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

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

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

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

Intent in Patent Infringement

In An Intentional Tort Theory of Patents , Professor Vishnubhakat makes two arguments. First, that liability for patent infringement should only be imposed upon defendants who intentionally make, use, or sell, patented inventions. And second, that if patent infringement includes such an intent requirement, it would no longer be a strict liability tort. This response agrees with the first thesis: patent infringement should require intentional conduct of a certain sort. However, the response disagrees with the second thesis: even if patent infringement requires such intent, liability would, in my view, still be “ strict.

The pinning quantum phase transition in a Tonks Girardeau gas: diagnostics by ground state fidelity and the Loschmidt echo

We study the pinning quantum phase transition in a Tonks-Girardeau gas, both in equilibrium and out-of-equilibrium, using the ground state fidelity and the Loschmidt echo as diagnostic tools. The ground state fidelity (GSF) will have a dramatic decrease when the atomic density approaches the commensurate density of one particle per lattice well. This decrease is a signature of the pinning transition from the Tonks to the Mott insulating phase. We study the applicability of the fidelity for diagnosing the pinning transition in experimentally realistic scenarios. Our results are in excellent agreement with recent experimental work. In addition, we explore the out of equilibrium dynamics of the gas following a sudden quench with a lattice potential. We find all properties of the ground state fidelity are reflected in the Loschmidt echo dynamics i.e., in the non equilibrium dynamics of the Tonks-Girardeau gas initiated by a sudden quench of the lattice potential

The Evolution of Normative Legal Scholarship: The Case of Copyright Discourse

Legal scholarship’s central function is to provide normative advice about the law. However, some academics have challenged the imp ortance of such scholarship. Pierre Schlag argues that this function of legal scholarship is “unravelling” because judges and legislators do not listen to academic opinions. This unravelling would seem to be present in the field of copyright law where numerous instances suggest that normative legal scholarship is ignored. However, copyright scholarship has evolved to overcome this problem. Today the most influential copyright scholarship comes not in law reviews or similar traditional academic outlets, but through publicly oriented books and social media. Rather than aim normative advice to lawmakers, scholars give their advice to the public generally. The public then hold the lawmakers accountable for enacting bad laws. In this way, academics can retain their position as normative advice giver