Figure 1
Simple model for a heat engine. QH is input heat from a hot source to the engine, QC is the heat rejected to the colder environment (entropy sink) and W is the work output.
Source publication
The advantages of quantum effects in several technologies, such as computation and communication, have already been well appreciated. Some devices, such as quantum computers and communication links, exhibiting superiority to their classical counterparts, have been demonstrated. The close relationship between information and energy motivates us to e...
Contexts in source publication
Context 1
... Q H and Q C are the heat received and rejected in the engine operation and W is the work produced in the engine cycle, as illustrated in Figure 1. Simple model for a heat engine. ...
Context 2
... a strategy allows us to establish the efficiency of such information fueled engines compared to the Carnot bound. The basic idea is to consider the source and the sink in Figure 1 as information reservoirs and to use a quantum system as the engine's working substance. The work output of the cycle becomes then analog of a calculation or a computational process. ...
Context 3
... problem of thermalization of a composite system consisting of a target qubit (the system) that randomly and repeatedly interacts with a cluster of N identical spin-1/2 (qubit) particles is examined in Ref. [173,177]. The system is illustrated in Figure 10. The target qubit's evolution is found to be equivalent to the master equation of a coherently driven two-level atom in a squeezed thermal bath. ...
Context 4
... work output depends on the number of the atoms quadratically, due to the superradiance [184], where a cluster can radiate quadratically faster than a single atom. The model is illustrated in Figure 11. Superradiance (SR) is given as a cooperative emission of light from an ensemble of excited two-level atoms in a small volume relative to emission wavelength [184]. ...
Context 5
... is a critical size of the cluster for which quadratic enhancement in the work output can still be obtained even in the presence of a quadratic increase in the decoherence factor. We can represent coherences between N atomic energy levels as a complete graph as in Figure 12, which can Figure 11. A cavity field pumped by a beam of N -atom clusters in atomic coherent or Dicke states reaches a steady state, a coherent thermal state. ...
Context 6
... is a critical size of the cluster for which quadratic enhancement in the work output can still be obtained even in the presence of a quadratic increase in the decoherence factor. We can represent coherences between N atomic energy levels as a complete graph as in Figure 12, which can Figure 11. A cavity field pumped by a beam of N -atom clusters in atomic coherent or Dicke states reaches a steady state, a coherent thermal state. ...
Context 7
... to the result of Ref. [179], there is a critical size of such a quantum fuel molecule, after which further increase of the size would give negative yields, rapidly decreasing the efficiency and work output. Figure 12. Representation of coherences between N atomic energy levels in a multilevel atom or an atomic cluster as a complete graph. ...
Context 8
... can be compared to the microeconomical law of diminishing returns [194], plotted in Figure 13. ...
Context 9
... finite size systems with a varying number of particles are further examined in [174] from the perspective of their generation using thermal and nonthermal means. The system subject to thermal charging of coherences is illustrated in Figure 14a. A pair of two-level atoms is initially prepared in a state with an amount of heat exchange coherence C L . ...
Context 10
... role of dipolar interactions between the particles is shown to be not critical in thermal induction of coherence. The discharge of stored coherences Figure 13. Microeconomical law of diminishing returns. ...
Context 11
... heat is shown in Figure 14b, where a single two-level atom collides sequentially with a pair of atoms with coherence C H . Some amount of the energy cost to generate coherences in the initial state can be harvested back as heat. ...
Context 12
... the single-atom reaches a steady state that is a thermal state with an effective temperature of T eff . This temperature depends on the coherence C H of the subenvironment atomic pairs as illustrated in Figure 14c. [174])A pair of two-level atoms initially in a state with (lower) coherence CL can be transformed into another state with higher coherence CH > CL by collective interaction with a thermal bath. ...
Context 13
... N -element spin-star network, illustrated in Figure 15, has been proposed as a quantum fuel to power up a photonic Carnot engine [177]. Previously, it has been shown that using individual qubit in a pair yields different work output than using the pair as whole as quantum fuel [195]. ...
