On maximal subgroups of the multiplicative group of a division algebra

This note studies the question whether a multiplicative group of a division ring has a maximal subgroup. It is published in J. Algebra. This is a reputable journal in the subject algebra. Most of submitted papers from 5* schools in RAE was in this journal.

Noise resilience and entanglement evolution in two nonequivalent classes of quantum algorithms

The speedup provided by quantum algorithms with respect to their classical counterparts is at the origin of scientific interest in quantum computation. However, the fundamental reasons for such a speedup are not yet completely understood and deserve further attention. In this context, the classical simulation of quantum algorithms is a useful tool that can help us in gaining insight. Starting from the study of general conditions for classical simulation, we highlight several important differences between two nonequivalent classes of quantum algorithms. We investigate their performance under realistic conditions by quantitatively studying their resilience with respect to static noise. This latter refers to errors affecting the initial preparation of the register used to run an algorithm. We also compare the evolution of the entanglement involved in the different computational processes.

Low SNR Capacity for MIMO Rician and Rayleigh-Product Fading Channels with Single Co-channel Interferer and Noise

This paper studies the ergodic capacity of multiple-input multiple-output (MIMO) systems with a single co-channel interferer in the low signal-to-noise-ratio (SNR) regime. Two MIMO models namely Rician and Rayleigh-product channels are investigated. Exact analytical expressions for the minimum energy per information bit, Eb/N0min, and wideband slope, S0, are derived for both channels. Our results show that the minimum energy per information bit is the same for both channels while their wideband slopes differ significantly. Further, the impact of the numbers of transmit and receive antennas, the Rician K factor, the channel mean matrix and the interference-to-noise-ratio (INR) on the capacity, is addressed. Results indicate that interference degrades the capacity by increasing the required minimum energy per information bit and reducing the wideband slope. Simulation results validate our analytical results.

"The pride of noise": drums and their repercussions in early modern England

This article draws on a wide range of literary and archival sources in order to explore the cultural resonances of drumming in England during the 16th and 17th centuries. It concentrates not on instrument design and playing techniques but on the varied meanings that contemporaries attached to the ubiquitous sound of the drum. The discussion begins and ends with the unmistakable military associations of drumming. In between, consideration is also given to a range of interconnected but sometimes contradictory resonances that appear to have endowed drums with considerable cultural significance. Drums spoke, for example, of authority and they worked hard to impose order in urban streets. They also played their part in the contemporary culture of punishment, and many miscreants were subjected to the humiliation of public percussion. Beyond this, drums were particularly potent in their ability to express masculinity, and female drummers were rare and remarkable. The primal potency of the instrument also rendered it valuable to the insubordinate, and rioters—like soldiers— were regularly called together 'by the drum'. Lastly, the sound of the drum was sometimes intensely festive and could also be used to publicize special events such as dramatic performances and the display of curiosities. The repercussions of drumming were thus varied, and confusion sometimes resulted when the different possibilities became entangled.

A geometric analysis of the effects of noise on Berry phase

In this work we describe the effect of classical and quantum noise on the Berry phase. It is not a topical review article but rather an overview of our work in this field aiming at giving a simple pictorial intuition of our results.