The efficient manipulation of thermodynamic states within the finite time is fundamentally constrained by the intrinsic dissipative cost. While the slow-driving regime is well-characterized by a universal 1/τ-scaling of irreversibility, the physics governing fast, non-adiabatic transitions remains elusive. Here, we propose the polytropic steering protocols that provide an exact analytical bridge between the isothermal and adiabatic limits for Brownian particles far-from-equilibrium. We demonstrate that for any protocol duration τ, the system can be precisely steered along a prescribed polytropic trajectory, revealing a striking non-monotonic dependence of irreversibility on the driving rate. Contrary to the near-equilibrium paradigm where faster driving necessitates higher energetic costs, we identify a most-irreversible timescale, beyond which dissipation is anomalously suppressed by rapid driving. By mapping these protocols onto a broad class of controllable thermodynamic cycle, we establish power-efficiency tradeoffs and position the polytropic index as a genuine thermodynamic control knob for the rational design of high-speed, high-performance microscopic thermal machines.

We investigate a probe state preparation protocol based on two non-selective generalized quantum measurements to enhance parameter estimation in single-qubit systems. By fine-tuning the measurement strengths, we demonstrate the ability to design a broad class of probe states, initially prepared in a thermal state, which can be optimized for specific estimation tasks. We apply this framework to characterize the decay rate and the temperature of a generalized amplitude damping channel. Our results show that the preparation protocol significantly modulates the quantum Fisher information for both parameters. Furthermore, we derive a general analytical relationship between the quantum Fisher information, thermodynamic susceptibilities, and Hamiltonian variance, valid even in the transient regime. This connection highlights the role of energy fluctuations and kinetic response in determining metrological precision. Finally, we briefly discuss a quantum circuit for experimental implementation using nuclear magnetic resonance techniques.

In open quantum systems with strong symmetries, the global scaled cumulant generating function (SCGF) is generally nonanalytic, so the Gärtner-Ellis theorem cannot directly yield the genuine large-deviation rate function. To address this issue, we propose that the theorem remains valid within blocks of the systems' operator space: we first obtain local rate functions for each block via the theorem and then recover the global one by minimization. This approach is justified by the dissipative freezing phenomenon in such systems. We demonstrate the scheme in an analytical model and a three-spin model with XX interaction. In the latter, we find that the vanishing of a nonanalytic point in the global SCGF under dephasing appears as an avoided ``level'' crossing, and we quantify this behavior using a degenerate perturbation theory.

We derive general trade-off relations between the power, efficiency, and constancy for two-terminal thermoelectric systems in the linear-response regime. Constancy, which quantifies the steadiness of the heat engine, is measured by its fluctuations. The bounds of the efficiency, power, and fluctuations are valid even when time-reversal symmetry is broken, revealing how such a symmetry breaking alters the fundamental constraints on steady-state energy conversion. Our results extend and refine previously established universal trade-offs, offering deeper insight into the performance limits in nonequilibrium thermodynamics. Guided by this bound, heat engines with broken time-reversal symmetry can be operated at near Carnot efficiency while maintaining finite power output and fluctuations, enabling them to outperform their traditional counterparts.

