Entangled Photon-Pair Two-Dimensional Fluorescence Spectroscopy (EPP-2DFS)

Abstract

We introduce a new method, called entangled photon-pair two-dimensional fluorescence spectroscopy (EPP-2DFS), to sensitively probe the nonlinear electronic response of molecular systems. The method incorporates a separated two-photon ('Franson') interferometer, which generates time-frequency-entangled photon pairs, into the framework of a fluorescence-detected 2D optical spectroscopic experiment. The entangled photons are temporally shaped and phase-modulated in the interferometer, and are used to excite a two-photon-absorbing (TPA) sample, whose excited-state population is selectively detected by simultaneously monitoring the sample fluorescence and the exciting fields. In comparison to 'classical' 2DFS techniques, major advantages of this scheme are the suppression of uncorrelated background signals, the enhancement of simultaneous time-and-frequency resolution, the suppression of diagonal 2D spectral features, and the enhancement and narrowing of off-diagonal spectral cross-peaks that contain information about electronic couplings. These effects are a consequence of the pure-state field properties unique to a parametric down-conversion light source, which must be included in the quantum mechanical description of the composite field-molecule system. We numerically simulate the EPP-2DFS observable for the case of an electronically coupled molecular dimer. The EPP-2DFS spectrum is greatly simplified in comparison to its classical 2D counterpart. Our results indicate that EPP-2DFS can provide previously unattainable resolution to extract model Hamiltonian parameters from electronically coupled molecular dimers.

Nonlinear optical signals and spectroscopy with quantum light

“…Finally it is worth noting an additional advantage of using entangled photons for two-photon excitation in molecules pointed out by (Raymer et al, 2013). In many aggregates, as the doubly-excited state undergoes rapid nonradiative decay to the singly excited states.…”

“…In the context of this article, what they have performed is similar to a four-step phase-cycling scheme, where four sets of data need to be collected and linearly combined. (Raymer et al, 2013) had exploited the formal similarity between the TPIF and a photon coincidence signal to propose the setup shown in Fig. 15a).…”

Efficient photon triplet generation in integrated nanophotonic waveguides

“…(6). Given an optimal device length L opt , we must thus minimize the phase mismatch Δk for the desired combination of pump and signal frequencies.…”

“…Entangled photons have applications in many fields, such as quantum cryptography [2], quantum metrology [3], quantum imaging [4,5], quantum spectroscopy [6], and quantum information processing [7]. Many experimental efforts aim towards the generation, manipulation, and detection of entangled photons using nanoscale optical devices that provide a compact and scalable platform to perform quantum optics experiments on a single chip [1].…”

Matter correlations induced by coupling to quantum light

“…Moreover, the possible exploitation of strong correlations in nonlinear spectroscopy with quantum light promises new routes to probe complex quantum systems [5][6][7][8][9]. Quantum spectroscopy offers increased signal strength at low photon fluxes [10][11][12], new control parameters to disentangle complex spectra [13][14][15][16], the control of exciton distributions [17][18][19][20], and the suppression of exciton transport [21] thanks to the unusual combination of high temporal and spectral resolution. However, whether all of these effects are genuine quantum effects in the sense that they may not be mimicked-at least in principle-by properly shaped pulses with classical correlations [22][23][24] remains an open topic.…”