7 research outputs found
Measuring adiabaticity in nonequilibrium quantum systems
Understanding out-of-equilibrium quantum dynamics is a critical outstanding problem, with key questions regarding characterizing adiabaticity for applications in quantum technologies. We show how the metric-space approach to quantum mechanics naturally characterizes regimes of quantum dynamics and provides an appealingly visual tool for assessing their degree of adiabaticity. Further, the dynamic trajectories of quantum systems in metric space suggest a lack of ergodicity, thus providing a better understanding of the fundamental one-to-one mapping between densities and wave functions
Many-body effects on the thermodynamics of closed quantum systems
Thermodynamics of quantum systems out-of-equilibrium is very important for
the progress of quantum technologies, however, the effects of many body
interactions and their interplay with temperature, different drives and
dynamical regimes is still largely unknown. Here we present a systematic study
of these interplays: we consider a variety of interaction (from non-interacting
to strongly correlated) and dynamical (from sudden quench to quasi-adiabatic)
regimes, and draw some general conclusions in relation to work extraction and
entropy production. As treatment of many-body interacting systems is highly
challenging, we introduce a simple approximation which includes, for the
average quantum work, many-body interactions only via the initial state, while
the dynamics is fully non-interacting. We demonstrate that this simple
approximation is surprisingly good for estimating both the average quantum work
and the related entropy variation, even when many-body correlations are
significant.Comment: 17 pages, 11 figure
ALS-linked FUS mutations confer loss and gain of function in the nucleus by promoting excessive formation of dysfunctional paraspeckles
Mutations in the FUS gene cause amyotrophic lateral sclerosis (ALS-FUS). Mutant FUS is known to confer cytoplasmic gain of function but its effects in the nucleus are less understood. FUS is an essential component of paraspeckles, subnuclear bodies assembled on a lncRNA NEAT1. Paraspeckles may play a protective role specifically in degenerating spinal motor neurons. However it is still unknown how endogenous levels of mutant FUS would affect NEAT1/paraspeckles. Using novel cell lines with the FUS gene modified by CRISPR/Cas9 and human patient fibroblasts, we found that endogenous levels of mutant FUS cause accumulation of NEAT1 isoforms and paraspeckles. However, despite only mild cytoplasmic mislocalisation of FUS, paraspeckle integrity is compromised in these cells, as confirmed by reduced interaction of mutant FUS with core paraspeckle proteins NONO and SFPQ and increased NEAT1 extractability. This results in NEAT1 localisation outside paraspeckles, especially prominent under conditions of paraspeckle-inducing stress. Consistently, paraspeckle-dependent microRNA production, a readout for functionality of paraspeckles, is impaired in cells expressing mutant FUS. In line with the cellular data, we observed paraspeckle hyper-assembly in spinal neurons of ALS-FUS patients. Therefore, despite largely preserving its nuclear localisation, mutant FUS leads to loss (dysfunctional paraspeckles) and gain (excess of free NEAT1) of function in the nucleus. Perturbed fine structure and functionality of paraspeckles accompanied by accumulation of non-paraspeckle NEAT1 may contribute to the disease severity in ALS-FUS
Metrics for Two Electron Random Potential Systems
Metrics have been used to investigate the relationship between wavefunction distances and density distances for families of specific systems. We extend this research to look at random potentials for time-dependent single-electron systems, and for ground-state two-electron systems. We find that Fourier series are a good basis for generating random potentials. These random potentials also yield quasi-linear relationships between the distances of ground-state densities and wavefunctions, providing a framework in which density functional theory can be explored