arXiv subjects

Arunangshu Debnath

Publications and source records attributed to Arunangshu Debnath.

5 recordsLinked to original sources

arXiv2026

Entangled photon pair excitation and time-frequency-filtered multidimensional photon correlation spectroscopy as a probe for dissipative exciton kinetics

In quantum aggregates, delocalized exciton states across energy manifolds interact with phonon modes, making state-resolved spectroscopic monitoring of dynamics challenging. We propose a scheme that combines photon-entanglement-enhanced narrowband excitation of two-exciton states with time-frequency-filtered two-photon coincidence counting, which allows high-resolution probing of dissipative two-exciton dynamics spread across multiple spectral and temporal windows. We demonstrate that entangled photon pairs can be used to prepare narrowband two-exciton population distributions, circumventing transport in the mediating one-exciton manifold, and the redistributed two-exciton population can be monitored using time-frequency-filtered two-photon coincidence counting. Numerical simulations for a light-harvesting aggregate highlight the ability of this protocol to suppress or amplify specific pathways under a realistic scenario. Combining entangled photonic sources with multidimensional photon correlation techniques enable promising applications in spectroscopy and sensing.

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arXiv2026

Coherent nonlinear optical probe for cavity-dressed vibrational mode mixing: Multidimensional double-quantum coherence and photon-echo spectroscopy

Cavity dressing of molecular vibrational dynamics expands the role of characteristic vibrations as spectroscopic markers of underlying ultrafast dynamics. Interacting vibrational modes exhibit a pronounced excited state delocalization due to the interaction with the cavity mode, which is reflected in the ultrafast dynamics. We characterize the ultrafast dynamics of these cavity-dressed characteristic vibrations in the presence of dissipation. Specifically, we present two complementary three-pulse coherent multidimensional spectroscopic techniques capable of monitoring one- and two-quantum cavity-dressed vibrational excitations. Dissipative properties, such as transport and dephasing, are described using a microscopic theory that includes low- and high-energy phonon modes. Simulations were performed with finite laser pulses. The cavity coupling strengths fall within a range similar to vibrational mode couplings, hinting towards a possibility of control of intermolecular vibrational energy redistribution. The framework is extendable to a broad range of cavity-controlled nonlinear spectroscopies of dissipative molecular systems.

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arXiv2026

Photon entanglement-enhanced multidimensional spectroscopy of exciton correlations in photosynthetic aggregates

Nonlinear spectroscopic techniques using entangled photon pairs can provide an opportunity to exploit non-classical correlations encoded in two-photon wavefunctions to manipulate two-exciton wavefunctions. We propose an entangled photon pair-enhanced multidimensional spectroscopic technique that is sensitive to exciton-exciton interactions and correlations at the femtosecond timescale. Simulations for a dissipative system, namely, the photosynthetic aggregate reveal the superior ability of entangled photon pairs, compared to both transform-limited and frequency-chirped laser pulses, to manipulate excited-state absorption pathways. The corresponding spectral features in the two-dimensional spectrogram are interpreted in terms of one- and two-exciton resonances. The signal scales linearly with the incoming intensity of the photon sources. We show that classifying these resonances using entangled photon source in the perturbative limit allow for probing exciton correlations at the natural energy scale. These insights can be used to explore multi-exciton dynamics in molecular systems using multiphoton entanglement.

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arXiv2023

Theory of high-energy correlated multiphoton x-ray diffraction for synchrotron radiation sources

We present a theoretical formulation for the multiphoton diffraction phenomenology in the nonrelativistic limit, suitable for interpreting high-energy x-ray diffraction measurements using synchrotron radiation sources. A hierarchy of approximations and the systematic analysis of limiting cases are presented. A convolutional representation of the diffraction signal allows classification of the physical resources contributing to the correlation signatures. The formulation is intended for developing a theoretical description capable of describing plausible absence or presence of correlation signatures in elastic and inelastic diffractive scattering. Interpreting these correlation signatures in terms of the incoming field modulated many-body electronic density correlations provides a novel perspective for structural imaging studies. More essentially, it offers a framework necessary for theoretical developments of associated reconstruction algorithms.

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arXiv2022

Entangled biphoton enhanced double quantum coherence signal as a probe for cavity polariton correlations in presence of phonon induced dephasing

We theoretically propose a biphoton entanglement-enhanced multidimensional spectroscopic technique as a probe for the dissipative polariton dynamics in the ultrafast regime. It is applied to the cavity-confined monomeric photosynthetic complex that represents a prototypical multi-site excitonic quantum aggregate. The proposed technique is shown to be particularly sensitive to inter-manifold polariton coherence between the two and one-excitation subspaces. It is demonstrated to be able to monitor the dynamical role of cavity-mediated excitonic correlations, and dephasing in the presence of phonon-induced dissipation. The non-classicality of the entangled biphoton sources is shown to enhance the ultra-fast and broadband correlation features of the signal, giving an indication about the underlying state correlations responsible for long-range cavity-assisted exciton migration.

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