Graphene exhibits great potential in near-field thermal radiation regulation due to its tunable electronic properties and ability to support polariton excitation.In this work,symmetric and asymmetric near-field thermal diode models composed of multilayer graphene-covered silicon carbide(SiC)substrates are constructed,and the synergistic regulation of graphene layer number,chemical potential,and gap distance on the radiative heat flux and rectification ratio is systematically investigated.The results show that the modulation effect of graphene chemical potential and layer number on the heat flux strongly depends on the gap distance.Compared with the structure without graphene coating(SiC-SiC)and the asymmetric graphene-covered structure(GSiC-SiC),the symmetric monolayer and multilayer graphene-covered structures(MGSiC-MGSiC)significantly enhance the radiative heat flux at small gap distances(d＜300 nm),and heat flux presents a peak as the chemical potential rises.In the gap distance range of 50-500 nm,the radiative heat flux increases with the graphene layer number,but the enhancement gradually slows down as the layer number further increases.For asymmetric graphene-covered structures(GSiC-SiC,MGSiC-SiC,MGSiC-GSiC),increasing the chemical potential or the layer number is detrimental to the enhancement of the radiative heat flux at small gap distance(d＜300 nm);at large gap distance(d＞300 nm),the modulation effect of graphene chemical potential and layer number on the heat flux tends to zero.For the asymmetric graphene-covered structure(MGSiC-SiC),reducing the chemical potential(0.5,0.3,0.1 eV)and decreasing the layer number(from 4 to 1)effectively improve the thermal rectification ratio.Numerical calculations show that when the graphene layer number,chemical potential and gap distance are 1,0.1 eV,and 30 nm,respectively,the rectification ratio of the MGSiC-SiC structure reaches 0.155.For the MGSiC-GSiC structure,as the layer number increases from 1 to 4,the maximum rectification ratio of 0.035 is achieved at 3 layers,100 nm and a chemical potential of 0.1 eV.For all asymmetric structures(GSiC-SiC,MGSiC-SiC,MGSiC-GSiC),the maximum rectification ratios appear in the near-field region.These results indicate that a smaller gap distance,lower chemical potential,and fewer graphene layers are favorable for achieving superior thermal rectification performance in asymmetric graphene-covered structures.This study reveals the synergistic regulation mechanism among graphene layer number,chemical potential,and near-field effects,providing theoretical guidance for the design of high-performance near-field thermal rectifiers.

Quantum thermal machines offer promising platforms for exploring the fundamental limits of thermodynamics at the microscopic scale. Building on majorization theory, we further extend the catalytic concept to a two-stroke quantum refrigerator via discrete strokes. The working medium consists of two two-level systems and two heat reservoirs at different temperatures and is assisted by an auxiliary system acting as a catalyst. We show that the presence of the catalyst leads to two significant enhancements: it enables the coefficient of performance and the cooling capacity to exceed the Otto bound and allows the refrigerator to operate in frequency and temperature regimes that are inaccessible without a catalyst. These results highlight the potential of catalytic mechanisms to broaden the operational capabilities of quantum thermal devices and to surpass conventional thermodynamic performance limits.

We investigate the thermodynamic uncertainty relations (TURs) in steady-state transport for a multi-terminal system consisting of two conducting terminals and N-2 probe terminals, within the linear response regime under broken time-reversal symmetry. We independently derive exact bounds on the TURs for the steady-state particle and heat currents under a strong constraint on the Onsager coefficients. Based on our proposed exact bounds, the analysis reveals that the bounds differ for particle and heat currents and are dependent on the system parameters. Furthermore, we demonstrate that under specific parameter conditions, the TURs of the particle and heat currents have a unified minimum value that depends solely on the number of terminals.

As a fundamental measure of stability in nonequilibrium thermodynamics, fluctuations provide critical insight into the performance and reliability of heat engines. In this work, we establish universal fluctuation-dissipation bounds that directly link energy-current fluctuations to both the entropy production rate and steady-state transport currents. Our results are applicable to arbitrary temperature and chemical potential gradients and hold for all steady states within the framework of quantum scattering theory. These bounds remain robust even in regimes where quantum effects break classical thermodynamic uncertainty relations. We demonstrate their validity by using boxcar transmission functions and further derive constraints on the power output from the perspective of fluctuations and dissipation, offering a unified thermodynamic guideline for the design and evaluation of nanoscale and quantum thermal devices.

It is found from textbooks that there are the different versions of the schematic diagram related to the Nernst equation, and consequently, it leads to some discussion related to the Nernst equation and the discovery of other meaningful schematic diagrams never appearing in literature. It is also found that through the introduction of a new function, the schematic diagram of the Nernst equation in the isothermal process of any thermodynamic system can be generated in a unified way and that the Nernst equation can be re-obtained from the experimental data of low-temperature chemical reactions without any artificial additional assumptions. The results obtained here show clearly that the centenary progress from the Nernst theorem to the Nernst statement is completed.

