Fundamental aspects of steady-state conversion of heat to work at the nanoscale

?? ????? ??????? ??? ????????????? ?????? ??????? ???? ??????? ????????????? ??? ???????? ?? 1978 ??? ?? ????? ?????? ???? ??? ?? 1980. ??????, ??????????? ??? 2020, ??????? 17 ???? ??? ??? ??????? 25 ?????????. ?? 1995 ?? ????? ??????????? ??? ????????? ?????? ???? ??????? ??? ??????, ???? ????????????????? ??? ???????? ??? ?????? ??? ????????? ?????? 8 ??? ??????????? ??? ??? ???? ??? ?????????. ?? ???????? ??? ????? ?????? ??? ????? ????????? ?? ????? ??????? ???? ?? ?? ????? ????????? ??????????? [1] ??? ?? ?????? ??????????? ???? ???????? [2], ???????? ??? Univ. of Southern California (???).

/pdf/seoul-sojae-7gae-jonghabbyeongweon-amhwanjadeulyi-2y5bbrkske.pdf

서울 소재 7개 종합병원 암환자들의 보완대체요법 이용양상

Abstract Memristors are one of the emerging technologies that can potentially replace state-of-the-art integrated electronic devices for advanced computing and digital and analog circuit applications including neuromorphic networks. Over the past few years, research and development mostly focused on revolutionizing the metal oxide materials, which are used as core components of the popular metal-insulator-metal memristors owing to their highly recognized resistive switching behavior. This paper outlines the recent advancements and characteristics of such memristive devices, with a special focus on (i) their established resistive switching mechanisms and (ii) the key challenges associated with their fabrication processes including the impeding criteria of material adaptation for the electrode, capping, and insulator component layers. Potential applications and an outlook into future development of metal oxide memristive devices are also outlined.

/pdf/state-of-the-art-of-metal-oxide-memristor-devices-2zohemrfvm.pdf

State of the art of metal oxide memristor devices

Thermodynamic uncertainty relations (TURs) place strict bounds on the fluctuations of thermodynamic quantities in terms of the associated entropy production. In this Letter, we identify the tightest (and saturable) matrix-valued TUR that can be derived from the exchange fluctuation theorems describing the statistics of heat and particle flow between multiple systems of arbitrary dimensions. Our result holds for both quantum and classical systems, undergoing general finite-time nonstationary processes. Moreover, it provides bounds not only for the variances, but also for the correlations between thermodynamic quantities. To demonstrate the relevance of TURs to the design of nanoscale machines, we consider the operation of a 2-qubit swap engine undergoing an Otto cycle and show how our results can be used to place strict bounds on the correlations between heat and work.

Thermodynamic Uncertainty Relations from Exchange Fluctuation Theorems

Various engine types are thermodynamically equivalent in the quantum limit of small “engine action”. Our previous derivation of the equivalence is restricted to Markovian heat baths and to implicit classical work repository (e.g., laser light in the semi-classical approximation). In this paper, all the components, baths, batteries, and engines, are explicitly taken into account. To neatly treat non-Markovian dynamics, we use mediating particles that function as a heat exchanger. We find that, on top of the previously observed equivalence, there is a higher degree of equivalence that cannot be achieved in the Markovian regime. Next, we focus on the quality of the battery charging process. A condition for positive energy increase and zero entropy increase (work) is given. Moreover, it is shown that, in the strong coupling regime, it is possible to super-charge a battery. With super-charging, the energy of the battery is increased while its entropy is being reduced at the same time.

Quantum Heat Machines Equivalence, Work Extraction beyond Markovianity, and Strong Coupling via Heat Exchangers

In a step toward the conversion of excess heat into electric current, researchers demonstrate a device that generates current in response to voltage fluctuations that mimic heat.

/pdf/voltage-fluctuation-to-current-converter-with-coulomb-2q2nvkeis4.pdf

Voltage fluctuation to current converter with Coulomb-coupled quantum dots.

Although noise is usually undesirable, by means of stochastic resonance it can actually be exploited, for example to improve the performance and switch the functionality of nanoelectronic systems. The authors demonstrate a device that rectifies voltage fluctuations and changes its behavior controllably to act as any of four logic gates. These findings lay the physical groundwork for energy-efficient, noise-tolerant, and autonomous electronics, and the particular device is based on the mature GaAs/(Al,Ga)As system, suggesting straightforward integration with existing technology.

/pdf/logical-stochastic-resonance-with-a-coulomb-coupled-quantum-5ez6jujtlc.pdf

Logical stochastic resonance with a coulomb-coupled quantum dot rectifier

We report on the observation of photogalvanic effects induced by terahertz radiation in type-II GaSb/InAs quantum wells with inverted band order. Photocurrents are excited at oblique incidence of radiation and consist of several contributions varying differently with the change of the radiation polarization state; the one driven by the helicity and the other one driven by the linearly polarization of radiation are of comparable magnitudes. Experimental and theoretical analyses reveal that the photocurrent is dominated by the circular and linear photogalvanic effects in a system with a dominant structure inversion asymmetry. A microscopic theory developed in the framework of the Boltzmann equation of motion considers both photogalvanic effects and describes well all the experimental findings.

/pdf/circular-and-linear-photogalvanic-effects-in-type-ii-gasb-41lecejl9q.pdf

Circular and linear photogalvanic effects in type-II GaSb/InAs quantum well structures in the inverted regime

We study the optical tunability of the charge carrier type in InAs/GaSb double quantum wells with its type-II broken band alignment and inverted band structure. Under constant optical excitation, the majority charge carrier type switches from electron to hole. Within the majority charge carrier type transition, the coexisting minority charge carrier contribution indicates electron-hole hybridization with a nontrivial topological insulating phase. The optical tuning is attributed to the negative photoconductivity of antimonide materials in combination with a persistent charge carrier buildup of photogenerated charges at the surface and substrate side of the device, respectively. Our study of the tuning of an InAs/GaSb double quantum well heterostructure reveals that an electro-optical switching is possible and paves the way to an optical control of the phase diagram of InAs/GaSb topological insulators.

/pdf/optical-tuning-of-the-charge-carrier-type-in-the-topological-4he6pa2hvl.pdf

Optical tuning of the charge carrier type in the topological regime of InAs/GaSb quantum wells

In this paper we demonstrate two realizations of a half adder based on a voltage-rectifying mechanism involving two Coulomb-coupled quantum dots. First, we examine the ranges of operation of the half adder's individual elements, the AND and XOR gates, for a single rectifying device. It allows a switching between the two gates by a control voltage and thus enables a clocked half adder operation. The logic gates are shown to be reliably operative in a broad noise amplitude range with negligible error probabilities. Subsequently, we study the implementation of the half adder in a combined double-device consisting of two individually tunable rectifiers. We show that this double device allows a simultaneous operation of both relevant gates at once. The presented devices draw their power solely from electronic fluctuations and are therefore an advancement in the field of energy efficient and autonomous electronics.

/pdf/half-adder-capabilities-of-a-coupled-quantum-dot-device-3fpvgpac53.pdf

P. Pfeffer

Papers

Voltage fluctuation to current converter with Coulomb-coupled quantum dots.

Logical stochastic resonance with a coulomb-coupled quantum dot rectifier

Circular and linear photogalvanic effects in type-II GaSb/InAs quantum well structures in the inverted regime

Optical tuning of the charge carrier type in the topological regime of InAs/GaSb quantum wells

Half adder capabilities of a coupled quantum dot device