arXiv subjects

Mohamad Toutounji

Publications and source records attributed to Mohamad Toutounji.

3 recordsLinked to original sources

arXiv2026

Non-Markovain Quantum State Diffusion for the Tunneling in SARS-COVID-19 virus

In the context of biology, unlike the comprehensively established Standard Model in physics, many biological processes lack a complete theoretical framework and are often described phenomenologically. A pertinent example is olfaction -- the process through which humans and animals distinguish various odors. The conventional biological explanation for olfaction relies on the lock and key model, which, while useful, does not fully account for all observed phenomena. As an alternative or complement to this model, vibration-assisted electron tunneling has been proposed. Drawing inspiration from the vibration-assisted electron tunneling model for olfaction, we have developed a theoretical model for electron tunneling in SARS-CoV-2 virus infection within a non-Markovian framework. We approach this by solving the non-Markovian quantum stochastic Schrodinger equation. In our model, the spike protein and the GPCR receptor are conceptualized as a dimer, utilizing the spin-Boson model to facilitate the description of electron tunneling. Our analysis demonstrates that electron tunneling in this context exhibits inherently non-Markovian characteristics, extending into the intermediate and strong coupling regimes between the dimer components. This behavior stands in stark contrast to predictions from Markovian models, which fail to accurately describe electron tunneling in the strong coupling limit. Notably, Markovian approximations often lead to unphysical negative probabilities in this regime, underscoring their limitations and highlighting the necessity of incorporating non-Markovian dynamics for a more realistic description of biological quantum processes. This approach not only broadens our understanding of viral infection mechanisms but also enhances the biological accuracy and relevance of our theoretical framework in describing complex biological interactions.

q-bio.BM↗

arXiv2026

Non-Markovian and non-Condon vibrationally assisted electron transfer in an effective ligand--receptor complex

We investigate vibrationally assisted electron transfer in an effective ligand--receptor complex using finite-temperature non-Markovian quantum-state diffusion with explicitly colored environmental noise. The model comprises donor and acceptor electronic states, an explicit bound-ligand vibrational mode, and a Gaussian protein--solvent bath. Linearization of a coordinate-dependent diabatic Hamiltonian yields two distinct system--environment interactions: diagonal coupling, which modulates the donor--acceptor energy gap, and off-diagonal non-Condon coupling, which modulates the electronic tunneling matrix element. In the rapidly equilibrating diagonal-bath limit, the model recovers the expected Marcus--Levich--Jortner vibronic-transfer behavior. Persistent environmental correlations instead generate non-exponential dynamics characterized by transient oscillations, back-transfer, and memory-dependent damping. Under matched weak-tunneling conditions, off-diagonal coupling opens a direct transition pathway and produces a larger finite-time acceptor population throughout the investigated parameter space. Because these dynamics do not generally support a unique kinetic rate, the enhancement is quantified using a time-averaged transfer yield. Comparisons with exact closed-system and commuting pure-dephasing limits validate the deterministic propagator and colored-noise construction, respectively, while the noncommuting dynamics are evaluated within a declared first-order finite-memory closure. These results identify ligand vibration, environmental memory, and non-Condon tunneling modulation as cooperating mechanisms that can dynamically regulate electron transfer in receptor-like environments, while maintaining a clear distinction between a mechanistic coarse-grained model and an atomistically parameterized biological complex.

quant-ph↗

arXiv2025

Strong field physics in open quantum systems

Dephasing is the loss of phase coherence due to the interaction of an electron with the environment. The most common approach to model dephasing in light-matter interaction is the relaxation time approximation. Surprisingly, its use in intense laser physics results in a pronounced failure, because ionization {is highly overestimated.} Here, this shortcoming is corrected by developing a strong field model in which the many-body environment is represented by a heat bath. Our model reveals that ionization enhancement and suppression by several orders of magnitude are still possible, however only in more extreme parameter regimes. Our approach allows the integration of many-body physics into intense laser dynamics with minimal computational and mathematical complexity, thus facilitating the identification of novel effects in strong-field physics and attosecond {science}.

physics.optics↗