Similar publications
The Peierls instability in one-dimensional electron-phonon systems is known to be qualitatively well described by the Mean-Field theory, however the related self-consistent problem so far has only been able to predict a partial suppression of the transition even with proper account of classical lattice fluctuations. Here the Hartree-Fock approximat...
Citations
... In these engines, entangled particles are used to extract work from heat baths, and the process is driven by a violation of local realism, a fundamental assumption in classical physics. The exploration of quantum thermodynamics and the potential of quantum coherence engines has been significantly advanced by recent works such as Park et al. (2013) [23] and Ozdemir and Müstecaplolu (2020) [24], which highlight the innovative use of quantum information to drive heat engines and the exploration of quantum coherence in operational engines. These theoretical frameworks extend the concept of traditional heat engines into the quantum realm, offering new insights into the role of quantum entanglement and coherence in energy conversion processes. ...
This study explores ground-breaking methods for improving engine efficiency by combining cutting-edge materials, theoretical frameworks, and alternative energy paradigms. The paper primarily offers a cohesive framework, built from our variational method which combines thermal and entropic engines. We investigate the fabrication of hydrophobic and other functionally specific surfaces using nanomaterials and sophisticated surface engineering techniques that efficiently utilize entropy gradient forces. Additionally, this publication explores the fields of quantum-based propulsion systems and information-burning engines, creating a connecting link between theoretical foundations and real-world technical implementations. The study emphasizes the multifaceted character of engine research and its crucial role in shaping a future in which sustainability and efficiency are intimately connected.
... Recent studies in quantum thermodynamics have provided a deeper understanding of the interplay between heat, work, quantum information, and, specifically, quantum coherence [44][45][46][47][48]. In line with these quantum thermodynamical perspectives, several schemes have been proposed in quantum thermometry that exploit nonclassical features to enhance thermal sensitivity [16,19,[26][27][28][29][30]41,[49][50][51][52][53]. ...
The precise measurement of low temperatures is significant for both the fundamental understanding of physical processes and technological applications. In this work, we present a method for low-temperature measurement that improves thermal range and sensitivity by generating quantum coherence in a thermometer probe. Typically, in temperature measurements, the probes thermalize with the sample being measured. However, we use a two-level quantum system, or qubit, as our probe and prevent direct probe access to the sample by introducing a set of ancilla qubits as an interface. We describe the open system dynamics of the probe using a global master equation and demonstrate that while the ancilla-probe system thermalizes with the sample, the probe per se evolves into a nonthermal steady state due to nonlocal dissipation channels. The populations and coherences of this steady state depend on the sample temperature, allowing for precise and wide-range low-temperature estimation. We characterize the thermometric performance of the method using quantum Fisher information and show that the quantum Fisher information can exhibit multiple and higher peaks at different low temperatures with increasing quantum coherence and the number of ancilla qubits. Our analysis reveals that the proposed approach, using a nonthermal qubit thermometer probe with temperature-dependent quantum coherence generated by a multiple qubit interface between a thermal sample and the probe qubit, can enhance the sensitivity of temperature estimation and broaden the measurable low-temperature range.
... Of particular significance is the efficiency at maximum power, which was studied by Curzon and Ahlborn in their seminal paper [2]. Currently, there is ongoing research in quantum heat engines and refrigerators [3][4][5][6][7]. Since the pioneering work by Scovil and Schulz-DuBois [8], quantum heat engines have been extensively studied theoretically , and successful experimental demonstrations have been recently reported [40][41][42][43][44][45][46][47]. ...
We investigate the energetic advantage of accelerating a quantum harmonic oscillator Otto engine by use of shortcuts to adiabaticity (for the expansion and compression strokes) and to equilibrium (for the hot isochore), by means of counter-diabatic (CD) driving. By comparing various protocols with and without CD driving, we find that, applying both type of shortcuts leads to enhanced power and efficiency even after the driving costs are taken into account. The hybrid protocol not only retains its advantage in the limit cycle, but also recovers engine functionality (i.e., a positive power output) in parameter regimes where an uncontrolled, finite-time Otto cycle fails. We show that controlling three strokes of the cycle leads to an overall improvement of the performance metrics compared with controlling only the two adiabatic strokes. Moreover, we numerically calculate the limit cycle behavior of the engine and show that the engines with accelerated isochoric and adiabatic strokes display a superior power output in this mode of operation.
