Virtual-state spectroscopy with frequency-tailored intense entangled beams

Abstract

In this contribution we analyze virtual-state spectroscopy -a unique tool for extracting information about the virtual states that contribute to the two-photon excitation of an absorbing medium -as implemented by means of intense entangled beams with tunable spectral correlations. We provide a thorough description of all contributing terms (classical and quantum) in the two-photon absorption signal, as well as the limits imposed by the power of the pump that produces the entangled beams on the observability of the spectral lines of the virtual transitions. We find that virtual-state spectroscopy may be implemented with entangled twin beams carrying up to 10 4 photon pairs. This implies that, in principle, one might be able to detect two-photon absorption signals up to four orders of magnitude larger than previously reported, thus paving the way towards the first experimental realization of the virtual-state spectroscopy technique.

Entangled photon assisted multidimensional nonlinear optics of exciton–polaritons

“…In this communication, we focus on the transmitted mode pump-probe analog while treating their respective frequencies as the parametric scanning variables for the generation of the spectra. [19][20][21][22][23] In a distinct but concurrent development within the field of the cavity, quantum electrodynamics have shown the ability of the spatially confined photonic modes to interact with the localized matter transitions and modify the dynamical energy landscape. Collective multi-exciton processes, e.g., exciton-migrations, longrange cavity mediated exciton transfer, proximity induced excitonexciton scattering occurring in the interacting exciton harvesting chromophores, namely, quantum aggregates, offer several dynamical features that could change drastically in the presence of the cavity mode.…”

Intense spectrally broad-band twin beams from poled nonlinear crystals

“…These intense twin beams may find their application in metrology as they are more resistant against the noise compared to their low intensity counterparts containing just one photon pair. They have been recently discussed as promising sources for the so-called virtual-state spectroscopy 39 where they allow to increase the absolute two-photon absorption probabilities, that lie in the heart of the method, by four orders in magnitude 40 .…”

Temperature-Controlled Entangled-Photon Absorption Spectroscopy

“…Among different quantum-enabled techniques, entangled-photon virtual-state spectroscopy [20][21][22][23][24][25][26][27][28][29][30][31][32][33] is a promising tool for extracting information about the intermediate, energy non-conserving electronic transitions [34,35], that contribute to the two-photon excitation of a chemical or biological sample. In this technique, virtual-state transitions, a signature of the absorbing medium, are experimentally revealed by introducing a time delay between frequency-correlated photons and averaging over many experimental realizations with differing two-photon state characteristics [20].…”

“…This configuration results in frequency anticorrelation of the down-converted photons and provides the strongest TPA signal (see supplementary materials and Refs. [23,31,32]). The wavelengths of the photons can be tuned around the degenerate wavelength (800 nm) by controlling the crystal temperature T [37].…”

“…Finally, it is important to remark that in order to efficiently identify electronic levels of arbitrary samples, one needs to guarantee that the spectrum of the single photons employed is broad enough so that it overlaps with the electronic levels to be resolved. In cases where the overlap is small, one might need to consider alternative approaches, such as the use of intense entangled beam sources [31,32].…”