Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userNear-frozen high energy state in a chiral channel driven out of equilibrium
135
0
0.0
(
0
)
Added by
Stefan Georg Fischer
Publication date
2021
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
Ergodic many-body systems are expected to reach quasi-thermal equilibrium. Here we demonstrate that, surprisingly, high-energy electrons, which are injected into an interacting one-dimensional quantum Hall edge mode, stabilize at a far-from-thermalized state over a long-time scale. To detect this non-equilibrium state, one positions an energy-resolved detector downstream of the point of injection. Previous works have shown that electron distributions, which undergo short-ranged interactions, generically relax to near-thermal asymptotic states. Here, we consider screened interactions of finite range. The thus-obtained many-body state comprises fast-decaying transient components, followed by a nearly frozen distribution with a peak near the injection energy.
rate research
Read More
The archetypal two-impurity Kondo problem in a serially-coupled double quantum dot is investigated in the presence of a thermal bias $theta$. The slave-boson formulation is employed to obtain the nonlinear thermal and thermoelectrical responses. When the Kondo correlations prevail over the antiferromagnetic coupling $J$ between dot spins we demonstrate that the setup shows negative differential thermal conductance regions behaving as a thermal diode. Besides, we report a sign reversal of the thermoelectric current $I(theta)$ controlled by $t/Gamma$ ($t$ and $Gamma$ denote the interdot tunnel and reservoir-dot tunnel couplings, respectively) and $theta$. All these features are attributed to the fact that at large $theta$, both $Q(theta)$ (heat current) and $I(theta)$ are suppressed regardless the value of $t/Gamma$ because the double dot decouples at high thermal biases. Eventually, and for a finite $J$, we investigate how the Kondo-to-antiferromagnetic crossover is altered by $theta$.
We study the non-equilibrium regime of the Kondo effect in a quantum dot laterally coupled to a narrow wire. We observe a split Kondo resonance when a finite bias voltage is imposed across the wire. The splitting is attributed to the creation of a double-step Fermi distribution function in the wire. Kondo correlations are strongly suppressed when the voltage across the wire exceeds the Kondo temperature. A perpendicular magnetic field enables us to selectively control the coupling between the dot and the two Fermi seas in the wire. Already at fields of order 0.1 T only the Kondo resonance associated with the strongly coupled reservoir survives.
In chiral magnets a magnetic helix forms where the magnetization winds around a propagation vector $mathbf{q}$. We show theoretically that a magnetic field $mathbf{B}_{perp}(t) perp mathbf{q}$, which is spatially homogeneous but oscillating in time, induces a net rotation of the texture around $mathbf{q}$. This rotation is reminiscent of the motion of an Archimedean screw and is equivalent to a translation with velocity $v_{text{screw}}$ parallel to $mathbf{q}$. Due to the coupling to a Goldstone mode, this non-linear effect arises for arbitrarily weak $mathbf{B}_{perp}(t) $ with $v_{text{screw}} propto |mathbf{B}_{perp}|^2$ as long as pinning by disorder is absent. The effect is resonantly enhanced when internal modes of the helix are excited and the sign of $v_{text{screw}}$ can be controlled either by changing the frequency or the polarization of $mathbf{B}_{perp}(t)$. The Archimedean screw can be used to transport spin and charge and thus the screwing motion is predicted to induce a voltage parallel to $mathbf{q}$. Using a combination of numerics and Floquet spin wave theory, we show that the helix becomes unstable upon increasing $mathbf{B}_{perp}$ forming a `time quasicrystal which oscillates in space and time for moderately strong drive.
Laser trapped nanoparticles have been recently used as model systems to study fundamental relations holding far from equilibrium. Here we study, both experimentally and theoretically, a nanoscale silica sphere levitated by a laser in a low density gas. The center of mass motion of the particle is subjected, at the same time, to feedback cooling and a parametric modulation driving the system into a non-equilibrium steady state. Based on the Langevin equation of motion of the particle, we derive an analytical expression for the energy distribution of this steady state showing that the average and variance of the energy distribution can be controlled separately by appropriate choice of the friction, cooling and modulation parameters. Energy distributions determined in computer simulations and measured in a laboratory experiment agree well with the analytical predictions. We analyse the particle motion also in terms of the quadratures and find thermal squeezing depending on the degree of detuning.
One of the hallmarks of bulk topology is the existence of robust boundary localized states. For instance, a conventional $d$ dimensional topological system hosts $d{-}1$ dimensional surface modes, which are protected by non-spatial symmetries. Recently, this idea has been extended to higher order topological phases with boundary modes that are localized in lower dimensions such as in the corners or in one dimensional hinges of the system. In this work, we demonstrate that a higher order topological phase can be engineered in a nonequilibrium state when the time-independent model does not possess any symmetry protected topological states. The higher order topology is protected by an emerging chiral symmetry, which is generated through the Floquet driving. Using both the exact numerical method and an effective high-frequency Hamiltonian obtained from the Brillouin-Wigner perturbation theory, we verify the emerging topological phase on a $pi$-flux square lattice. We show that the localized corner modes in our model are robust against a chiral symmetry preserving perturbation and can be classified as `extrinsic higher order topological phase. Finally, we identify a two dimensional topological invariant from the winding number of the corresponding sublattice symmetric one dimensional model. The latter model belongs to class AIII of ten-fold symmetry classification of topological matter.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
