arXiv subjects

Trishna Kalita

Publications and source records attributed to Trishna Kalita.

5 recordsLinked to original sources

arXiv2026

Coherence Estimation Beyond the Liouvillian Gap in a Finite Nonequilibrium System

We investigate the estimation of bath-induced coherence in a finite quantum system interacting with thermal reservoirs. Enhancement of coherence estimation is transient and the estimation precision totally disappears at the steady state despite the system retaining finite coherence. By analyzing the full Liouvillian eigenspectrum, we demonstrate that the optimal sensing window emerges from the competition between identifiable contributory modes' temporal relaxation and statistical importance. Neither is the linear inverse scaling of Liouvillian gap with transient optimal time a signature of unimodal contribution to optimal sensing, nor is the existence of multimodal dynamics a signature of nonlinear scaling. The inverse Liouvillian gap does not obey any general scaling with the optimal sensing time of coherence and we prove our numerical results analytically using a general Markovian framework. We further show that coupling the finite system to a quantum cavity and maintaining a thermal bias, transforms the transient metrological optimization into a sustained steady-state resource.

quant-ph↗

arXiv2026

Thermodynamics of a biophotomimetic nonreciprocal quantum battery

We propose a theoretical model of a fully functional nonreciprocal quantum battery inspired by the architecture of bacterial light-harvesting complexes. We assign functional roles to collective quantum optical subradiant and superradiant states and introduce a unimodal cavity to assist storage. The transition rates are obtained from an effective non-Hermitian Hamiltonian, tailored to the battery geometry which are fed into a master equation to unravel the time evolution. We investigate the complete thermodynamic performance including storage, leakage, ergotropy, work extraction, flux, and power. We observe optimization at different ring sizes, each peaking at its specific energetic function. Strong coupling between the ring and central system enhances the battery's ability to store energy but reduces the ability of power output. The ergotropy exceeds capacity and approaches it linearly with increasing system size, with an optimal small-size regime that disappears under strong coupling.

quant-ph↗

arXiv2025

Coherence in the Leak and Storage Kurtosis control Ergotropy in Quantum Batteries

We introduce a cavity-coupled finite quantum system which can act as a quantum battery by harnessing noise induced coherences. We apply the methodology of full counting statistics to capture higher-order fluctuations of quanta exchange in the storage station. Together with the thermodynamic parameters, the fluctuations constitute a training platform for unsupervised as well as supervised learning models in predicting ergotropy. We identify a minimal predictive feature set from the battery's operating parameters that can classify the ergotropy into different regimes with great accuracy.Our results show that the usual quantum and thermodynamic variables are inadequate for the purpose of identifying high ergotropy regimes in isolation. Rather, it is the kurtosis of quanta exchange in the storage and the noise-induced coherence in the leakage mode that become the dominant quantities in controlling the magnitude of ergotropy.

quant-ph↗

arXiv2025

Ergotropy of a Photosynthetic Reaction Center

We theoretically analyze the Photosystem II reaction center using a quantum master equation approach, where excitonic and charge-transfer rates are computed at the Redfield and Förster levels with realistic spectral densities. The focus is on ergotropy, the maximum work extractable from a quantum state without energy loss. We compute the ergotropy by constructing passive states in the thermodynamic sense. Among the electron transfer pathways, those involving charge separation between $Chl_{D1}$ and $Phe_{D1}$, as well as a route passing through three sequential charge-separated states, yield higher ergotropy, suggesting greater capacity for work extraction, akin to quantum energy capacitors. A third pathway, bypassing the $Chl_{D1},Phe_{D1}$ pair, shows significantly reduced ergotropy. These differences arise from population-induced transitions between active and passive regimes. Our findings highlight how biological systems may exploit non-equilibrium population structures to optimize energy conversion, connecting quantum thermodynamic principles to biological energy harvesting.

physics.chem-ph↗

arXiv2025

Fischer Information of a Nonequilibrium Anharmonic Donor-Acceptor Rectifier

We investigate a nonequilibrium donor-acceptor quantum rectifier system coupled to an anharmonic vibrational mode, treating the vibrational dynamics both as a two-level system and as multilevel system. The time-dependent Fischer information is then calculated by deriving a quantum master equation for the reduced system dynamics. We estimate some key rectifier parameters, the donor energy, the acceptor energy, and the vibrational frequency. We report that there is an optimal time for estimating the donor and acceptor energy. However, the anharmonic mode can be estimated better only in the steadystate. The acceptor energy is found to be most precisely estimable, especially under strong coupling and high bias. Donor energy shows limited sensitivity, while vibrational frequency estimation benefits from low temperatures. This work offers a theoretical foundation for enhancing parameter estimation in nanoscale quantum devices, guiding future sensing and metrological applications in quantronic systems.

quant-ph↗