In this paper, we analyze dissipative diamagnetism, arising due to dissipative cyclotron motion in two dimensions, in the light of the quantum counterpart of energy equipartition theorem. We consider ...a charged quantum particle moving in a harmonic well, in the presence of a uniform magnetic field, and coupled to a quantum heat bath which is taken to be composed of an infinite number of independent quantum oscillators. The quantum counterpart of energy equipartition theorem tells us that it is possible to express the mean kinetic energy of the dissipative oscillator as a two-fold average, where, the first averaging is performed over the Gibbs canonical state of the heat bath while the second one is governed by a probability distribution function Pk(ω). We analyze this result further, and also demonstrate its consistency in the weak-coupling limit. Following this, we compute the equilibrium magnetic moment of the system, and reveal an interesting connection with the quantum counterpart of energy equipartition theorem. The expressions for kinetic energy and magnetic moment are reformulated in the context of superstatistics, i.e. the superposition of two statistics. A comparative study of the present results with those obtained from the more traditional Gibbs approach is performed and a perfect agreement is obtained.
Effective field theory of dissipative fluids Crossley, Michael; Glorioso, Paolo; Liu, Hong
The journal of high energy physics,
09/2017, Letnik:
2017, Številka:
9
Journal Article
Recenzirano
Odprti dostop
A
bstract
We develop an effective field theory for dissipative fluids which governs the dynamics of long-lived gapless modes associated with conserved quantities. The resulting theory gives a path ...integral formulation of fluctuating hydrodynamics which systematically incorporates nonlinear interactions of noises. The dynamical variables are mappings between a “fluid spacetime” and the physical spacetime and an essential aspect of our formulation is to identify the appropriate symmetries in the fluid spacetime. The theory applies to nonlinear disturbances around a general density matrix. For a thermal density matrix, we require an additional
Z
2
symmetry, to which we refer as the local KMS condition. This leads to the standard constraints of hydrodynamics, as well as a nonlinear generalization of the Onsager relations. It also leads to an emergent supersymmetry in the classical statistical regime, and a higher derivative deformation of supersymmetry in the full quantum regime.
Control of multistability Pisarchik, Alexander N.; Feudel, Ulrike
Physics reports,
07/2014, Letnik:
540, Številka:
4
Journal Article
Recenzirano
Multistability or coexistence of different attractors for a given set of parameters is one of the most exciting phenomena in dynamical systems. It can be found in different areas of science, such as ...physics, chemistry, biology, economy, and in nature. The final state of a multistable system depends crucially on the initial conditions. From the viewpoint of applications, there are two major issues related to the emergence of multistability. On one hand, this phenomenon often can create inconvenience, as for instance, in the design of a commercial device with specific characteristics, where multistability needs to be avoided or the desired state has to be stabilized against a noisy environment, and on the other hand, the coexistence of different stable states offers a great flexibility in the system performance without major parameter changes, that can be used with the right control strategies to induce a definite switching between different coexisting states. These two examples alone illustrate the importance of multistability control in applied nonlinear science. For the last decade a lot of research has been devoted to the development of control techniques of multistable systems. These methods cover several strategies, going from feedback control methods to nonfeedback, such as periodic or stochastic perturbations capable of changing the coexisting states stability and driving the system from multistability to monostability. We review the most representative control strategies, discuss their theoretical background and experimental realization.
The Dicke model-a paradigmatic example of superradiance in quantum optics-describes an ensemble of atoms which are collectively coupled to a leaky cavity mode. As a result of the cooperative nature ...of these interactions, the system's dynamics is captured by the behavior of a single mean-field, collective spin. In this mean-field limit, it has recently been shown that the interplay between photon losses and periodic driving of light-matter coupling can lead to time-crystalline-like behavior of the collective spin (Gong et al 2018 Phys. Rev. Lett. 120 040404). In this work, we investigate whether such a Dicke time crystal (TC) is stable to perturbations that explicitly break the mean-field solvability of the conventional Dicke model. In particular, we consider the addition of short-range interactions between the atoms which breaks the collective coupling and leads to complex many-body dynamics. In this context, the interplay between periodic driving, dissipation and interactions yields a rich set of dynamical responses, including long-lived and metastable Dicke-TCs, where losses can cool down the many-body heating resulting from the continuous pump of energy from the periodic drive. Specifically, when the additional short-range interactions are ferromagnetic, we observe time crystalline behavior at non-perturbative values of the coupling strength, suggesting the possible existence of stable dynamical order in a driven-dissipative quantum many-body system. These findings illustrate the rich nature of novel dynamical responses with many-body character in quantum optics platforms.
The AC Josephson effect manifests itself in the form of “Shapiro steps” of quantized voltage in Josephson junctions subject to radiofrequency (RF) radiation. This effect presents an early example of ...a driven–dissipative quantum phenomenon and is presently utilized in primary voltage standards. Shapiro steps have also become one of the standard tools to probe junctions made in a variety of novel materials. Here we study Shapiro steps in a widely tunable graphene-based Josephson junction in which the high-frequency dynamics is determined by the on-chip environment. We investigate the variety of patterns that can be obtained in this well-understood system depending on the carrier density, temperature, RF frequency, and magnetic field. Although the patterns of Shapiro steps can change drastically when just one parameter is varied, the overall trends can be understood and the behaviors straightforwardly simulated, showing some key differences from the conventional RCSJ model. The resulting understanding may help interpret similar measurements in more complex materials.
Contact Hamiltonian mechanics Bravetti, Alessandro; Cruz, Hans; Tapias, Diego
Annals of physics,
01/2017, Letnik:
376
Journal Article
Recenzirano
Odprti dostop
In this work we introduce contact Hamiltonian mechanics, an extension of symplectic Hamiltonian mechanics, and show that it is a natural candidate for a geometric description of non-dissipative and ...dissipative systems. For this purpose we review in detail the major features of standard symplectic Hamiltonian dynamics and show that all of them can be generalized to the contact case.
The way chemical transformations are described by models based on microscopic reversibility does not take into account the irreversibility of natural processes, and therefore, in complex chemical ...networks working in open systems, misunderstandings may arise about the origin and causes of the stability of non‐equilibrium stationary states, and general constraints on evolution in systems that are far from equilibrium. For more details, see the Concept by J. M. Ribó and D. Hochberg on page 13098 ff.
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