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The variations of THC J SS as θ and λ L . (a) The phase diagram of the quantum machine working as a multifunctional device in the parametric regimes of θ and λ L : RR, SR, HPSR, HPIR and HPAR; (b) the variations of J SS with λ L for some fixed relative phases θ. The other parameters are the same as the ones in Figure 3. The purple (white) dotted line in (a) represents working points with J SS = J re f (J SS = 0) also corresponding to the purple (black) solid line in (b).
Source publication
We study a scheme of thermal management where a three-qubit system assisted with a coherent auxiliary bath (CAB) is employed to implement heat management on a target thermal bath (TTB). We consider the CAB/TTB being ensemble of coherent/thermal two-level atoms (TLAs), and within the framework of collision model investigate the characteristics of st...
Contexts in source publication
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... is noted that the periods T λ = π/2 and T θ = π are independent of the other parameters in our model. In order to demonstrate the characteristics of J SS and the thermal functions of quantum machine clearly, the variation of J SS in a single period with 0 ≤ θ ≤ T θ and 0 ≤ λ L ≤ T λ is shown in Figure 4 where all the other parameters are the same as that given in Figure 3. In Figure 4a the multifunctional regions of quantum machine have been shown, and Figure 4b for the corresponding variations of J SS for some fixed θ, θ/π = {0, 0.15 , 0.30 0.45, 0.60, 0.75, 0.90, 1.0}. ...
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... order to demonstrate the characteristics of J SS and the thermal functions of quantum machine clearly, the variation of J SS in a single period with 0 ≤ θ ≤ T θ and 0 ≤ λ L ≤ T λ is shown in Figure 4 where all the other parameters are the same as that given in Figure 3. In Figure 4a the multifunctional regions of quantum machine have been shown, and Figure 4b for the corresponding variations of J SS for some fixed θ, θ/π = {0, 0.15 , 0.30 0.45, 0.60, 0.75, 0.90, 1.0}. From Figure 4a it can be seen that the quantum machine could work as a multifunctional thermal device, and the specific function relies on the values of parameters θ and λ L . ...
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... order to demonstrate the characteristics of J SS and the thermal functions of quantum machine clearly, the variation of J SS in a single period with 0 ≤ θ ≤ T θ and 0 ≤ λ L ≤ T λ is shown in Figure 4 where all the other parameters are the same as that given in Figure 3. In Figure 4a the multifunctional regions of quantum machine have been shown, and Figure 4b for the corresponding variations of J SS for some fixed θ, θ/π = {0, 0.15 , 0.30 0.45, 0.60, 0.75, 0.90, 1.0}. From Figure 4a it can be seen that the quantum machine could work as a multifunctional thermal device, and the specific function relies on the values of parameters θ and λ L . ...
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... Figure 4a the multifunctional regions of quantum machine have been shown, and Figure 4b for the corresponding variations of J SS for some fixed θ, θ/π = {0, 0.15 , 0.30 0.45, 0.60, 0.75, 0.90, 1.0}. From Figure 4a it can be seen that the quantum machine could work as a multifunctional thermal device, and the specific function relies on the values of parameters θ and λ L . Specifically, in terms of the features of J SS in Figure 4a, the whole parametric space of 0 ≤ λ θ ≤ T θ and 0 ≤ θ ≤ T θ is divided into several different function regions: switcher region (SR) (the white dotted line for J SS = 0), refrigeration region (RR) (the region surrounded by the white dotted line for J SS < 0), heat pump invariable region (HPIR) (the purple dotted line for J SS = J ref ), heat pump suppression region (HPSR) (the middle region between the white and purple dotted lines for J ref > J SS > 0) and heat pump amplification region (HPAR) (the left-side region of purple line for J SS > J ref ). ...
