We analyze the entropy production and maximal extractable work from a squeezed thermal reservoir. The nonequilibrium quantum nature of reservoir induces an transfer with coherent contribution while modifying its part, allowing extraction single reservoir, as well great improvements in power efficiency for heat engines. Introducing modified Otto cycle, our approach fully characterizes operational regimes forbidden standard case, such refrigeration at same time, accompanied by efficiencies...

We analyze the production of entropy along nonequilibrium processes in quantum systems coupled to generic environments. First, we show that due final measurements and loss correlations obeys a fluctuation theorem detailed integral forms. Second, discuss decomposition into two positive contributions, adiabatic nonadiabatic, based on existence invariant states local dynamics. Fluctuation theorems for both contributions hold only evolutions verifying specific condition origin. illustrate our...

We consider the phenomenon of mutual synchronization in a fundamental quantum system two detuned harmonic oscillators dissipating into environment. identify conditions leading to this spontaneous showing that ability synchronize is related existence disparate decay rates and accompanied by robust discord information between oscillators, preventing leak from system.

We derive a general fluctuation theorem for quantum maps. The applies to broad class of dynamics, such as unitary evolution, decoherence, thermalization, and other types evolution open systems. reproduces well-known theorems in single simplified framework extends the Hatano-Sasa nonequilibrium processes. Moreover, it helps elucidate physical nature environment that induces given dynamics an system.

We analyze the role of indirect quantum measurements in work extraction from systems nonequilibrium states. In particular, we focus on that can be obtained by exploiting correlations shared between system interest and an additional ancilla, where measurement backaction introduces a nontrivial thermodynamic tradeoff. present optimal state-dependent protocols for extracting both classical correlations, latter being measured discord. show that, while content fully extracted performing local...

We introduce and realize demons that follow a customary gambling strategy to stop nonequilibrium process at stochastic times. derive second-law-like inequalities for the average work done in presence of gambling, universal stopping-time fluctuation relations classical quantum nonstationary processes. test experimentally our results single-electron box, where an electrostatic potential drives dynamics individual electrons tunneling into metallic island. also discuss role coherence measuring...

The thermodynamics of quantum systems driven out equilibrium has attracted increasing attention in the last decade, connection with information and statistical physics, a focus on non-classical signatures. While first approach can deal average quantities over ensembles, order to establish impact environmental fluctuations during evolution, continuous measurement open system is required. Here, we provide an introduction general theoretical framework interpret for whose nonequilibrium...

Developing a thermodynamic theory of computation is challenging task at the interface nonequilibrium thermodynamics and computer science. In particular, this requires dealing with difficulties such as stochastic halting times, unidirectional (possibly deterministic) transitions, restricted initial conditions, features common in real-world computers. Here, we present framework which tackles all by extending martingale to generic nonstationary Markovian processes, including those broken...

Synchronization is one of the paradigmatic phenomena in study complex systems. It has been explored theoretically and experimentally mostly to understand natural phenomena, but also view technological applications. Although several mechanisms conditions for synchronous behavior spatially extended systems networks have identified, emergence this phenomenon largely unexplored quantum until very recently. Here we discuss synchronization different harmonic oscillators relaxing towards a...

Multilevel autonomous quantum thermal machines are discussed. In particular, we explore the relationship between size of machine (captured by Hilbert space dimension) and performance machine. Using concepts virtual qubits temperatures, show that higher dimensional can outperform smaller ones. For instance, considering refrigerators with more levels, lower temperatures be achieved, as well power. We discuss optimal design for a given dimension. As consequence obtain statement third law in...

We explore the perspective of considering squeezed thermal reservoir as an equilibrium in a generalized Gibbs ensemble with two noncommuting conserved quantities. outline main properties such terms exchange energy, both heat and work, entropy, giving some key examples to clarify its physical interpretation. This allows for correct insightful interpretation all thermodynamical features reservoir, well other similar nonthermal reservoirs, including characterization reversibility first second...

The characterization and control of quantum effects in the performance thermodynamic tasks may open new avenues for small thermal machines working nanoscale. We study impact coherence energy basis operation a machine which can act either as heat engine or refrigerator. show that input enhance allow it to operate otherwise forbidden regimes. Moreover, our results also indicate that, some cases, be detrimental, rendering optimization particular models crucial task benefiting from...

