33 research outputs found
Construction of exact constants of motion and effective models for many-body localized systems
One of the defining features of many-body localization is the presence of
extensively many quasi-local conserved quantities. These constants of motion
constitute a corner-stone to an intuitive understanding of much of the
phenomenology of many-body localized systems arising from effective
Hamiltonians. They may be seen as local magnetization operators smeared out by
a quasi-local unitary. However, accurately identifying such constants of motion
remains a challenging problem. Current numerical constructions often capture
the conserved operators only approximately restricting a conclusive
understanding of many-body localization. In this work, we use methods from the
theory of quantum many-body systems out of equilibrium to establish a new
approach for finding a complete set of exact constants of motion which are in
addition guaranteed to represent Pauli- operators. By this we are able to
construct and investigate the proposed effective Hamiltonian using exact
diagonalization. Hence, our work provides an important tool expected to further
boost inquiries into the breakdown of transport due to quenched disorder.Comment: 8 pages, 8 figures, replaced with published versio
Vibrationally Resolved Decay Width of Interatomic Coulombic Decay in HeNe
We investigate the ionization of HeNe from below the He 1s3p excitation to
the He ionization threshold. We observe HeNe ions with an enhancement by
more than a factor of 60 when the He side couples resonantly to the radiation
field. These ions are an experimental proof of a two-center resonant
photoionization mechanism predicted by Najjari et al. [Phys. Rev. Lett. 105,
153002 (2010)]. Furthermore, our data provide electronic and vibrational state
resolved decay widths of interatomic Coulombic decay (ICD) in HeNe dimers. We
find that the ICD lifetime strongly increases with increasing vibrational
state.Comment: 7 pages, 5 figure
A measurement of the evolution of Interatomic Coulombic Decay in the time domain
During the last 15 years a novel decay mechanism of excited atoms has been
discovered and investigated. This so called ''Interatomic Coulombic Decay''
(ICD) involves the chemical environment of the electronically excited atom: the
excitation energy is transferred (in many cases over long distances) to a
neighbor of the initially excited particle usually ionizing that neighbor. It
turned out that ICD is a very common decay route in nature as it occurs across
van-der-Waals and hydrogen bonds. The time evolution of ICD is predicted to be
highly complex, as its efficiency strongly depends on the distance of the atoms
involved and this distance typically changes during the decay. Here we present
the first direct measurement of the temporal evolution of ICD using a novel
experimental approach.Comment: 6 pages, 4 figures, submitted to PR
Interatomic-Coulombic-decay-induced recapture of photoelectrons in helium dimers
We investigate the onset of photoionization shakeup induced interatomic
Coulombic decay (ICD) in He2 at the He+*(n = 2) threshold by detecting two He+
ions in coincidence. We find this threshold to be shifted towards higher
energies compared to the same threshold in the monomer. The shifted onset of
ion pairs created by ICD is attributed to a recapture of the threshold
photoelectron after the emission of the faster ICD electron.Comment: 5 Pages, 2 Figure