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... Figure 4a it can be seen that the quantum machine could work as a multifunctional thermal device, and the specific function relies on the values of parameters θ and λ L . Specifically, in terms of the features of J SS in Figure 4a, the whole parametric space of 0 ≤ λ θ ≤ T θ and 0 ≤ θ ≤ T θ is divided into several different function regions: switcher region (SR) (the white dotted line for J SS = 0), refrigeration region (RR) (the region surrounded by the white dotted line for J SS < 0), heat pump invariable region (HPIR) (the purple dotted line for J SS = J ref ), heat pump suppression region (HPSR) (the middle region between the white and purple dotted lines for J ref > J SS > 0) and heat pump amplification region (HPAR) (the left-side region of purple line for J SS > J ref ). In addition, Figure 4a also demonstrates several obvious features. ...
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... in terms of the features of J SS in Figure 4a, the whole parametric space of 0 ≤ λ θ ≤ T θ and 0 ≤ θ ≤ T θ is divided into several different function regions: switcher region (SR) (the white dotted line for J SS = 0), refrigeration region (RR) (the region surrounded by the white dotted line for J SS < 0), heat pump invariable region (HPIR) (the purple dotted line for J SS = J ref ), heat pump suppression region (HPSR) (the middle region between the white and purple dotted lines for J ref > J SS > 0) and heat pump amplification region (HPAR) (the left-side region of purple line for J SS > J ref ). In addition, Figure 4a also demonstrates several obvious features. First, each functional region of HPAR, HPIR, HPSR, SR and RR distributes in a certain continuous parametric space of λ L and θ. ...
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... each functional region of HPAR, HPIR, HPSR, SR and RR distributes in a certain continuous parametric space of λ L and θ. Second, for the convenient descriptions of different functional regions we denote λ u as the coupling strength of HPIR (the purple dotted line at the middle region in Figure 4a), satisfying J SS (θ, λ u ) = J SS (θ, λ L = 0) = J ref (note that J SS (θ, λ u ) = J ref does not mean the redefinition of the reference current J ref , and only indicates the values of THC at some certain working points (θ, λ u ) on the purple dotted line are the same as reference current J ref (λ L = 0) as defined before). One can see that the HPAR only lies in the region of λ L below λ u , (i.e., the region of λ L < λ u ), and other function regions of HPSR, SR and RR for λ L over λ u , (i.e., the region of λ L > λ u ). ...
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... Figure 4b, one can see some specific behaviors of J SS varying with θ and λ L . Firstly, for a finite relative phase θ the THC J SS always behaves as a sine-like function with respect to λ L . ...
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... we mainly concern the influences of coherence magnitude α on the THC J SS for a fixed relative phase θ S (here, θ S = 0.45π corresponds to the largest modulation width of J SS (seen in Figure 4a or Figure 4b) ...
Citations
... To influence quantum heat machines, quantum coherence and correlations can be applied directly in the working substance [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] or put into the reservoir to form a nonthermal reservoir. This perspective has been extensively studied [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] since the pioneering work by Scully et al, which showed that by virtue of nonthermal reservoir with coherence, the efficiency of a photonic Carnot engine can be increased to surpass the limit imposed by the thermal reservoir [41]. In this case, the coherence or correlations can be deemed as thermodynamic resources, or alternatively, a type of fuel being able to power the machines [26][27][28]. ...
In this work, we investigate the impact of energetic coherence in nonthermal reservoirs on the performance of the Otto cycle. We first focus on the situation where the working substance is a qubit. Due to the existence of coherence of nonthermal reservoir, various anomalous operating regimes such as the engine and refrigerator with efficiencies exceeding Carnot limits, as well as the hybrid refrigerator that can simultaneously achieve cooling and supplying work to an external agent, can occur. We demonstrate that the energetic coherence of the system’s steady state plays a significant role in determining the cycle’s functions by adding an additional stroke implementing dephasing and phase modulation operations in the cycle. The energetic coherence of the system is necessary to trigger the reservoir’s coherence to exert influences on the cycle. We decompose the thermodynamic quantities to the components arising from the populations and coherence of the system, and find that the reservoir’s coherence impacts the cycle from two aspects: one is the modification of the system’s steady-state populations or temperatures, and the other is the direct contributions to the heat in the interaction between the system and reservoirs. We then explore the scenario where the working substance is two identical qubits, and the reservoirs are common to them. We show that the degenerate coherence of the system in the steady state can enhance the performances of the cycle as different machines. Additionally, the energetic coherence of the reservoir modifies the functions of the cycle still through the energetic coherence of the system rather than their degenerate coherence.
