This ETPA experiment
can be used to analyze a wide variety of chromophores of chemical
and biological significance and shows potential for ETPA-induced fluorescence
detection capabilities. As an application of our work, we show that
one may control the population of specific excited states in molecules
with the use of a spatial light modulator in the setup.