4,147 research outputs found
Orbital calculations and trapped radiation mapping
Flux and energy spectra code for orbital calculations and trapped radiation mappin
Information propagation through quantum chains with fluctuating disorder
We investigate the propagation of information through one-dimensional quantum
chains in fluctuating external fields. We find that information propagation is
suppressed, but in a quite different way compared to the situation with static
disorder. We study two settings: (i) a general model where an unobservable
fluctuating field acts as a source of decoherence; (ii) the XX model with both
observable and unobservable fluctuating fields. In the first setting we
establish a noise threshold below which information can propagate ballistically
and above which information is localised. In the second setting we find
localisation for all levels of unobservable noise, whilst an observable field
can yield diffusive propagation of information.Comment: 5 pages, 2 figure
Recommended from our members
When users control the algorithms: Values expressed in practices on the twitter platform
Recent interest in ethical AI has brought a slew of values, including fairness, into conversations about technology design. Research in the area of algorithmic fairness tends to be rooted in questions of distribution that can be subject to precise formalism and technical implementation. We seek to expand this conversation to include the experiences of people subject to algorithmic classification and decision-making. By examining tweets about the “Twitter algorithm” we consider the wide range of concerns and desires Twitter users express. We find a concern with fairness (narrowly construed) is present, particularly in the ways users complain that the platform enacts a political bias against conservatives. However, we find another important category of concern, evident in attempts to exert control over the algorithm. Twitter users who seek control do so for a variety of reasons, many well justified. We argue for the need for better and clearer definitions of what constitutes legitimate and illegitimate control over algorithmic processes and to consider support for users who wish to enact their own collective choices
A preliminary report on energetic space radiation and dose rate analysis
Energetic space radiation and dose rate analysi
Bounds on Information Propagation in Disordered Quantum Spin Chains
We investigate the propagation of information through the disordered XY
model. We find, with a probability that increases with the size of the system,
that all correlations, both classical and quantum, are suppressed outside of an
effective lightcone whose radius grows at most polylogarithmically with |t|.Comment: 4 pages, pdflatex, 1 pdf figure. Corrected the bound for the
localised propagator and quantified the probability it bound occur
Charged particle radiation environment for the LST
Preliminary charged particle dose rates are presented for the LST orbit. The trapped proton component appears to dominate the total dose for the expected shielding available. Typical dose rates should range from 400 to 800 millirads/day
Resource Bound Guarantees via Programming Languages
We present a programming language in which every well-typed program halts in time polynomial with respect to its input and, more importantly, in which upper bounds on resource requirements can be inferred with certainty. Ensuring that software meets its resource constraints is important in a number of domains, most prominently in hard real-time systems and safety critical systems where failing to meet its time constraints can result in catastrophic failure. The use of test- ing in ensuring resource constraints is of limited use since the testing of every input or environment is impossible in general. Static analysis, whether via the compiler or com- plementary programming tool, can generate proofs of correctness with certainty at the cost that not all programs can be analysed. We describe a programming language, Pola, which provides upper bounds on resource usage for well-typed programs. Further, we describe novel features of Pola that make it more expressive than existing resource-constrained programming languages
- …