Power, Efficiency and Fluctuations in a Quantum Point Contact as Steady-State Thermoelectric Heat Engine

Kheradsoud, Sara; Dashti, Nastaran; Misiorny, Maciej; Potts, Patrick P.; Splettstoesser, Janine; Samuelsson, Peter

doi:10.3390/e21080777

Cited by 45 publications

(25 citation statements)

References 56 publications

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“…Therefore, the edge states appear in helical Kramer's pairs [32][33][34][35][36][37] with opposite spin orientations determined by the spin orbit of the TI. Several heat engines and refrigerators have been recently proposed, taking advantage of the fundamental chiral nature of the quantum Hall edge states, which manifests itself in multiple-terminal structures [19] and in quantum interference [20,21]. Recently, the property of charge fractionalization was also pointed out as a mechanism to enhance thermoelectricity [23].…”

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confidence: 99%

Optimal Thermoelectricity with Quantum Spin Hall Edge States

2019

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We study the thermoelectric properties of a Kramer's pair of helical edge states of the quantum spin Hall effect coupled to a nanomagnet with a component of the magnetization perpendicular to the direction of the spin-orbit interaction of the host. We show that the transmission function of this structure has the desired qualities for optimal thermoelectric performance in the quantum coherent regime. For a single magnetic domain there is a power generation close to the optimal bound. In a configuration with two magnetic domains with different orientations, pronounced peaks in the transmission functions and resonances lead to a high figure of merit. We provide estimates for the fabrication of this device with HgTe quantum-well topological insulators. Introduction.Thermoelectricity in the quantum regime is attracting high interest for some years now [1,2]. Systems hosting edge states, like the quantum Hall and quantum spin Hall are paradigmatic realizations of quantum coherent transport. Several theoretical and experimental results on heat transport and thermoelectricity in these systems have been recently reported .Unlike the quantum Hall state, which is generated by a strong magnetic field, the quantum spin Hall (QSH) state taking place in two-dimensional (2D) topological insulators (TI), preserves time-reversal invariance. Therefore, the edge states appear in helical Kramer's pairs [32][33][34][35][36][37] with opposite spin orientations determined by the spin orbit of the TI. Several heat engines and refrigerators have been recently proposed, taking advantage of the fundamental chiral nature of the quantum Hall edge states, which manifests itself in multiple-terminal structures [19] and in quantum interference [20,21]. Recently, the property of charge fractionalization was also pointed out as a mechanism to enhance thermoelectricity [23]. All these setups rely on the existence of quantum point contacts and quantum dots in the structure, tunnel-coupled to the edge states, which are generated by recourse to constrictions. The fabrication of these elements is nowadays normal in the context of the quantum Hall effect [38][39][40]. However, their realization in the context of the QSH effect remains an experimental challenge so far [41], although they are widely investigated theoretically [42][43][44][45][46][47][48][49][50][51].In the quantum coherent regime the electronic transport properties take place without inelastic scattering and are fully characterized by a transmission function. Particle-hole symmetry breaking is a necessary condition for steady-state heat to work conversion. Having transmission functions rapidly changing in energy within the relevant transport window, is the key to achieve optimal thermoelectricity [2,[52][53][54][55]. The optimal performance is usually quantified by the figure of merit ZT , with the Carnot limit achieved for ZT → ∞. This ideal limit can be realized for transmission functions containing deltafunction like peaks [52]. In this sense, structures with resonant levels like quant...

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confidence: 99%

Optimal Thermoelectricity with Quantum Spin Hall Edge States

2019

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“…Since we aim to show the principles of the operation in this section, we focus on one simple realization of the fourterminal setup, where both the scatterers in the resource region and the working substance are given by QPCs with sharp steplike transmission probabilities, see Eq. 5, as these are expected to give good energy resolution and at the same time to provide large currents [100]. Analytical expressions for this choice of transmission probabilities are given in Appendix A.…”

Section: Demonic Action Of a Nonequilibrium Resourcementioning

confidence: 99%

Quantifying nonequilibrium thermodynamic operations in a multiterminal mesoscopic system

Hajiloo¹,

Sánchez²,

Whitney³

et al. 2020

Phys. Rev. B

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We investigate a multiterminal mesoscopic conductor in the quantum Hall regime, subject to temperature and voltage biases. The device can be considered as a nonequilibrium resource acting on a working substance. We previously showed that cooling and power production can occur in the absence of energy and particle currents from a nonequilibrium resource (calling this an N-demon). Here we allow energy or particle currents from the nonequilibrium resource and find that the device seemingly operates at a better efficiency than a Carnot engine. To overcome this problem, we define free-energy efficiencies which incorporate the fact that a nonequilibrium resource is consumed in addition to heat or power. These efficiencies are well behaved for equilibrium and nonequilibrium resources and have an upper bound imposed by the laws of thermodynamics. We optimize power production and cooling in experimentally relevant parameter regimes.

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“…Despite the advances in optimization, there is a specific unsolved issue: the systematic treatment of the influence of lack of control 37 . There are open questions regarding the role of constancy (fluctuations in the energetic output records) 38 – 40 , which could be ultimately related to power fluctuations with large efficiencies 38 , 39 or the enhancement of energy converters performance due to fluctuations from small scale and quantum nature as recently proposed 41 – 43 . Major differences have been recently reported for quasistatic and steady state HE models operating close to the reversible efficiency 39 .…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic optimization subsumed in stability phenomena

González-Ayala

Medina

Roco

et al. 2020

Sci Rep

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in the present paper the possibility of an energetic self-optimization as a consequence of thermodynamic stability is addressed. this feature is analyzed in a low dissipation refrigerator working in an optimized trade-off regime (the so-called Omega function). The relaxation after a perturbation around the stable point indicates that stability is linked to trajectories in which the thermodynamic performance is improved. furthermore, a limited control over the system is analyzed through consecutive external random perturbations. The statistics over many cycles corroborates the preference for a better thermodynamic performance. endoreversible and irreversible behaviors play a relevant role in the relaxation trajectories (as well as in the statistical performance of many cycles experiencing random perturbations). A multi-objective optimization reveals that the well-known endoreversible limit works as an attractor of the system evolution coinciding with the pareto front, which represents the best energetic compromise among efficiency, entropy generation, cooling power, input power and the omega function. Meanwhile, near the stable state, performance and stability are dominated by an irreversible behavior.

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Power, Efficiency and Fluctuations in a Quantum Point Contact as Steady-State Thermoelectric Heat Engine

Cited by 45 publications

References 56 publications

Optimal Thermoelectricity with Quantum Spin Hall Edge States

Optimal Thermoelectricity with Quantum Spin Hall Edge States

Quantifying nonequilibrium thermodynamic operations in a multiterminal mesoscopic system

Thermodynamic optimization subsumed in stability phenomena

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