Modern quantum experiments provide examples of transport with noncommuting quantities, offering a tool to understand the interplay between thermal and effects. Here we set forth theory for non-Abelian in linear response regime. Our key insight is use generalized Gibbs ensembles charges as basic building blocks strict charge-preserving unitaries collisional setup. The framework then built using model two reservoirs. We show that coefficients obey Onsager reciprocity. Moreover, find coherence,...

The authors of this paper investigate the impact collective effects on performance quantum heat engines, specifically stability output power with respect to fluctuations. They show a regime in which one can have enhanced for increasing but finite system sizes, while maintaining constant efficiency, contradicts classical bound based thermodynamic uncertainty relation.

Nonequilibrium effects may have a profound impact on the performance of thermal devices performing thermodynamic tasks such as refrigeration or heat pumping. The possibility enhancing operations by means quantum coherence is particular interest but requires an adequate characterization and work at level. In this work, we demonstrate that presence even small amounts in reservoirs powering three-terminal machine, enables appearance combined, hybrid modes operation, where either different...

Abstract From the perspective of quantum thermodynamics, realisable measurements cost work and result in measurement devices that are not perfectly correlated with measured systems. We investigate consequences for estimation non-equilibrium processes fundamental structure fluctuations when one assumes non-ideal. show obtaining estimates their statistical moments at finite implies an imperfection themselves: more accurate incur higher costs. Our results provide a qualitative relation between...

This work studies synchronization along single quantum trajectories of two van der Pol oscillators under homodyne detection, characterizing the phenomenon and finding a new link between statistics entanglement.

Thermal machines perform useful tasks--such as producing work, cooling, or heating--by exchanging energy, and possibly additional conserved quantities such particles, with reservoirs. Here we consider thermal that more than one task simultaneously, terming these "hybrid machines". We outline their restrictions imposed by the laws of thermodynamics quantify performance in terms efficiencies. To illustrate full potential, reservoirs feature multiple quantities, described generalized Gibbs...

Abstract We explore the possibility of enhancing performance small thermal machines by presence common noise sources. In particular, we study a prototypical model for an autonomous quantum refrigerator comprised three qubits coupled to reservoirs at different temperatures. Our results show that engineering coupling act as environments lead relevant improvements in performance. The enhancements arrive almost double cooling power original fridge without compromising its efficiency. greater are...

We present a model for an autonomous quantum thermal machine comprised of two qubits capable manipulating and even amplifying the local coherence in non-degenerate external system. The uses only resources, namely, contact with heat baths at different temperatures, system has non-zero initial amount coherence. method we propose allows interconversion between energy, both work heat, configuration working out-of-equilibrium conditions. This raises interesting questions about role fundamental...

Microscopic physical laws are time-symmetric, hence, a priori there exists no preferential temporal direction. However, the second law of thermodynamics allows one to associate "forward" direction positive variation total entropy produced in thermodynamic process, and negative with its "time-reversal" counterpart. This definition axis is normally considered apply both classical quantum contexts. Yet, physics admits also superpositions between forward time-reversal processes, whereby arrow...

The thermodynamic behavior of Markovian open quantum systems can be described at the level fluctuations by using continuous monitoring approaches. However, practical applications require assessing imperfect detection schemes, where definition main quantities becomes subtle and universal fluctuation relations are unknown. Here, we fill this gap deriving a relation that links entropy production information-theoretical irreversibility along single trajectories in inefficient setups. This...

We analyze the symmetries in an open quantum system composed by three coupled and detuned harmonic oscillators presence of a common heat bath. It is shown analytically how to engineer couplings frequencies so as have several degrees freedom unaffected decoherence, irrespective specific spectral density or initial state This partial thermalization allows observing asymptotic entanglement at moderate temperatures, even nonresonant case. latter feature cannot be seen simpler situation only two...

We develop a martingale theory to describe fluctuations of entropy production for open quantum systems in nonequilbrium steady states. Using the formalism jump trajectories, we identify decomposition into an exponential and purely term, both obeying integral fluctuation theorems. An important consequence this approach is derivation set genuine universal results stopping-time infimum statistics stochastic production. Finally complement general with numerical simulations qubit system.

When a quantum dot is attached to metallic reservoir and superconducting contact, Andreev processes lead finite subgap current at the normal creation or destruction of Cooper pairs. reflection engines profit from pairs provide work needed set charge normal-conductor contact generating electrical power. For this power-transduction device, high power large efficiencies in mechanically enhanced regimes are demonstrated. There thermodynamic tradeoff relations between power, efficiency,...