Topological physics has garnered attention across various fields, emphasizing topologically protected modes renowned for their robustness against disorders. Recent advancements have expanded from conservative wave systems to diffusion systems with dissipative interactions. However, the transition region between wave and diffusion dynamics remains scarce, primarily due to the complexities involved in coupling modulation. Here, we develop a universal coupling control scheme via reservoir engineering, achieving conservative, dissipative, and mixed topologies in an optical waveguide array. Contrary to the belief that topological modes are disorder resistant, we found that topological dissipative modes are highly sensitive to initial excitations and noise. This sensitivity is due to their residence within the complex band gap, facilitating the excitation and preservation of bulk modes with lower loss. We also propose a method to control the degree of topological robustness and even stabilize these sensitive topological states by selectively managing dissipative potentials. Our Letter offers new insights into the dissipative dynamics of topological states, paving the way for wave coherent manipulation and diffusion transport on photonic chips.

Thermal metamaterials represent a transformative paradigm in modern physics, synergizing thermodynamic principles with metamaterial engineering to master heat flow at will. As next-generation technologies demand multi-scale thermal control, this field urgently requires systematic frameworks to unify its multidisciplinary advances. Curated through a global collaboration involving over 50 specialists across 25 subdisciplines, this review primarily summarizes two decades of advancements, ranging from theoretical breakthroughs to functional implementations. The review reveals groundbreaking innovations in heat manipulation through the exploration of both classical and non-classical transport regimes, topological thermal control mechanisms, and quantum-informed phonon engineering strategies. By bridging physical insights like non-Hermitian thermal dynamics and valleytronic phonon transport with cutting-edge applications, we demonstrate paradigm-shifting capabilities: environment-adaptive thermal cloaks, AI-optimized metamaterials, and nonlinear thermal circuits enabling heat-based computation. Experimental milestones include 3D thermal null media with reconfigurable invisibility and thermal designs breaking classical conductivity limits. This collaborative effort establishes an indispensable roadmap for physicists, highlighting pathways to quantum thermal management, entropy-controlled energy systems, and topological devices. As thermal metamaterials transition from laboratory marvels to technological cornerstones, this work provides the foundational lexicon and design principles for the coming era of intelligent thermal matter.

In this study, we innovatively modeled photon-enhanced thermionic emission (PETE) devices, incorporating positive ion injection and bidirectional discharge's effects on the space charge barrier simultaneously. Compared to previous models, our model allows the positive ion distribution function to be compatible with scenarios in which the anode motive is either higher or lower than the cathode motive, and also adapts to significant anode discharge. Through numerical simulations and parametric analyses, we found that: (1) As the ratio of the positive ion increases, the capability for space charge neutralization becomes stronger. (2) The lower the electron affinity is, the smaller the ratio of positive ions are required. (3) When the anode temperature is higher or the anode work function is lower, the impact of reverse discharge on the net current density is more pronounced. Conversely, when the anode temperature is higher or the anode work function is greater, the ratio of positive ions required to achieve complete space charge neutralization increases. This study further elucidates the mechanisms and characteristics of space charge neutralization effects in PETE devices, providing a theoretical foundation for optimizing their design. Additionally, the accompanying theory and algorithm possess the potential to spark innovative research across diverse fields.

The precision of nonequilibrium thermodynamic systems is fundamentally limited, yet how quantum coherence shapes these limits remains largely unexplored. A general theoretical framework is introduced that explicitly links quantum coherence to thermodynamic uncertainty relations. By defining a coherence-sensitive measure, it is shown that quantum effects can relax the classical trade-off between the entropy production and the current fluctuations, enabling the precision beyond classical bounds. Application to a three-level quantum maser illustrates the framework in a concrete setting. These results establish quantum coherence as a genuine thermodynamic resource and provide a unified perspective connecting classical and quantum approaches to nonequilibrium thermodynamics.

Two types of hot-carrier photocatalysts (HCPCs) based on quantum well and quantum dot energy-selective contacts (ESCs) have been proposed. The transport equations for both types of devices are derived using the ballistic transport theory. The electrocatalytic behavior of reaction sites in water splitting is modeled by using the Butler–Volmer equation. The impacts of the ESC parameters, including the extraction energy level and the transmission energy width, on the performance of HCPC devices have been investigated. The results indicate that the thermal losses from non-ideal ESCs significantly limit HCPC efficiency, which can be enhanced by optimizing ESC parameters. Comparisons show that HCPCs with quantum dot ESCs outperform those with quantum well ESCs, owing to their superior carrier transport capability and lower thermal loss rates. For an absorber bandgap of 1 eV, the optimized solar-to-H2 energy conversion efficiencies of the two HCPCs reach 62.34% and 64.93%, respectively, highlighting the promising application potential of these catalysts.

