Crossover from weak to strong coupling regime in dispersive circuit QED

We study the decoherence of a superconducting qubit due to the dispersive coupling to a damped harmonic oscillator. We go beyond the weak qubit-oscillator coupling, which we associate with a phase Purcell effect, and enter into a strong coupling regime, with qualitatively different behavior of the dephasing rate. We identify and give a physicaly intuitive discussion of both decoherence mechanisms. Our results can be applied, with small adaptations, to a large variety of other physical systems, e. g. trapped ions and cavity QED, boosting theoretical and experimental decoherence studies.Comment: Published versio

Bioresorbable scaffold - A magic bullet for the treatment of coronary artery disease?

Today, drug-eluting metal stents are considered the gold standard for interventional treatment of coronary artery disease. While providing inhibition of neointimal hyperplasia, drug-eluting metal stents have many limitations such as the risk of late and very late stent thrombosis, restriction of vascular vasomotion and chronic local inflammatory reaction due to permanent implantation of a 'metallic cage', recognized as a foreign body. Bioresorbable scaffold stents (BRS) are a new solution, which is trying to overcome the limitation of the 'metallic cage'. This structure provides short-term scaffolding of the vessel and then disappears, leaving nothing behind. The purpose of this review is to present the theoretical rationale for the use of BRS and to outline the clinical outcomes associated with their use in terms of data obtained from RCTs, clinical trials, registries and real life use. We have also tried to answer all questions on this intervention based on available data, with a focus on ABSORB BVS (Abbott Vascular, Santa Clara, USA). We consider that this new technology can be the "magic bullet" to treat coronary artery disease

Quantum nondemolition-like, fast measurement scheme for a superconducting qubit

We present a measurement protocol for a flux qubit coupled to a dc-Superconducting QUantum Interference Device (SQUID), representative of any two-state system with a controllable coupling to an harmonic oscillator quadrature, which consists of two steps. First, the qubit state is imprinted onto the SQUID via a very short and strong interaction. We show that at the end of this step the qubit dephases completely, although the perturbation of the measured qubit observable during this step is weak. In the second step, information about the qubit is extracted by measuring the SQUID. This step can have arbitrarily long duration, since it no longer induces qubit errors.Comment: published version, minor correction

Outcomes following aortic valve procedures in 201 complex congenital heart disease cases:results from the UK National Audit

OBJECTIVES: Some patients with complex congenital heart disease (cCHD) also require aortic valve (AoV) procedures. These cases are considered high risk but their outcome has not been well characterized. We aim to describe these scenarios in the current practice, and provide outcome data for counselling and decision-making. METHODS: This was a retrospective study using the UK National Congenital Heart Disease Audit data on cCHD patients undergoing aortic valve replacement, balloon dilation (balloon aortic valvuloplasty) or surgical repair (surgical aortic valve repair) between 2000 and 2012. Coarsened exact matching was used to pair cCHD with patients undergoing AoV procedures for isolated valve disease. RESULTS: A total of 201 patients with a varied spectrum of cCHD undergoing 242 procedures were included, median age 9.4 years (1 day–65 years). Procedure types were: balloon aortic valvuloplasty (n = 31, 13%), surgical aortic valve repair (n = 57, 24%) and aortic valve replacement (n = 154, 63%). Mortality at 30 days was higher in neonates (21.8% vs 5.3%, P = 0.02). Survival at 10 years was 83.1%, freedom from aortic valve replacement 83.8% and freedom from balloon aortic valvuloplasty/surgical aortic valve repair 86.3%. Neonatal age (P < 0.001), single ventricle (P = 0.08), concomitant Fontan/Glenn (P = 0.002) or aortic arch procedures (0.02) were associated with higher mortality. cCHD patients had lower survival at 30 days (93% vs 100%, P = 0.003) and at 10 years (86.4% vs 96.1%, P = 0.005) compared to matched isolated AoV disease patients. CONCLUSIONS: AoV procedures in cCHD can be performed with good results outside infancy, but with higher mortality than in isolated AoV disease. Neonates and patients with single ventricle defects, especially those undergoing concomitant Fontan/Glenn, have worse outcomes

Aspects of Integrability in N =4 SYM

Various recently developed connections between supersymmetric Yang-Mills theories in four dimensions and two dimensional integrable systems serve as crucial ingredients in improving our understanding of the AdS/CFT correspondence. In this review, we highlight some connections between superconformal four dimensional Yang-Mills theory and various integrable systems. In particular, we focus on the role of Yangian symmetries in studying the gauge theory dual of closed string excitations. We also briefly review how the gauge theory connects to Calogero models and open quantum spin chains through the study of the gauge theory duals of D3 branes and open strings ending on them. This invited review, written for Modern Physics Letters-A, is based on a seminar given at the Institute of Advanced Study, Princeton.Comment: Invited brief review for Mod. Phys. Lett. A based on a talk at I.A.S, Princeto

Classical Exchange Algebra of the Superstring on S^5 with the AdS-time

A classical exchange algebra of the superstring on S^5 with the AdS-time is shown on the light-like plane. To this end we use the geometrical method of which consistency is guaranteed by the classical Yang-Baxter equation. The Dirac method does not work, there being constraints which contain first-class and second-class and one can disentangle with each other keeping the isometry hardly.Comment: 12 pages, v2: argument on alternative representation of S^5 spherical functions added, typos corrected, one reference added, matches journal versio

Einstein’s Equation in Nuclear and Solar Energy

Starting from the equation of Einstein (E = m·c2), the chapter proposes a simple and fundamental presentation of the fission and fusion principles, together with some of their applications: nuclear reactors and nuclear propulsion vessels and submarines. Fission and fusion are chosen between the multiple forms of energy, as being the most important forms of nuclear energy, directly related with the equation of Einstein. Some characteristics of solar energy, produced from the fusion process inside the Sun, are deducted from the same equation of Einstein: thermal power of solar radiation; specific power of solar radiation; surface temperature of the Sun; solar constant on different planets, etc. The yearly variation of the solar radiation on each planet of the solar system is also presented