Energetic fluctuations in an open quantum process

Relations similar to work and exchange fluctuations have been recently derived for open systems dynamically evolving in the presence of an ancilla. Extending these relations and constructing a non-equilibrium Helmholtz equation we derive a general expression for the energetic and entropic changes of an open quantum system undergoing a nontrivial evolution. The expressions depend only on the state of the system and the dynamical map generating the evolution. Furthermore our formalism makes no assumption on either the nature or dimension of the ancilla. Our results are expected to find application in understanding the energetics of complex quantum systems undergoing open dynamics.Comment: 5 pages and 3 figure

Protecting Information Privacy

This report for the Equality and Human Rights Commission (the Commission) examines the threats to information privacy that have emerged in recent years, focusing on the activities of the state. It argues that current privacy laws and regulation do not adequately uphold human rights, and that fundamental reform is required. It identifies two principal areas of concern: the state’s handling of personal data, and the use of surveillance by public bodies. The central finding of this report is that the existing approach to the protection of information privacy in the UK is fundamentally flawed, and that there is a pressing need for widespread legislative reform in order to ensure that the rights contained in Article 8 are respected. The report argues for the establishment of a number of key ‘privacy principles’ that can be used to guide future legal reforms and the development of sector-specific regulation. The right to privacy is at risk of being eroded by the growing demand for information by government and the private sector. Unless we start to reform the law and build a regulatory system capable of protecting information privacy, we may soon find that it is a thing of the past

Prion degradation pathways: Potential for therapeutic intervention

Prion diseases are fatal neurodegenerative disorders. Pathology is closely linked to the misfolding of native cellular PrP(C) into the disease-associated form PrP(Sc) that accumulates in the brain as disease progresses. Although treatments have yet to be developed, strategies aimed at stimulating the degradation of PrP(Sc) have shown efficacy in experimental models of prion disease. Here, we describe the cellular pathways that mediate PrP(Sc) degradation and review possible targets for therapeutic intervention. This article is part of a Special Issue entitled 'Neuronal Protein'

Total correlations of the diagonal ensemble as a generic indicator for ergodicity breaking in quantum systems

The diagonal ensemble is the infinite time average of a quantum state following unitary dynamics. In analogy to the time average of a classical phase space dynamics, it is intimately related to the ergodic properties of the quantum system giving information on the spreading of the initial state in the eigenstates of the Hamiltonian. In this work we apply a concept from quantum information, known as total correlations, to the diagonal ensemble. Forming an upper-bound on the multipartite entanglement, it quantifies the combination of both classical and quantum correlations in a mixed state. We generalize the total correlations of the diagonal ensemble to more general $\alpha$-Renyi entropies and focus on the the cases $\alpha=1$ and $\alpha=2$ with further numerical extensions in mind. Here we show that the total correlations of the diagonal ensemble is a generic indicator of ergodicity breaking, displaying a sub-extensive behaviour when the system is ergodic. We demonstrate this by investigating its scaling in a range of spin chain models focusing not only on the cases of integrability breaking but also emphasize its role in understanding the transition from an ergodic to a many body localized phase in systems with disorder or quasi-periodicity.Comment: v3: several minor improvement

A non-equilibrium quantum Landauer principle

Using the operational framework of completely positive, trace preserving operations and thermodynamic fluctuation relations, we derive a lower bound for the heat exchange in a Landauer erasure process on a quantum system. Our bound comes from a non-phenomenological derivation of the Landauer principle which holds for generic non-equilibrium dynamics. Furthermore the bound depends on the non-unitality of dynamics, giving it a physical significance that differs from other derivations. We apply our framework to the model of a spin-1/2 system coupled to an interacting spin chain at finite temperature.Comment: 4 pages, 2 figures, RevTeX4-1; Accepted for publication in Phys. Rev. Let

International Differences in the Size and Roles of Corporate Headquarters: An Empirical Examination

This paper examines differences in the size and roles of corporate headquarters around the world. Based on a survey of over 600 multibusiness corporations in seven countries (France, Germany, Holland, UK, Japan, US, and Chile) the paper describes the differences among countries, and then applies a model of the factors determining the size of corporate headquarters (Young, Collis, and Goold, 2003) to systematically examine those differences. The data shows that there are significant differences among countries in the size and role of corporate headquarters, and strongly suggests the existence of a developing country model, a European model, a US model, and a Japanese model of corporate headquarters. Contrary to popular expectations, corporate headquarters in the US are about twice the size of European counterparts. Headquarters there exert a higher level of functional influence and have larger staffs in certain key areas, such as IT and R&D. US managers are generally more satisfied than their European counterparts with their larger more powerful headquarters which suggests that, at least in the US context, large corporate headquarters can create value. Japanese headquarters, as might have been expected, are substantially larger than elsewhere – a factor of four times larger than in Europe. However, those headquarters are becoming smaller because of dissatisfaction with their performance. It is clear that having headquarters the size of the Japanese firms in the survey is not conducive to value creation. More specifically, the evidence cannot refute a hypothesis that the slope of the relationship between firm size and the size of corporate headquarters is the same across all countries, but that there are significant differences in the intercept for Chile, the US, Japan, and the European countries. What the data indicates is that at a firm employing 20,000, a European corporate headquarters would on average employ 124 individuals, a US headquarters would have 255 employees, and Japan 467 employees. The paper also examines differences between countries in the extent to which they perform the two key corporate tasks of control and coordination. The US and Chile chose to be somewhat more interventionist in the traditional tools and processes used to monitor and control business units – setting strategy, budgets, and administering capital budgets. However, there was a significant difference in the degree of influence in operational affairs between countries. The US and Japan exerted far more influence than the other countries over every activity from IT and purchasing, to marketing, R&D and HR issues. The US was also found to have significantly larger legal, tax, and treasury functions than the common European model, perhaps reflecting a more legalistic institutional structure. Japan also has significantly larger tax, treasury, and corporate management functions, but overall was not that much larger than the common European model. While the causes of these observed differences cannot be directly determined from the research, suggestions are made that the institutional infrastructure, the size and homogeneity of the domestic market, and cultural factors within countries are important underlying drivers.

An eccentrically perturbed Tonks-Girardeau gas

We investigate the static and dynamic properties of a Tonks-Girardeau gas in a harmonic trap with an eccentric $\delta$-perturbation of variable strength. For this we first find the analytic eigensolution of the single particle problem and use this solution to calculate the spatial density and energy profiles of the many particle gas as a function of the strength and position of the perturbation. We find that the crystal nature of the Tonks state is reflected in both the lowest occupation number and momentum distribution of the gas. As a novel application of our model, we study the time evolution of the the spatial density after a sudden removal of the perturbation. The dynamics exhibits collapses and revivals of the original density distribution which occur in units of the trap frequency. This is reminiscent of the Talbot effect from classical optics.Comment: Comments and suggestions are welcom