The bidirectional space charge effects in photon-enhanced thermionic emission (PETE) devices are investigated systematically. First, we precisely determine the carrier concentrations and cathode temperatures by taking into account the electron recycling effect, energy balance constraints, and space charge effects arising from the concurrent discharge of the cathode and anode. Next, we analyze the impact of critical parameters, including anode properties and operating conditions, on the space charge barrier distribution and the overall performance of the device. The results demonstrate that the impact of reverse discharge on the net current becomes more pronounced when the PETE device operates at high anode temperatures, low anode work functions, and with a moderate solar concentration ratio and gap width. This discovery not only deepens our understanding of the bidirectional space charge effect, but also provides valuable guidance for the future optimization of PETE device performance.

Pursuing significant thermal rectification effect with minimal temperature differences is critical for thermal rectifiers.While asymmetric structures enable spectral matching,they inherently limit thermal rectification performance.To ad-dress this issue,we developed a thermal rectification structure comprising a current-biased graphene-coated silicon carbide(SiC)substrate paired with another graphene-coated SiC substrate separated by a nanoscale vacuum gap.A current-biased graphene sheet generates nonreciprocal effect that actively modulates radiative energy transfer.Our theoretical framework demonstrates that the current-biased graphene achieves a high thermal diode efficiency even under a modest temperature difference.Remarkably,the thermal diode efficiency exceeds 0.8 at a temperature difference of just 100 K(between 300 K and 400 K).These findings highlight the synergistic enhancement from graphene coatings and current biasing,providing a viable strategy for nanoscale thermal management applications.

In this paper, we examine the power and efficiency of the thermionic device utilizing the Nernst effect, with a specific focus on its potential application as an engine. The device operates by utilizing the vertical heat current to generate a horizontal particle current against the chemical potential. By considering the influence of a strong magnetic field, we derive analytical expressions for the current and heat flux. These expressions are dependent on the temperature and chemical potential of heat reservoirs, providing valuable insights into the device performance. The impact of driving temperatures on the performance of the thermionic engine has been assessed through numerical analysis. The research findings will guide the experimental design of Nernst-based thermionic engines.

According to the characteristic that the polytropic exponent in the equation of the polytropic process of ideal gases remains the same, it is expounded that the specific heat of the polytropic process is closely related to the specific heat at constant volume of ideal gases. When the specific heat at constant volume of ideal gases is constant, all the thermodynamic processes with constant specific heat are classified as the polytropic processes of ideal gases, and there is no forbidden area for the value of the polytropic exponent. However, when the specific heat at constant volume of ideal gases varies with temperature, the thermodynamic processes with constant specific heat do not belong to polytropic processes, such as the adiabatic process with the zero specific being not a polytropic process, and there is a forbidden area for the value of the polytropic exponent. Only when the specific heat of a thermodynamic process resembles the specific heat at constant volume of ideal gases and has the same temperature dependency, can the thermodynamic process be a polytropic process of ideal gases. The basic characteristic of the polytropic process of ideal gases is that the difference between the specific heat of the process and the specific heat at constant volume is constant.

We establish a finite-time quantum tricycle driven by an external field and investigate its thermodynamic performance in the slow-driving regime. By developing a perturbative expansion of heat with respect to operation time, we capture the dynamics of heat exchange processes beyond the quasistatic limit. Within a geometric framework, we derive fundamental bounds on trade-offs between the cooling rate, coefficient of performance, and dissipation, governed by the thermodynamic length and trajectory geometry in control space. Our findings unveil intrinsic limits to the performance of quantum thermal machines and highlight the role of geometry in shaping finite-time thermodynamics. This work advances the fundamental understanding of quantum thermodynamic processes and offers guiding principles for the design of next-generation quantum technologies.