6,809 research outputs found
Tenfold way and many-body zero modes in the Sachdev-Ye-Kitaev model
The Sachdev-Ye-Kitaev (SYK) model, in its simplest form, describes k Majorana fermions with random all-to-all four-body interactions. We consider the SYK model in the framework of a many-body Altland-Zirnbauer classification that sees the system as belonging to one of eight (real) symmetry classes depending on the value of k mod 8. We show that, depending on the symmetry class, the system may support exact many-body zero modes with the symmetries also dictating whether these may have a nonzero contribution to Majorana fermions, i.e., single-particle weight. These zero modes appear in all but two of the symmetry classes. When present, they leave clear signatures in physical observables that go beyond the threefold (Wigner-Dyson) possibilities for level spacing statistics studied earlier. Signatures we discover include a zero-energy peak or hole in the single-particle spectral function, depending on whether symmetries allow or forbid zero modes to have single-particle weight. The zero modes are also shown to influence the many-body dynamics, where signatures include a nonzero long-time limit for the out-of-time-order correlation function. Furthermore, we show that the extension of the four-body SYK model by quadratic terms can be interpreted as realizing the remaining two complex symmetry classes; we thus demonstrate how the entire tenfold Altland-Zirnbauer classification may emerge in the SYK model
Pertanggungjawaban Pidana Wisatawan yang Merusak Kelestarian Lingkungan Wisata
The aim of this study is to observe the enforcement of law and the criminal responsibility of tourists for tourism. Type of juridical normative study using juridical normative and juridical empirical methods. That the law is enforced when there is a violation of it, since the person committing the violation should be held accountable. The individual who can be held responsible is one who is mentally sane. The weight of the penalty is based on the elements of the violatio
Domain wall in a chiral p-wave superconductor: a pathway for electrical current
Superconductors with p+ip pairing symmetry are characterized by chiral edge
states, but these are difficult to detect in equilibrium since the resulting
magnetic field is screened by the Meissner effect. Nonequilibrium detection is
hindered by the fact that the edge excitations are unpaired Majorana fermions,
which cannot transport charge near the Fermi level. Here we show that the
boundary between p_x+ip_y and p_x-ip_y domains forms a one-way channel for
electrical charge. We derive a product rule for the domain wall conductance,
which allows to cancel the effect of a tunnel barrier between metal electrodes
and superconductor and provides a unique signature of topological
superconductors in the chiral p-wave symmetry class.Comment: 6 pages, 3 figure
Multi-channel Kondo impurity dynamics in a Majorana device
We study the multi-channel Kondo impurity dynamics realized in a mesoscopic
superconducting island connected to metallic leads. The effective 'impurity
spin' is non-locally realized by Majorana bound states and strongly coupled to
lead electrons by non-Fermi liquid correlations. We explore the spin dynamics
and its observable ramifications near the low-temperature fixed point. The
topological protection of the system raises the perspective to observe
multi-channel Kondo impurity dynamics in experimentally realistic environments.Comment: 4.6 pages; published versio
Fast Monte Carlo simulations and singularities in the probability distributions of non-equilibrium systems
A numerical technique is introduced that reduces exponentially the time
required for Monte Carlo simulations of non-equilibrium systems. Results for
the quasi-stationary probability distribution in two model systems are compared
with the asymptotically exact theory in the limit of extremely small noise
intensity. Singularities of the non-equilibrium distributions are revealed by
the simulations.Comment: 4 pages, 4 figure
Novel integrated tunable laser using filtered feedback for simple and very fast tuning
We present a novel integrated tunable laser based on filtered feedback, which combines a simple tuning method with ns switching speed
Random-matrix theory of thermal conduction in superconducting quantum dots.
Theoretical Physic
Integrated filtered-feedback tunable laser with enhanced control of feedback phase
Recently we presented a novel discretely tunable laser that consists of a Fabry-Perot laser which was forced to operate in single-mode condition by applying on-chip filtered feedback. The laser switches extremely fast (3 ns) and requires simple on/off control currents to switch the wavelength. In these first devices it was not possible to control the phase of the feedback light independently from the feedback intensity. In was solved by adding an extra electrode allowing us to control the phase separately. In this paper we present the new device and study the effect of the control ofthefeedbackphase in order to improve the performance ofthe original tunable laser concept
Fast integrated tunable laser using filtered feedback
A novel integrated tunable laser is presented which combines a simple tuning method with ns switching speed. The Photonic Integrated Circuit consists of a Fabry-Perot laser with deeply-etched DBR mirrors. The Fabry-Perot modes can be selected independently using an Arrayed Waveguide Grating and then re-injected into the laser cavity, forcing single mode operation at the wavelength of that mode. 4ns switching time as well as 15 dB SMSR is demonstrated on the prototype device
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