Shot noise and photon-induced correlations in 500 GHz SIS detectors

Photon-induced current correlations in SIS detectors can result in an output noise that is greater or less than shot noise. Evidence of these correlations had been observed for 100 GHz rf by accurate noise measurements as reported in our previous work. We now present a detailed analysis of these current correlations for frequencies between 100 and 500 GHz. We also report new measurements of photon-induced noise in a 490 GHz SIS mixer, and discuss the Gaussian beam techniques used to eliminate the thermal background radiation. For small 490 GHz rf power, the output noise is equal to shot noise. The results of the 100 and 490 GHz photon noise measurement are summarized in context to shot noise and the effect of the current correlations predicted by the theoretical model

Some local--global phenomena in locally finite graphs

In this paper we present some results for a connected infinite graph $G$ with finite degrees where the properties of balls of small radii guarantee the existence of some Hamiltonian and connectivity properties of $G$. (For a vertex $w$ of a graph $G$ the ball of radius $r$ centered at $w$ is the subgraph of $G$ induced by the set $M_r(w)$ of vertices whose distance from $w$ does not exceed $r$). In particular, we prove that if every ball of radius 2 in $G$ is 2-connected and $G$ satisfies the condition $d_G(u)+d_G(v)\geq |M_2(w)|-1$ for each path $uwv$ in $G$, where $u$ and $v$ are non-adjacent vertices, then $G$ has a Hamiltonian curve, introduced by K\"undgen, Li and Thomassen (2017). Furthermore, we prove that if every ball of radius 1 in $G$ satisfies Ore's condition (1960) then all balls of any radius in $G$ are Hamiltonian.Comment: 18 pages, 6 figures; journal accepted versio

On Morals, Markets, and Climate Change: Exploring Pope Francis’ Challenge

The relation between Culture and Business has caught researchers’ attention long ago; itis not hard to find studies relating to these topics. According to Hofstede et al. (2010, p.18), Hampden-Turner and Trompenaars (2012, p. 8), and Erez and Gati (2004, p. 5),culture can be defined in many levels, for example, organizational culture, and national culture. The field of Business also contains several disciplines, for example, International Business Management, Project Management, and Project Governance. However, not somany studies can be found studying the relation between National Culture and Project Governance; therefore, this study is focused on this relation.This study is designed following a qualitative approach in order to clarify the relation between National Culture and Project Governance Principles. Case studies are used targeting the IT industry of three countries, Spain, Sweden, and Taiwan. These cases also contain the classical theory of cultural dimensions from Hofstede. Hofstede’s dimensionsare Power Distance (PDI), Individualism vs. Collectivism (IDV), Uncertainty Avoidance(UAI), Masculinity vs. Femininity (MAS), Long-term Orientation (LTO), and Indulgencevs. Restraint (IDU). They are applied in this study for distinguishing the differences between countries. This study is also based on the definition of Project GovernancePrinciples from Garland (2009), Klakegg (2008), and Müller et al. (2013). ProjectGovernance Principles are split into two categories as well, hard/ structural principles andsoft/ behaviour principles.In order to clarify the link between National Culture and Project Governance Principles,this thesis’ authors interviewed 19 people, including 10 project managers and 9 experts.All of them have a long experience dealing with Project Management in the three selected countries. Their answers are based on the knowledge and experience of Project Management and Project Governance, as well as their opinions about their own national culture. After analysing the interviews, the authors consider that differences between these three countries in Project Governance and Project Governance Principles do exist. On the other hand, there are also some similar parts, for example, the influence ofcustomers’ orientation and preference. Moreover, respondents, Project Managers and Experts, all mentioned it is also necessary to be aware of the globalized environment, inother words, there is no influence of a single national culture in one country anymore.However, they all admit the importance of their own national culture as well. All these findings from this study encourage further and deeper study in the future

Rapid Water Reduction to H_2 Catalyzed by a Cobalt Bis(iminopyridine) Complex

A cobalt bis(iminopyridine) complex is a highly active electrocatalyst for water reduction, with an estimated apparent second order rate constant k_(app) ≤ 10^7 M^(–1)s^(–1) over a range of buffer/salt concentrations. Scan rate dependence data are consistent with freely diffusing electroactive species over pH 4–9 at room temperature for each of two catalytic reduction events, one of which is believed to be ligand based. Faradaic H_2 yields up to 87 ± 10% measured in constant potential electrolyses (−1.4 V vs SCE) confirm high reactivity and high fidelity in a catalyst supported by the noninnocent bis(iminopyridine) ligand. A mechanism involving initial reduction of Co^(2+) and subsequent protonation is proposed

Time-Reversal Symmetry and Universal Conductance Fluctuations in a Driven Two-Level System

In the presence of time-reversal symmetry, quantum interference gives strong corrections to the electric conductivity of disordered systems. The self-interference of an electron wavefunction traveling time-reversed paths leads to effects such as weak localization and universal conductance fluctuations. Here, we investigate the effects of broken time-reversal symmetry in a driven artificial two-level system. Using a superconducting flux qubit, we implement scattering events as multiple Landau-Zener transitions by driving the qubit periodically back and forth through an avoided crossing. Interference between different qubit trajectories give rise to a speckle pattern in the qubit transition rate, similar to the interference patterns created when coherent light is scattered off a disordered potential. Since the scattering events are imposed by the driving protocol, we can control the time-reversal symmetry of the system by making the drive waveform symmetric or asymmetric in time. We find that the fluctuations of the transition rate exhibit a sharp peak when the drive is time-symmetric, similar to universal conductance fluctuations in electronic transport through mesoscopic systems