... The insight that heat and quantum coherence are convertible represents a significant advance in the realm of quantum thermodynamics [14][15][16][17][18][19]. Specifically, a form of energetic quantum coherence responsible for generating heat arises through the dynamical framework rooted in open quantum systems theory [20][21][22][23][24]. ...
The resource theory of quantum thermodynamics has emerged as a powerful tool for exploring the out-of-equilibrium dynamics of microscopic and highly correlated systems. Recently, it has been employed in photoisomerization, a mechanism facilitating vision through the isomerism of the photo receptor protein rhodopsin, to elucidate the fundamental limits of efficiency inherent in this physical process. Limited attention has been given to the impact of energetic quantum coherences in this process, as these coherences do not influence the energy level populations within an individual molecule subjected to thermal operations. However, a specific type of energetic quantum coherences can impact the energy level populations in the scenario involving two or more molecules. In this study, we examine the case of two molecules undergoing photoisomerization to show that energetic quantum coherence can function as a resource that amplifies the efficiency of photoisomerization. These insights offer evidence for the role of energetic quantum coherence as a key resource in the realm of quantum thermodynamics at mesoscopic scales.
... The cooling factor displays an increase as the ratio of n m /n a rises. This observation is compatible with the common thermodynamics notion which is also applicable in the quantum regime [108] that higher cooling efficiency is achieved under the higher temperature contrast, which in our case corresponds to n a ≪ n m . ...
Motivated by the very recent experimental breakthroughs, we theoretically explore optomechanical cooling and squeezing in a non-Hermitian ternary coupled system composed of an optical cavity and two mechanical resonators. A closed-contour interaction is formed embodied by a global phase that constitutes a synthetic $U(1)$ gauge field. We illustrate over a realistic parameter set the cooling of either mechanical resonator by the synthetic field. A stark disparity between the optical heating versus mechanical cooling factors is observed which is rooted in the high damping constant ratio of the optical and mechanical oscillators. Additionally, an amplitude modulation is imposed over the cavity-pumping laser to attain mechanical squeezing. A set of complementary numerical approaches are employed: the time-integrator method for the instantaneous behavior, and the Floquet technique for the steady-state or modulated characteristics. The latter is further supported by the James' effective Hamiltonian method which explicitly reveals the role of upper-sideband modulation in squeezing. We identify the symmetry, namely, the invariance of the system under simultaneous swapping of the two mechanical resonators together with closed-loop phase reversal, which enables targeted cooling or squeezing of either mechanical resonator. We also elaborate on the intricate role of proximity to the exceptional points on the enhancement of cooling and squeezing.
... Of particular significance is the efficiency at maximum power, which was studied by Curzon and Ahlborn in their seminal paper [2]. Currently, there is ongoing research in quantum heat engines and refrigerators [3][4][5][6][7]. Since the pioneering work by Scovil and Schulz-DuBois [8], quantum heat engines have been extensively studied theoretically , and successful experimental demonstrations have been recently reported [40][41][42][43][44][45][46][47]. ...
We investigate the energetic advantage of accelerating a quantum harmonic oscillator Otto engine by use of shortcuts to adiabaticity (for the power and compression strokes) and to equilibrium (for the hot isochore), by means of counter-diabatic (CD) driving. By comparing various protocols with and without CD driving, we find that, applying both type of shortcuts leads to enhanced power and efficiency even after the driving costs are taken into account. The hybrid protocol not only retains its advantage in the limit cycle, but also recovers engine functionality (i.e., a positive power output) in parameter regimes where an uncontrolled, finite-time Otto cycle fails. We show that controlling three strokes of the cycle leads to an overall improvement of the performance metrics compared with controlling only the two adiabatic strokes. Moreover, we numerically calculate the limit cycle behavior of the engine and show that the engines with accelerated isochoric and adiabatic strokes display a superior power output in this mode of operation.
