arXiv subjects

Jayasmita Behera

Publications and source records attributed to Jayasmita Behera.

4 recordsLinked to original sources

arXiv2024

Thermoelectric performance of a minimally nonlinear voltage probe and voltage-temperature probe heat engine with broken time-reversal symmetry

We investigate the thermoelectric performance of minimally nonlinear irreversible heat engines with broken time-reversal symmetry (TRS), realized through voltage and voltage-temperature probe configurations. Our framework extends the Onsager relations by incorporating a nonlinear power dissipation term into the heat current. We derive and analyze analytical expressions for the efficiency at a given power and the efficiency at maximum power (EMP), expressed in terms of asymmetry parameters and generalized figures of merit. Our analysis reveals that the combined effects of broken TRS and nonlinear dissipation give rise to two universal bounds on the EMP that can surpass the Curzon-Ahlborn (CA) limit. Although these bounds share a similar analytical form, differences in Carnot efficiency and asymmetry parameters lead to distinct operational characteristics, as shown through numerical simulations. We consider a triple-quantum-dot Aharonov-Bohm heat engine incorporating either a voltage probe or a voltage-temperature probe. In both cases, TRS is broken by the magnetic flux. However, the voltage-temperature probe requires an additional anisotropy in the system for its TRS-breaking effects to significantly influence transport. We examine the role of this anisotropy in enhancing performance. Our results show that the EMP and efficiency at a given power can be enhanced by increasing the strength of nonlinear power dissipation, even though the output power remains unchanged. The voltage probe configuration generally yields higher power, while the voltage-temperature probe is more efficient, except in certain regimes where large asymmetries and high figures of merit allow the voltage probe setup to outperform.

cond-mat.mes-hall↗

arXiv2024

A review on Aharonov-Bohm quantum machines: Thermoelectric heat engines and diodes

The study of heat-to-work conversion has gained significant attention in recent years, highlighting the potential of nanoscale systems to achieve energy conversion in steady-state devices without any macroscopic moving parts. This review examines the theoretical frameworks governing the steady-state flows of quantum particles like electrons, photons, and phonons within various mesoscopic or nanoscale devices, such as thermoelectric heat engines in the context of quantum dot Aharonov-Bohm (AB) interferometric configurations. Quantum interference effects hold great promise for enhancing the thermoelectric transport properties of such quantum devices by allowing more precise control over energy levels and transport pathways. Driven quantum dot AB networks can maintain quantum coherence and provide precise experimental control. Unlike bulk systems, nanoscale systems like quantum dots reveal distinct quantum interference phenomena, including sharp features in transmission spectra and Fano resonances. This review highlights the distinction between optimization methods that produce boxcar functions and coherent control methods that result in complex interference patterns. It reveals that the effective design of thermoelectric heat engines requires careful tailoring of quantum interference and the magnetic field-induced effects to enhance performance. We emphasize how magnetic fields can change the bounds of power or efficiency. These machines with broken time-reversal symmetry provide insights into directional dependencies and asymmetries in quantum transport. We offer a thorough overview of past and current research on quantum thermoelectric heat engines using the AB effect and present a detailed review of three-terminal AB heat engines, where broken time-reversal symmetry can induce a coherent diode effect. We cover bounds on power and efficiency in systems with broken time-reversal symmetry.

cond-mat.mes-hall↗

arXiv2023

Quantum coherent control of nonlinear thermoelectric transport in a triple-dot Aharonov-Bohm heat engine

We investigate the role of quantum coherence and higher harmonics resulting from multiple-path interference in nonlinear thermoelectricity in a two-terminal triangular triple-dot Aharonov-Bohm (AB) interferometer. We quantify the trade-off between efficiency and power in the nonlinear regime of our simple setup comprising three non-interacting quantum dots (two connected to two biased metallic reservoirs) placed at the vertex of an equilateral triangle, and a magnetic flux $\Phi$ pierces it perpendicularly. For a spatially symmetric setup, we achieve optimal efficiency and power output when the inter-dot tunneling strength is comparable to the dot-lead coupling, AB phase $\phi=\pi/2$. Our analysis reveals that the presence of higher harmonics is necessary but not sufficient to achieve optimal power output. The maximal constructive interference represented by three close-packed resonance peaks of the unit transmission can enhance the power output ($P_{max}\sim 2.35\,\mathrm{fW}$) almost 3.5 times as compared to the case where only a single channel participates in the transport, and the corresponding efficiency is about $0.80\eta_{c}$ where $\eta_{c}$ is the Carnot efficiency. Geometric asymmetries and their effects on efficiency and power output are also investigated. An asymmetric setup characterized by the ratio of the coupling to the source and the drain terminals ($x$) can further enhance the maximum power output $P_{max}\sim 3.85\,\mathrm{fW}$ for $x=1.5$ with the same efficiency as that of the symmetric case. Our investigation reveals that the output power and efficiency are optimal in the wide-band limit. The power output is significantly reduced for the narrow-band case. On the other hand, disorder effects radically reduce the performance of the heat engine.

cond-mat.mes-hall↗

arXiv2021

Environment dependent vibrational heat transport in molecular Junctions : Rectification, quantum effects, vibrational mismatch

Vibrational heat transport in molecular junctions is a central issue in different contemporary research areas like Chemistry, material science, mechanical engineering, thermoelectrics and power generation. Our model system consists of a chain of molecules which sandwiched between two solids that are maintained at different temperatures. We employ quantum self-consistent reservoir model, which is built on generalized quantum Langevin equation, to investigate quantum effects and far from equilibrium conditions on thermal conduction at nanoscale. The present self-consistent reservoir model can easily mimic the phonon-phonon scattering mechanisms. Different thermal environments are modelled as (i) Ohmic, (ii) sub-Ohmic, and (iii) super-Ohmic environment and their effects are demonstrated for the thermal rectification properties of the system with spring graded or mass graded feature. The behavior of heat current across molecular junctions as a function of chain length, temperature gradient and phonon scattering rate are studied. Further, our analysis reveals the effects of vibrational mismatch between the solids phonon spectra on heat transfer characteristics in molecular junctions for different thermal environments.

cond-mat.stat-mech↗