Entropy of a Quantum Oscillator coupled to a Heat Bath and implications for Quantum Thermodynamics

The free energy of a quantum oscillator in an arbitrary heat bath at a temperature T is given by a "remarkable formula" which involves only a single integral. This leads to a corresponding simple result for the entropy. The low temperature limit is examined in detail and we obtain explicit results both for the case of an Ohmic heat bath and a radiation heat bath. More general heat bath models are also examined. This enables us to determine the entropy at zero temperature in order to check the third law of thermodynamics in the quantum regimeComment: International Conference on "Frontiers of Quantum and Mesoscopic Thermodynamics

Decoherence in Nanostructures and Quantum Systems

Decoherence phenomena are pervasive in the arena of nanostructures but perhaps even more so in the study of the fundamentals of quantum mechanics and quantum computation. Since there has been little overlap between the studies in both arenas, this is an attempt to bridge the gap. Topics stressed include (a) wave packet spreading in a dissipative environment, a key element in all arenas, (b) the definition of a quantitative measure of decoherence, (c) the near zero and zero temperature limit, and (d) the key role played by initial conditions: system and environment entangled at all times so that one must use the density matrix (or Wigner distribution) for the complete system or initially decoupled system and environment so that use of a reduced density matrix or reduced Wigner distribution is feasible. Our approach utilizes generalized quantum Langevin equations and Wigner distributions

Plugging Side-Channel Leaks with Timing Information Flow Control

The cloud model's dependence on massive parallelism and resource sharing exacerbates the security challenge of timing side-channels. Timing Information Flow Control (TIFC) is a novel adaptation of IFC techniques that may offer a way to reason about, and ultimately control, the flow of sensitive information through systems via timing channels. With TIFC, objects such as files, messages, and processes carry not just content labels describing the ownership of the object's "bits," but also timing labels describing information contained in timing events affecting the object, such as process creation/termination or message reception. With two system design tools-deterministic execution and pacing queues-TIFC enables the construction of "timing-hardened" cloud infrastructure that permits statistical multiplexing, while aggregating and rate-limiting timing information leakage between hosted computations.Comment: 5 pages, 3 figure

Embedding QR codes in the Bournemouth University print collection

During the 2011/12 academic year, Library and Learning Support (LLS) at BU have been working on a project to embed QR codes within the library print collection to highlight available e-books from heavily used areas of the shelves

VXA: A Virtual Architecture for Durable Compressed Archives

Data compression algorithms change frequently, and obsolete decoders do not always run on new hardware and operating systems, threatening the long-term usability of content archived using those algorithms. Re-encoding content into new formats is cumbersome, and highly undesirable when lossy compression is involved. Processor architectures, in contrast, have remained comparatively stable over recent decades. VXA, an archival storage system designed around this observation, archives executable decoders along with the encoded content it stores. VXA decoders run in a specialized virtual machine that implements an OS-independent execution environment based on the standard x86 architecture. The VXA virtual machine strictly limits access to host system services, making decoders safe to run even if an archive contains malicious code. VXA's adoption of a "native" processor architecture instead of type-safe language technology allows reuse of existing "hand-optimized" decoders in C and assembly language, and permits decoders access to performance-enhancing architecture features such as vector processing instructions. The performance cost of VXA's virtualization is typically less than 15% compared with the same decoders running natively. The storage cost of archived decoders, typically 30-130KB each, can be amortized across many archived files sharing the same compression method.Comment: 14 pages, 7 figures, 2 table