Interacting adiabatic quantum motor

Bruch, Anton; Kusminskiy, Silvia Viola; Refael, Gil; Oppen, Felix von

doi:10.1103/physrevb.97.195411

Cited by 20 publications

(21 citation statements)

References 35 publications

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“…We can also observe a significant increase of the maximum value of dissipation (around L max 22 ∼ 0.55 −1 ) with respect to the noninteracting problem (L max 22 ∼ 0.32 −1 ). An increment of the dissipation in nanomotors due to electronic interactions was also reported in [37]. This effect can be traced back to the fact that there are more ac-parameters in the interacting problem, that contribute to the pumping of charge as well as to the dissipation.…”

Section: Resultsmentioning

confidence: 67%

Enhanced performance of a quantum-dot-based nanomotor due to Coulomb interactions

Ludovico

Capone

2018

Phys. Rev. B

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We study the relation between quantum pumping of charge and the work exchanged with the driving potentials in a strongly interacting ac-driven quantum dot. We work in the large-interaction limit and in the adiabatic pumping regime, and we develop a treatment that combines the timedependent slave-boson approximation with linear response in the rate of change of the ac-potentials. We find that the time evolution of the system can be described in terms of equilibrium solutions at every time. We analyze the effect of the electronic interactions on the performance of the dot when operating as a quantum motor.The main two effects of the interactions are a shift of the resonance and an enhancement of the efficiency with respect to a non-interacting dot. This is due to the appearance of additional acparameters accounting for the interactions that increase the pumping of particles while decreasing the conductance.

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Section: Resultsmentioning

confidence: 67%

Enhanced performance of a quantum-dot-based nanomotor due to Coulomb interactions

Ludovico

Capone

2018

Phys. Rev. B

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“…In [ 49 , 50 , 51 ], the CIFs were obtained from the Floquet–Green’s function formalism. The role of Coulomb interactions was addressed through different formalisms and methods like, e.g., many-body perturbation theory based on nonequilibrium Green’s functions [ 44 ]; modeling the system as a Luttinger liquid [ 24 ]; and using a time-dependent slave-boson approximation [ 26 ]. In [ 42 ], explicit expressions for the CIFs within the Coulomb blockade regime of transport were obtained using a real-time diagrammatic approach [ 78 ], which we present in more detail in Section 7 when considering the example of Figure 1 c.…”

Section: Current-induced Forces and Langevin Equationmentioning

confidence: 99%

“…In recent years, there has been a sustained growth in the interest in different forms of nanomachines. This was boosted by seminal experiments [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ], the blooming of new theoretical proposals [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ], and the latest developments towards the understanding of the fundamental physics underlying such systems [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ]. Quantum mechanics has proven to be crucial in the description of a broad family of nanomachines, which can be put together under the generic name of “quantum motors” and “quantum pumps” [ 13 , 46 , 47 , 48 , 49 , 50 , ...…”

Section: Introductionmentioning

confidence: 99%

“…A typical problem is that when these devices are coupled to nonequilibrium sources, nonconservative current-induced forces (CIFs) appear. These CIFs come, in the first place, by assuming a type of Born–Oppenheimer approximation where the electronic and mechanical degrees of freedom can be treated separately and, secondly, by evaluating the mean value of the force operator [ 10 , 11 , 22 , 24 , 26 , 34 , 35 , 37 , 39 , 42 , 44 , 49 , 50 , 51 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 ]. Because of the delayed response of the electronic degrees of freedom to the mechanical motion, one should include the so-called nonadiabatic corrections with the CIFs.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamics and Steady State of Quantum Motors and Pumps Far from Equilibrium