... Generation of quantum entanglement or coherence in a quantum system using a thermal gradient can be envisioned as a quantum heat engine [54,35,53], which is the practical application of emerging field of quantum thermodynamics [40,25]. M. Scully argued that quantum coherence could be exploited to enhance photovoltaic efficiencies [48] and efficiency of a photonic Carnot engine [50]. ...
We present a short overview of quantum entanglement generation and preservation in a steady state. In addition to the focus on quantum entanglement stabilization, we briefly discuss the same objective for steady-state quantum coherence. The overview classifies the approaches into two main categories: hybrid drive and dissipation methods and purely dissipative schemes. Furthermore, purely dissipative schemes are discussed under two subclasses of equilibrium and nonequilibrium environments. The significance of the dissipative route to sustained quantum entanglement and challenges against it are pointed out. Besides the value of steady-state entanglement for existing quantum technologies, quantum computation, communication, sensing, and simulation, its unique opportunities for emerging and future quantum technology applications, particularly quantum heat engines and quantum energy processing, are discussed.
... Quantum thermodynamics investigates the applicability of laws of thermodynamics and their possible generalizations in the realm of quantum mechanics [1][2][3][4][5][6][7]. Quantum heat engines (QHEs) serve as test beds for fundamental discussions and practical applications of quantum thermodynamics. ...
... Quantum thermodynamics investigates the applicability of laws of thermodynamics and their possible generalizations in the realm of quantum mechanics [1][2][3][4][5][6][7]. Quantum heat engines (QHEs) serve as test beds for fundamental discussions and practical applications of quantum thermodynamics. ...
Enantiomers are chiral molecules that exist in right-handed and left-handed conformations. For the discrimination between left- and right-handed molecules, optical techniques of enantiomers detection are widely employed. However, identical spectra of enantiomers make enantiomer detection a very challenging task. Here, we investigate the possibility of exploiting thermodynamic processes for enantiomer detection. In particular, we employ a quantum Otto cycle, in which a chiral molecule described by a three-level system with cyclic optical transitions is considered a working medium. Each energy transition of the three-level system is coupled with an external laser drive. By changing the phase of these drives during the adiabatic stages of the Otto cycle, we find that left- and right-handed molecules work as a heat engine and heat pump, respectively. In addition, if the detuning of the laser drives is varied during adiabatic strokes of the cycle, both left- and right-handed molecules work as heat engines. However, the molecules can still be distinguished because the extracted work and efficiency are quantitatively very different in both cases. Accordingly, left and right-handed molecules can be distinguished by evaluating the work distribution in the Otto cycle.
... Studies in quantum thermodynamics [37][38][39][40][41] revealed deeper insight into the interplay between heat, work, quantum information, and in particular, quantum coherence [42][43][44][45][46][47][48][49][50][51][52]. In parallel with the quantum thermodynamical perspectives of quantum coherence, several schemes have been proposed in quantum thermometry to exploit nonclassical features to enhance thermal sensitivity [16, 19, 24-28, 34, 53-57]. ...
Precise estimation of low temperature is a question of both fundamental and technological significance. We address this question by presenting a low-temperature measurement scheme with enhanced thermal sensitivity due to quantum coherence generation in a thermometer probe. Probes are expected to thermalize with the sample to be measured in typical temperature measurements. In our scheme, we consider a two-level quantum system (qubit) as our probe and forbid direct probe access to the sample by using a set of ancilla qubits as an interface. By deriving a global master equation to describe the open system dynamics of the probe, we show that while the whole ancilla-probe system thermalizes with the sample, the probe per se evolves under nonlocal dissipation channels into a non-thermal steady state whose populations and coherences depend on the sample temperature. We characterize the thermometric performance of the low-temperature measurement using quantum Fisher information and we find that multiple and higher peaks at different low temperatures can emerge in the quantum Fisher information with increasing quantum coherence and number of ancilla qubits. Our analysis reveals that using non-thermal quantum probes, specifically quantum coherence generation in a qubit thermometer by a multiple qubit interface between a thermal sample and the probe qubit, can enhance the sensitivity of temperature estimation and broaden the measurable low temperatures range.
