1,721,619 research outputs found
Progresses on topological phenomena, time-driven phase transitions, and unconventional superconductivity
No full textIn this perspective we discuss three emerging fields of condensed matter physics which in recent years have attracted considerable attention. In particular, we consider the recent challenging topics on time-dependent phase transitions, topological phenomena, and unconventional superconductivity, with the aim to foster the community towards new applications and technological advancements. As for the time-dependent phase transitions, in recent years the experiments have shown light-induced phase transitions and new fields of application are emerging, including material design. Regarding topological materials, new challenges have arisen to detect the Majorana origin of quantized conductance in superconducting hybrid structures, as well as the effect of interaction on edge channels. Finally, concerning superconductivity, non-conventional pairing and correlation effects dominate the physics of a vast class of two-dimensional materials and novel devices were recently conceived. This work offers a comprehensive overview on these topics for promoting new ideas in these fertile fields of research
Non-Hermitian topological phases in an extended Kitaev model
No full textIn this work we address the study of topological phase protection of open quantum systems. Using the self-energy formalism, we investigate the paradigmatic case of an extended Kitaev model. The results show how the topological order can be affected by coupling the system to two external leads, giving rise to Non-Hermitian topological phases. Our results could be useful in spectroscopic measurements made on nanowire-based mesoscopic devices
Thouless pumping and topology
Full text linkPhysicists and engineers from all around the world are constantly thinking of ways to improve the performance of conventional electronic devices by reducing the dissipated energy and to this aim recently is working its way employing quantum technologies. In a conductor a direct current is usually associated with a dissipative flow of electrons in response to an applied bias voltage. In quantum systems, however, a dissipationless transport can be induced via adiabatic cyclic variation of the system parameters in the absence of any external bias. An example is the quantum pump, or Thouless pump, the quantum version of the famous Archimede’s screw in which water from a low-level is pushed up the tube by the slow and periodic rotation of the helicoid. The quantum device is obtained slowly time periodic potential. Interestingly, the charge pumped after a period is quantized and is connected to a bulk property of the system, the so called topological invariant, i.e. a property of a geometric shape that does not change when the shape is stretched or distorted and thus is robust to external perturbations.
The exciting developments in the exploitation of quantum pumps have been reported in an article of the prestigious journal Nature Reviews Physics involving the Department of Physics at University of Salerno, where a research on quantum devices is coordinated by Prof. Roberta Citro, and the Quantum Optics group at Ludwig Maximilian University of Munich, led by Prof. Monika Aidelsburger. The article describes in details various quantum pumps, arguing how they produce a lot less heat than conventional electric currents generators, making them promising candidates for future electronic devices with significantly reduced power consumption.
Quantum pumping has received much attention in mesoscopic electronic systems, mainly owing to its potential of reducing the dissipation of energy as wasteful heat, for defining a better current standard for metrological purpose or even being used for quantum computing. Recent experimental realizations of Thouless pumps have been observed in photonics, magneto-mechanical and electro-mechanical systems and other examples cover the fields of spintronics with implications in the efficiency of data storage and transfer
The position paper of the Task Force on Takotsubo syndrome of the European Society of Cardiology: The novelty and the contribution of Italian research
No full textCronobiologia e cardiomiopatia Tako-Tsubo
No full textLe recenti acquisizioni in tema di variabilità temporale della cardiomiopatia Tako-tsubo vengono discusse, con riferimento al recente documento di consenso sulla TTC
Topological phase diagram of coupled spinless p-wave superconductors
No full textWe investigate the topological properties of a ladder given by two one dimensional p-wave superconductors coupled together site to site by transversal hopping t. For small t, we also derive an effective model whose simpler form is feasible to implement some braiding procedures proposed in the literature
Effects of geometric frustration in Kitaev chains
Full text linkWe study the topological phase transitions of a Kitaev chain frustrated by the addition of a single long-range hopping. In order to study the topological properties of the resulting legged-ring geometry (Kitaev tie model), we generalize the transfer matrix approach through which the emergence of Majorana edge modes is analyzed. We find that geometric frustration gives rise to a topological phase diagram in which non-trivial phases alternate with trivial ones at varying the range of the hopping and the chemical potential. Robustness to disorder of non-trivial phases is also proven. Moreover, geometric frustration effects persist when translational invariance is restored by considering a multiple-tie system. These findings shed light on an entire class of experimentally realizable topological systems with long-range couplings
Effective electron-phonon coupling in the Hubbard-Holstein model in presence of strong correlations and density fluctuations
No full textThe position statement from the Taskforce on Takotsubo Syndrome of the European Society of Cardiology: new insights and the Italian research contribution
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