Bustos-Marún

Calvo

2019

Entropy

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In this article, we briefly review dynamical and thermodynamical aspects of different forms of quantum motors and quantum pumps. We then extend previous results to provide new theoretical tools for a systematic study of those phenomena at far-from-equilibrium conditions. We mainly focus on two key topics: (1) The steady-state regime of quantum motors and pumps, paying particular attention to the role of higher-order terms in the nonadiabatic expansion of the current-induced forces.(2) The thermodynamical properties of such systems, emphasizing systematic ways of studying the relationship between different energy fluxes (charge and heat currents, and mechanical power) passing through the system when beyond-first-order expansions are required. We derive a general order-by-order scheme based on energy conservation to rationalize how every order of the expansion of one form of energy flux is connected with the others. We use this approach to give a physical interpretation of the leading terms of the expansion. Finally, we illustrate the above-discussed topics in a double quantum dot within the Coulomb-blockade regime and capacitively coupled to a mechanical rotor. We find many exciting features of this system for arbitrary nonequilibrium conditions: A definite parity of the expansion coefficients with respect to the voltage or temperature biases; negative friction coefficients; and the fact that, under fixed parameters, the device can exhibit multiple steady states where it may operate as a quantum motor or as a quantum pump depending on the initial conditions.

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“…However, the underlying physical mechanisms leading to unidirectional molecular rotation are not well understood, since they involve in general terms a delicate interplay between collective mechanical and electronic degrees of freedom. On the theoretical side, a combination of model-based approaches [28][29][30][31][32][33][34], catching the basic physics of the problem with more advanced first-principles methodologies able to provide atomistic, system-specific information is required. Some of the problems here include, e.g.…”

Section: Introductionmentioning

confidence: 99%

Current-induced rotations of molecular gears

Lin

Joachim

2019

J. Phys. Commun.

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Downsizing of devices opens the question of how to tune not only their electronic properties, but also of how to influence 'mechanical' degrees of freedom such as translational and rotational motions. Experimentally, this has been meanwhile demonstrated by manipulating individual molecules with e.g. current pulses from a Scanning Tunneling Microscope tip. Here, we propose a rotational version of the well-known Anderson-Holstein model to address the coupling between collective rotational variables and the molecular electronic system with the goal of exploring conditions for unidirectional rotation. Our approach is based on a quantum-classical description leading to effective Langevin equations for the mechanical degrees of freedom of the molecular rotor. By introducing a timedependent gate to mimic the influence of current pulses on the molecule, we show that unidirectional rotations can be achieved by fine tuning the time-dependence of the gate as well as by changing the relative position of the potential energy surfaces involved in the rotational process. idea by going beyond the linear coupling regime and, more importantly, by considering a non-harmonic, periodic potential energy surfaces associated with a collective rotational degree of freedom rather than with the linear displacement of the standard AHM. Our basic assumption is that the movement of the tip of a Scanning Tunneling Microscope (STM) can act as an effective time-dependent electrical gate for a molecule deposited on the substrate, being able to generate a current-induce rotation. The setup we are envisioning is displayed in figure 1: a single molecule adsorbed on a metallic substrate is electrically addressed by the STM tip. This gate is able to change the average occupation of the relevant electronic state coupled to the collective rotational variable (s) and it may thus trigger a (possibly) unidirectional rotation of the molecule. Specifically, we can design two PESs with a given separation of minima and choose an appropriate switching of the gate to make the molecule rotate one-way. To address this problem, we use a quantum-classical approach to the problem, by considering the rotational degrees of freedom as classical variables, whose dynamics is governed by a generalized Langevin equation, while, on the other hand, the electronic system is treated within the nonequilibrium Green function (NEGF) technique exploiting methods developed in the context of current-induced forces [39][40][41][42][43][44][45].The outline of the article is as follows: in section 2, the rotational analogy of the AHM Hamiltonian is formulated and the corresponding equation of motion and the reduced density matrix are discussed. In section 3, a simple example of a planar molecule with N-fold symmetry is considered. By performing an adiabatic expansion in the reduced density matrix, we derive an equation of motion in the adiabatic limit, which allows simplifying the problem and leading to the concept of mean torque, damping, and external-driving torque. Consequently, it e...

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Interacting adiabatic quantum motor

Cited by 20 publications

References 35 publications

Enhanced performance of a quantum-dot-based nanomotor due to Coulomb interactions

Enhanced performance of a quantum-dot-based nanomotor due to Coulomb interactions

Thermodynamics and Steady State of Quantum Motors and Pumps Far from Equilibrium

Current-induced rotations of molecular gears

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