... In recent years, exploring the connection between quantum effects and energy and understanding the physical mechanisms of quantum effects in quantum systems have received extensive attention. Researchers have extensively explored the thermodynamic characteristics of quantum effects based on different quantum system models, such as quantum battery [1][2][3][4], quantum engine [5][6][7][8], and quantum thermal manager [9][10]. However, we still lack a comprehensive and in-depth understanding of the relationship between quantum effects and energy, as well as the conversion mechanisms in quantum devices, which are worth further investigation. ...
Studying the relationship between quantum coherence and energy is an intriguing and vital subject in quantum thermodynamics. Quantum engine provides an excellent platform to emphasize it. By constructing a bipartite entanglement engine (BEE) model consisting of a single qubit as the target qubit and a two-qubit as the ancilla, we have investigated the influence of quantum coherence of ancilla on work extraction of BEE at length, and analytically calculated the extractable work of BEE for the ancilla with quantum coherence (QC). We found that the extractable work of BEE is not only dependent on coherence magnitude but also related to the coherence phase of ancilla. Moreover, under certain coherent parameters, the QC can boost the work extraction from BEE. The study reveals the role of QC acting as “fuel” of engine well which deepens the understanding of the energetic effect of QC.
... [11,12] For example, using the quantum coherence and squeeze, the Carnot limit can be broken, [13,14] and the reversal heat flow against the direction of negative gradient of temperature can occur. [15][16][17][18] In this context, two attractive questions have emerged. How does a quantum system implement the energy storage effectively for the later use by the other system (or load)? ...
An open quantum battery (QB) model of a single qubit system charging in a coherent auxiliary bath (CAB) consisting of a series of independent coherent ancillae is considered. According to the collision charging protocol we derive a quantum master equation and obtain the analytical solution of QB in a steady state. We find that the full charging capacity (or the maximal extractable work (MEW)) of QB, in the weak QB-ancilla coupling limit, is positively correlated with the coherence magnitude of ancilla. Combining with the numerical simulations we compare with the charging properties of QB at finite coupling strength, such as the MEW, average charging power and the charging efficiency, when considering the bath to be a thermal auxiliary bath (TAB) and a CAB, respectively. We find that when the QB with CAB, in the weak coupling regime, is in fully charging, both its capacity and charging efficiency can go beyond its classical counterpart, and they increase with the increase of coherence magnitude of ancilla. In addition, the MEW of QB in the regime of relative strong coupling and strong coherent magnitude shows the oscillatory behavior with the charging time increasing, and the first peak value can even be larger than the full charging MEW of QB. This also leads to a much larger average charging power than that of QB with TAB in a short-time charging process. These features suggest that with the help of quantum coherence of CAB it becomes feasible to switch the charging schemes between the long-time slow charging protocol with large capacity and high efficiency and the short-time rapid charging protocol with highly charging power only by adjusting the coupling strength of QB-ancilla. This work clearly demonstrates that the quantum coherence of bath can not only serve as the role of “fuel” of QB to be utilized to improve the QB’s charging performance but also provide an alternative way to integrate the different charging protocols into a single QB.
