Entanglement and the Quantum Brachistochrone Problem

Entanglement is closely related to some fundamental features of the dynamics of composite quantum systems: quantum entanglement enhances the "speed" of evolution of certain quantum states, as measured by the time required to reach an orthogonal state. The concept of "speed" of quantum evolution constitutes an important ingredient in any attempt to determine the fundamental limits that basic physical laws impose on how fast a physical system can process or transmit information. Here we explore the relationship between entanglement and the speed of quantum evolution in the context of the quantum brachistochrone problem. Given an initial and a final state of a composite system we consider the amount of entanglement associated with the brachistochrone evolution between those states, showing that entanglement is an essential resource to achieve the alluded time-optimal quantum evolution.Comment: 6 pages, 3 figures. Corrected typos in Eqs. 1 and

Magnetic correlations of the quasi-one-dimensional half-integer spin-chain antiferromagnets SrM2M_2V2_2O8_8 (MM = Co, Mn)

Magnetic correlations of two iso-structural quasi-one-dimensional (1D) antiferromagnetic spin-chain compounds Sr$M_2$V$_2$O$_8$ ($M$ = Co, Mn) have been investigated by magnetization and powder neutron diffraction. Two different collinear antiferromagnetic (AFM) structures, characterized by the propagation vectors, $k$ = (0 0 1) and $k$ = (0 0 0), have been found below $\sim$ 5.2 K and $\sim$ 42.2 K for the Co- and Mn-compounds, respectively. For the Mn-compound, AFM chains (along the $c$ axis) order ferromagnetically within the $ab$ plane, whereas, for the Co-compound, AFM chains order ferro-/antiferromagnetically along the $a/b$ direction. The critical exponent study confirms that the Co- and Mn-compounds belong to the Ising and Heisenberg universality classes, respectively. For both compounds, short-range spin-spin correlations are present over a wide temperature range above $T_N$. The reduced ordered moments at base temperature (1.5 K) indicate the presence of quantum fluctuations in both compounds due to the quasi-1D magnetic interactions.Comment: 14 pages, 10 figures, 9 table

Exploring a Non-Minimal Sterile Neutrino Model Involving Decay at IceCube and Beyond

We study the phenomenology of neutrino decay together with neutrino oscillations in the context of eV-scale sterile neutrinos. We review the formalism of visible neutrino decay in which one of the decay products is a neutrino that potentially can be observed. We apply the formalism developed for decay to the recent sterile neutrino search performed by IceCube with TeV neutrinos. We show that for $\nu_4$ lifetime $\tau_4/m_4 \lesssim 10^{-16} {\rm eV^{-1}s}$, the interpretation of the high-energy IceCube analysis can be significantly changed.Comment: 12 pages, 7 figures. Find code at: https://github.com/arguelles/nuSQUIDSDeca

Noisy quantum Monty Hall game

The influence of spontaneous emission channel and generalized Pauli channel on quantum Monty Hall Game is analysed. The scheme of Flittney and Abbott is reformulated using the formalism of density matrices. Optimal classical strategies for given quantum strategies are found. The whole presented scheme illustrates how quantum noise may change the odds of a zero-sum game.Comment: 10 pages, 3 figure

Police bail without charge: The human rights implications

Whilst the power of the police to release a person on bail prior to trial has existed for centuries, the power to release on bail a person suspected of but not charged with a criminal offence has been available to the police only since 1925. The power to attach conditions to pre-charge bail is of very recent origin, having been introduced for the first time in 2003 but rapidly expanded since then. Whilst imposing restrictions on the liberty of a person should, constitutionally, be reserved to the judiciary, the fact that it was originally conceived, in part at least, as a mechanism for enhancing liberty reduced the constitutional tension created by allowing members of the executive such powers. However, the changing role of arrest in the investigation of crime and the granting of extensive powers to the police to impose bail conditions means that the police now have the ability to place controls on people not charged with a criminal offence for extended periods of time. It is argued here that this is in breach of the right to liberty under Article 5 of the European Convention on Human Rights and, in practice, may also breach other Convention rights

A multipole array magnetic spring

© 2005 IEEE.This paper presents research on a magnetic spring concept, which has application to the development of a vibration isolation table. Features of the design are scalable, noncontact load bearing and a single degree of instability.Will Robertson, Ben Cazzolato, and Anthony Zande

Leptodontium stellatifolium (Pottiaceae, Bryophyta) en la Isla Réunion, un rango de disyunción significativo

A species of mountainous regions of Latin America, Leptodontium stellatifolium, is reported from La Réunion Island in the Indian Ocean. This is a major geographic range disjunction. The species is illustrated and described from La Réunion material, and its considerable variation across its range and within La Réunion is discussed. Explanations of its distribution are suggested in terms of both ancient sky and ocean island spore dispersal, and recent, human-mediated introduction. We provide a key for species of Leptodontium occurring on La Réunion.Leptodontium stellatifolium (Pottiaceae, Bryophyta) en la Isla Réunion, un rango de disyunción significativo. Leptodontium stellatifolium, una especie de las regiones montañosas de América Latina, es registrada para La Réunion en el Océano Indico. Esta es una disyunción geográfica significativa. La especie es descrita e ilustrada y se discute su variación a lo largo del rango de distribución y dentro de la isla. Se sugiere que su distribución puede deberse a una dispersión antigua por aire y a través de las islas o bien fue recientemente introducida por el hombre. Se incluye una clave de las especies de Leptodontium en La Réunion

The Purposes of National Associations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68538/2/10.1177_089976407200100403.pd