arXiv subjects

Zahra Sartipi

Publications and source records attributed to Zahra Sartipi.

5 recordsLinked to original sources

arXiv2026

Canonically consistent quantum master equation for proton-transfer reactions

The canonically consistent quantum master equation (CCQME) method to treat system-bath dynamics is used to describe intramolecular proton transfer in the thioacetylacetone molecule (TAA, C5H8OS), modeled as an N-level quantum system coupled to a solvent. The solvent is represented as a harmonic bath (a continuum of oscillators) characterized by an Ohmic-Drude spectral density. We benchmark the secularized population dynamics and steady-state populations predicted by CCQME against numerically exact hierarchical equations of motion (HEOM) theory and compare it to the corresponding secularized Redfield results. Our results reveal that Redfield dynamics deviates increasingly from the HEOM reference as the system-bath coupling strength grows. In contrast, for not-too-strong couplings, the secularized CCQME population dynamics remains consistent with HEOM over an extended system-bath coupling range, and approaches the second-order mean-force Gibbs state. A complementary non-secular calculation shows that retaining population-coherence coupling reveals limitations of the second-order treatment for coherence-sensitive observables.

quant-ph↗

arXiv2023

Optimal performance of voltage-probe quantum heat engines

The thermoelectric performance at a given output power of a voltage-probe heat engine, exposed to an external magnetic field, is investigated in linear irreversible thermodynamics. For the model, asymmetric parameter, general figures of merit and efficiency at a given output power are analytically derived. Results show a trade-off between efficiency and output power, and we recognize optimum-efficiency values at a given output power are enhanced compared to a Büttiker-probe heat engine due to the presence of a characteristic parameter, namely $d_m$. Moreover, similar to a Büttiker-probe heat engine, the universal bounds on the efficiency are obtained, and the efficiency at a given output power can exceed the Curzon-Ahlborn limit. These findings have practical implications for the optimization of realistic heat engines and refrigerators. By controlling the values of the asymmetric parameter, the figures of merit, and $d_m$, it may be possible to design more efficient and powerful thermoelectric devices.

quant-ph↗

arXiv2018

Enhancing Thermoelectric Properties Through a Three-Terminal Benzene Molecule

The thermoelectric transport through a benzene molecule with three metallic terminals is discussed. Using general local and non-local transport coeffcients, we investigated different conductance and thermopower coefficients within the linear response regime. Based on the Onsager coefficient which depend on the number of terminal efficiencies, efficiency at maximum power is also studied. In the three-terminal set up with tuning temperature differences, a great enhancement of the figure of merit is observed. Results also show that the third terminal model can be useful to improve the efficiency at maximum output power compared to the two-terminal model.

cond-mat.mes-hall↗

arXiv2016

Shot Noise of Charge and Spin Current of a Quantum Dot Coupled to Semiconductor Electrodes

Based on the scattering matrix theory and non-equilibrium green function method, we have investigated the fluctuations of charge and spin current of the systems which consists of a quantum dot (QD) with a resonant level coupled to two semiconductor contacts within in alternative site $(AS)$ and alternative bond $(AB)$ framework, where two transverse $(B_x)$ and longitudinal $(B_z)$ magnetic fields are applied to the QD. It is only necessary to use the auto-correlation function to characterize the fluctuations of charge current for a two-terminal system because of the relation which is defined as $\sum_α^e S_{αβ}$ = $\sum_β^e S_{αβ}=0$. Our result shows that both auto-shot noise $(S_{LL})$ and cross-shot noise $(S_{LR})$ are essential to characterize the fluctuations of spin current when $B_x$ is present. Moreover, our model calculations show that the sign of the cross-shot noise of spin current is negative for all surface states of AS/QD/AS junctions, while it oscillates between positive and negative values for two surface states of AB/QD/AB junctions as we sweep the gate voltage.

cond-mat.mes-hall↗

arXiv2015

Effects of quantum interference on the electron transport in the semiconductor$/$benzene$/$semiconductor junction

Using the tight-binding model and the generalized Green's function formalism, the effect of quantum interference on the electron transport through the benzene molecule in a semiconductor/benzene/semiconductor junction is numerically investigated. We show how the quantum interference sources, different contact positions and local gate, can control the transmission characteristics of the electrode/molecule/electrode junction. We also study the occurrence of anti-resonant states in the transmission probability function using a simple graphical scheme (introduced in Ref.[Phys. Chem. Chem. Phys, 2011, 13, 1431]) for different geometries of the contacts between the benzene molecule and semiconductor(silicon and titanium dioxide) electrodes.

cond-mat.mes-hall↗