... As a matter of fact, it is of great importance to consider scenarios where one can model and manipulate non-equilibrium reservoirs. By employing them, one expects to overcome the standard thermodynamic limits as proposed in the case of quantum measurement induced [50,51], squeezed [27,[52][53][54][55][56] and coherent [17,24,[57][58][59][60][61][62][63][64] engineered reservoirs. Analysing the machine's operation in both cases of thermal and coherent reservoirs represents the most genuine way to explore novel aspects that may be induced by coherence. ...
The introduction of the quantum analogue of a Carnot engine based on a bath comprising of particles with a small amount of coherence initiated an active line of research on the harnessing of different quantum resources for the enhancement of thermal machines beyond the standard reversible limit, with an emphasis on nonthermal baths containing quantum coherence. In our work, we investigate the impact of coherence on the thermodynamic tasks of a collision model which is composed of a system interacting, in the continuous time limit, with a series of coherent ancillas of two baths at different temperatures. Our results show the advantages of utilising coherence as a resource in the operation of the machine, and allows it: (i) to exhibit unconventional behaviour such as the appearance of a hybrid refrigerator, capable of simultaneous refrigeration and generation of work, and (ii) to function as an engine or a refrigerator with efficiencies larger than the Carnot bound. Moreover, we find an effective upper bound to the efficiency of the thermal machine operating as an engine in the presence of a coherent reservoir.
... The goal is to study the effect of interaction between the system and a hierarchically structured environment (HSE), on the steady state heat flux. Collision models have proven to be effective in the thermodynamic analysis of a network of qubits between two thermal baths [55], a qubit coupled to a structured environment [56] and a system of qubits interacting with a thermal and a coherent thermal bath [57]. Moreover, coupling with an HSE is demonstrated to have a profound effect on coherent exciton transfer [58]. ...
The high energy transfer efficiency of photosynthetic complexes has been a topic of research across many disciplines. Several attempts have been made in order to explain this energy transfer enhancement in terms of quantum mechanical resources such as energetic and vibration coherence and constructive effects of environmental noise. The developments in this line of research have inspired various biomimetic works aiming to use the underlying mechanisms in biological light harvesting complexes for the improvement of synthetic systems. In this article, we explore the effect of an auxiliary hierarchically structured environment interacting with a system on the steady-state heat transport across the system. The cold and hot baths are modeled by a series of identically prepared qubits in their respective thermal states, and we use a collision model to simulate the open quantum dynamics of the system. We investigate the effects of system-environment, inter-environment couplings and coherence of the structured environment on the steady state heat flux and find that such a coupling enhances the energy transfer. Our calculations reveal that there exists a non-monotonic and non-trivial relationship between the steady-state heat flux and the mentioned parameters.
... As a matter of fact, it is of great importance to consider scenarios where one can model and manipulate non-equilibrium reservoirs. By employing them, one expects to overcome the standard thermodynamic limits as proposed in the case of quantum measurement induced [49,50], squeezed [27,[51][52][53][54][55] and coherent [17,24,[56][57][58][59][60][61][62][63] engineered reservoirs. Analysing the machine's operation in both cases of thermal and coherent reservoirs represents the most genuine way to explore novel aspects that may be induced by coherence. ...
The introduction of the quantum analogue of a Carnot engine based on a bath comprising of particles with a small amount of coherence initiated an active line of research on the harnessing of different quantum resources for the enhancement of thermal machines beyond the standard reversible limit, with an emphasis on non-thermal baths containing quantum coherence. In our work, we investigate the impact of coherence on the thermodynamic tasks of a collision model which is composed of a system interacting, in the continuous time limit, with a series of coherent ancillas of two baths at different temperatures. Our results show the advantages of utilising coherence as a resource in the operation of the machine, and allows it: (i) to exhibit unconventional behavior such as the appearance of a hybrid refrigerator, capable of simultaneous refrigeration and generation of work, and (ii) to function as an engine or a refrigerator with efficiencies larger than the Carnot bound. Moreover, we find an effective upper bound to the efficiency of the thermal machine operating as an engine in the presence of a coherent reservoir.
