Robustness of quantum gates in the presence of noise

We define several quantitative measures of the robustness of a quantum gate against noise. Exact analytic expressions for the robustness against depolarizing noise are obtained for all bipartite unitary quantum gates, and it is found that the controlled-NOT gate is the most robust two-qubit quantum gate, in the sense that it is the quantum gate which can tolerate the most depolarizing noise and still generate entanglement. Our results enable us to place several analytic upper bounds on the value of the threshold for quantum computation, with the best bound in the most pessimistic error model being p(th)less than or equal to0.5.

Psychoanalytic perspectives on substance use and antisocial personality disorder

Psychoanalysis and related psychodynamic psychotherapies have historically had a limited engagement with substance use and antisocial personality disorders. This in part reflects an early preoccupation with 'transference neuroses' and in part reflects later de-emphasis of diagnosis and focus on therapeutic process. Nonetheless, psychoanalytic perspectives can usefully inform thinking about approaches to treatment of such disorders and there are psychoanalytic constructs that have specific relevance to their treatment. This paper reviews some prominent strands of psychoanalytic thinking as they pertain to the treatment of substance abuse and antisocial personality disorders. It is argued that, while Freudian formulations lead to a primarily pessimistic view of the prospect of treatment of such disorders, both the British object relations and the North American self psychology traditions suggest potentially productive approaches. Finally the limited empirical evidence from brief psycho dynamically informed treatments of substance use disorders is reviewed. It is concluded that such treatments are not demonstrably effective but that, since no form of psychotherapy has established high efficacy with substance use disorders, brief psychdynamic therapies are not necessarily of lesser value than other treatments and may have specific value for particular individuals and in particular treatment contexts.

Women, careers and information technology: An introduction

This special issue revisits the relationship between women, work and technology, focusing specifically on gender equity in information technology (IT) employment. Along with theoretical contestation over the broader relationship between gender and technology, arguments about the prospects for women in IT employment have ranged from optimistic to pessimistic extremes. On the one hand, optimists have envisaged a more gender-egalitarian workforce based on new occupations lacking traditional gender markers, and 'young' firms offering positive flexibilities and equal employment opportunity protections. On the other hand, pessimists anticipate that ongoing male dominance over tedmology and competitive pressures in the IT sector will ensure that the most prestigious and highly rewarded jobs remain concentrated in male hands, even as teclmologies and jobs are themselves transformed.