Conceptualising neuroscience-based leadership behaviour

This thesis primarily focuses on conceptualising Neuroscience Based Leadership (NSBL) by providing a working definition of NSBL, describing the foundational concepts and core behaviours of neuroscience-based leadership (NSBL), and presenting a conceptual framework that integrates interdisciplinary perspectives on leadership behaviour. This was achieved by: 1. Reviewing existing relevant scientific literature and highlighting current knowledge gaps in the conceptualisations of NSBL using Leadership Behaviour, Social Cognitive Neuroscience (SCN), and Neuropsychotherapy (NP) 2. Conducting a small-scale research project using semi-structured, in-depth interviews with three neuroscientists who have employed neuroscience-based diagnostics in leadership development within a corporate context. This study’s key findings reveal key conceptual themes with the following theoretical propositions that underpin NSBL key behaviours: social safety is a primary operating principle; conscious thinking and nonconscious processes drive behaviour; nature-nurture dynamics influence behaviour; experienced-based neuroplasticity drives change; and overlapping large-scale brain networks enable information processing in the brain. 3. Designing and implementing a qualitative Delphi study involving 33 experienced professionals in NSBL to explore how NSBL is defined, conceptualise NSBL as a different domain of leadership behaviour, and provide descriptors of NSBL key behaviours 4. Adopting a case study approach involving an organisational psychologist experienced in Neuropsychotherapy and drawing on his views and experiences to produce a single-case study of NSBL within the context of organisational psychology and applied organisational neuroscience (AONS). 5. Undertaking a reflective and critical review of the four pieces of research and proposing a theoretical framework of NSBL, specifically within formal organisations, to inform, support, foster and develop future NSBL-based behaviour. The contribution of this study is broad in that it offers a working definition of neuroscience-based leadership and an interdisciplinary conceptual framework to guide practitioners and further research. This conceptual framework integrates theoretical propositions regarding leadership behaviour from Leadership Behaviour theory, Social Cognitive and Affective Neuroscience, and Neuropsychotherapy. The theoretical framework of NSBL addresses gaps in the literature by differentiating four domains of NSBL: stress resilience-focused core behaviours, affect and emotional-focused core behaviours, relationship-focused core behaviours, and task-focused core behaviours. It also provides neuroscientific concepts that underpin behaviour. The contribution to practice is that this study advances the understanding of how formal organisations can apply a neuroscientific lens to inform the design of leadership development interventions. This integrative, interdisciplinary theoretical framework can be used for leadership coaching at an individual level. At the group level, it can facilitate team building. It can provide a neuroscientific language for mental experience at an organisational level, thereby enhancing the explanatory power of concepts in leadership and organisational behaviour

Ultrafast QND measurements based on diamond-shape artificial atom

We propose a Quantum Non Demolition (QND) read-out scheme for a superconducting artificial atom coupled to a resonator in a circuit QED architecture, for which we estimate a very high measurement fidelity without Purcell effect limitations. The device consists of two transmons coupled by a large inductance, giving rise to a diamond-shape artificial atom with a logical qubit and an ancilla qubit interacting through a cross-Kerr like term. The ancilla is strongly coupled to a transmission line resonator. Depending on the qubit state, the ancilla is resonantly or dispersively coupled to the resonator, leading to a large contrast in the transmitted microwave signal amplitude. This original method can be implemented with state of the art Josephson parametric amplifier, leading to QND measurements in a few tens of nanoseconds with fidelity as large as 99.9 %.Comment: 5 pages, 4 figure

Measurement of the Current-Phase Relation in Josephson Junctions Rhombi Chains

We present low temperature transport measurements in one dimensional Josephson junctions rhombi chains. We have measured the current phase relation of a chain of 8 rhombi. The junctions are either in the classical phase regime with the Josephson energy much larger than the charging energy, $E_{J}\gg E_{C}$, or in the quantum phase regime where $E_{J}/E_{C}\approx 2$. In the strong Josephson coupling regime ($E_{J}\gg E_{C} \gg k_{B}T$) we observe a sawtooth-like supercurrent as a function of the phase difference over the chain. The period of the supercurrent oscillations changes abruptly from one flux quantum $\Phi_{0}$ to half the flux quantum $\Phi_{0}/2$ as the rhombi are tuned in the vicinity of full frustration. The main observed features can be understood from the complex energy ground state of the chain. For $E_{J}/E_{C}\approx 2$ we do observe a dramatic suppression and rounding of the switching current dependence which we found to be consistent with the model developed by Matveev et al.(Phys. Rev. Lett. {\bf 89}, 096802(2002)) for long Josephson junctions chains.Comment: to appear in Phys. Rev.

