اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدPossible experimental manifestations of the many-body localization
35
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Recently, it was predicted that if all one-electron states in a non-interacting disordered system are localized, the interaction between electrons in the absence of coupling to phonons leads to a finite-temperature metal-insulator trnasition. Here we show that even in the presence of a weak coupling to phonons the transition manifests itself (i) in the nonlinear conduction, leading to a bistable $I$-$V$ curve, (ii) by a dramatic enhancement of the nonequilibrium current noise near the transition.
قيم البحث
اقرأ أيضاً
We review recent progress in the study of transport properties of interacting electrons subject to a disordered potential which is strong enough to localize all single-particle states. This review may also serve as a guide to the recent paper by the
authors [Annals of Physics (2006), in press]. Here we skip most of the technical details and make an attempt to discuss the physical grounds of the final-temperature metal-insulator transition described in the above-mentioned paper.
As strength of disorder enhances beyond a threshold value in many-body systems, a fundamental transformation happens through which the entire spectrum localizes, a phenomenon known as many-body localization. This has profound implications as it break
s down fundamental principles of statistical mechanics, such as thermalization and ergodicity. Due to the complexity of the problem, the investigation of the many-body localization transition has remained a big challenge. The experimental exploration of the transition point is even more challenging as most of the proposed quantities for studying such effect are practically infeasible. Here, we experimentally implement a scalable protocol for detecting the many-body localization transition point, using the dynamics of a $N=12$ superconducting qubit array. We show that the sensitivity of the dynamics to random samples becomes maximum at the transition point which leaves its fingerprints in all spatial scales. By exploiting three quantities, each with different spatial resolution, we identify the transition point with excellent match between simulation and experiment. In addition, one can detect the evidence of mobility edge through slight variation of the transition point as the initial state varies. The protocol is easily scalable and can be performed across various physical platforms.
We show that, in a many-body system, all particles can be strongly confined to the initially occupied sites for a time that scales as a high power of the ratio of the bandwidth of site energies to the hopping amplitude. Such time-domain formulation i
s complementary to the formulation of the many-body localization of all stationary states with a large localization length. The long localization lifetime is achieved by constructing a periodic sequence of site energies with a large period in a one-dimensional chain. The scaling of the localization lifetime is independent of the number of particles for a broad range of the coupling strength. The analytical results are confirmed by numerical calculations.
We investigate the occurrence of the phenomenon of many-body localization (MBL) on a D-Wave 2000Q programmable quantum annealer. We study a spin-1/2 transverse-field Ising model defined on a Chimera connectivity graph, with random exchange interactio
ns and random longitudinal fields. On this system we experimentally observe a transition from an ergodic phase to an MBL phase. We first theoretically show that the MBL transition is induced by a critical disorder strength for individual energy eigenstates in a Chimera cell, which follows from the analysis of the mean half-system block entanglement, as measured by the von Neumann entropy. We show the existence of an area law for the block entanglement over energy eigenstates for the MBL phase, which stands in contrast with an extensive volume scaling in the ergodic phase. The identification of the MBL critical point is performed via the measurement of the maximum variance of the mean block entanglement over the disorder ensemble as a function of the disorder strength. Our results for the energy density phase diagram also show the existence of a many-body mobility edge in the energy spectrum. The time-independent disordered Ising Hamiltonian is then experimentally realized by applying the reverse annealing technique allied with a pause-quench protocol on the D-Wave device. We then characterize the MBL critical point through magnetization measurements at the end of the annealing dynamics, obtaining results compatible with our theoretical predictions for the MBL transition.
The celebrated Dyson singularity signals the relative delocalization of single-particle wave functions at the zero-energy symmetry point of disordered systems with a chiral symmetry. Here we show that analogous zero modes in interacting quantum syste
ms can fully localize at sufficiently large disorder, but do so less strongly than nonzero modes, as signifed by their real-space and Fock-space localization characteristics. We demonstrate this effect in a spin-1 Ising chain, which naturally provides a chiral symmetry in an odd-dimensional Hilbert space, thereby guaranteeing the existence of a many-body zero mode at all disorder strengths. In the localized phase, the bipartite entanglement entropy of the zero mode follows an area law, but is enhanced by a system-size-independent factor of order unity when compared to the nonzero modes. Analytically, this feature can be attributed to a specific zero-mode hybridization pattern on neighboring spins. The zero mode also displays a symmetry-induced even-odd and spin-orientation fragmentation of excitations, characterized by real-space spin correlation functions, which generalizes the sublattice polarization of topological zero modes in noninteracting systems, and holds at any disorder strength.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