Nanosecond quantum state detection in a current biased dc SQUID

This article presents our procedure to measure the quantum state of a dc SQUID within a few nanoseconds, using an adiabatic dc flux pulse. Detection of the ground state is governed by standard macroscopic quantum theory (MQT), with a small correction due to residual noise in the bias current. In the two level limit, where the SQUID constitutes a phase qubit, an observed contrast of 0.54 indicates a significant loss in contrast compared to the MQT prediction. It is attributed to spurious depolarization (loss of excited state occupancy) during the leading edge of the adiabatic flux measurement pulse. We give a simple phenomenological relaxation model which is able to predict the observed contrast of multilevel Rabi oscillations for various microwave amplitudes.Comment: 10 pages, 8 figure

Decoherence processes in a current biased dc SQUID

A current bias dc SQUID behaves as an anharmonic quantum oscillator controlled by a bias current and an applied magnetic flux. We consider here its two level limit consisting of the two lower energy states | 0 \right> and | 1 \right>. We have measured energy relaxation times and microwave absorption for different bias currents and fluxes in the low microwave power limit. Decoherence times are extracted. The low frequency flux and current noise have been measured independently by analyzing the probability of current switching from the superconducting to the finite voltage state, as a function of applied flux. The high frequency part of the current noise is derived from the electromagnetic environment of the circuit. The decoherence of this quantum circuit can be fully accounted by these current and flux noise sources.Comment: 4 pages, 4 figure

Coherent oscillations in a superconducting multi-level quantum system

We have observed coherent time evolution of states in a multi-level quantum system, formed by a current-biased dc SQUID. The manipulation of the quantum states is achieved by resonant microwave pulses of flux. The number of quantum states participating in the coherent oscillations increases with increasing microwave power. Quantum measurement is performed by a nanosecond flux pulse which projects the final state onto one of two different voltage states of the dc SQUID, which can be read out

Experimental demonstration of Aharonov-Casher interference in a Josephson junction circuit

A neutral quantum particle with magnetic moment encircling a static electric charge acquires a quantum mechanical phase (Aharonov-Casher effect). In superconducting electronics the neutral particle becomes a fluxon that moves around superconducting islands connected by Josephson junctions. The full understanding of this effect in systems of many junctions is crucial for the design of novel quantum circuits. Here we present measurements and quantitative analysis of fluxon interference patterns in a six Josephson junction chain. In this multi-junction circuit the fluxon can encircle any combination of charges on five superconducting islands, resulting in a complex pattern. We compare the experimental results with predictions of a simplified model that treats fluxons as independent excitations and with the results of the full diagonalization of the quantum problem. Our results demonstrate the accuracy of the fluxon interference description and the quantum coherence of these arrays

Evidence of two-dimensional macroscopic quantum tunneling of a current-biased DC-SQUID

The escape probability out of the superconducting state of a hysteretic DC-SQUID has been measured at different values of the applied magnetic flux. At low temperature, the escape current and the width of the probability distribution are temperature independent but they depend on flux. Experimental results do not fit the usual one-dimensional (1D) Macroscopic Quantum Tunneling (MQT) law but are perfectly accounted for by the two-dimensional (2D) MQT behaviour as we propose here. Near zero flux, our data confirms the recent MQT observation in a DC-SQUID \cite{Li02}.Comment: 4 pages, 4 figures Accepted to PR

First experimental evidence of one-dimensional plasma modes in superconducting thin wires

We have studied niobium superconducting thin wires deposited onto a SrTiO$_{3}$ substrate. By measuring the reflection coefficient of the wires, resonances are observed in the superconducting state in the 130 MHz to 4 GHz range. They are interpreted as standing wave resonances of one-dimensional plasma modes propagating along the superconducting wire. The experimental dispersion law, $\omega$ versus $q$, presents a linear dependence over the entire wave vector range. The modes are softened as the temperature increases close the superconducting transition temperature. Very good agreement are observed between our data and the dispersion relation predicted by Kulik and Mooij and Sch\"on.Comment: Submitted to Physical review Letter

Fabrication of stable and reproducible sub-micron tunnel junctions

We have performed a detailed study of the time stability and reproducibility of sub-micron $Al/AlO_{x}/Al$ tunnel junctions, fabricated using standard double angle shadow evaporations. We have found that by aggressively cleaning the substrate before the evaporations, thus preventing any contamination of the junction, we obtained perfectly stable oxide barriers. We also present measurements on large ensembles of junctions which prove the reproducibility of the fabrication process. The measured tunnel resistance variance in large ensembles of identically fabricated junctions is in the range of only a few percents. Finally, we have studied the effect of different thermal treatments on the junction barrier. This is especially important for multiple step fabrication processes which imply annealing the junction.Comment: 4 pages, 3 figure