Long-range Heisenberg models in quasi-periodically driven crystals of trapped ions

We introduce a theoretical scheme for the analog quantum simulation of long-range XYZ models using current trapped-ion technology. In order to achieve fully-tunable Heisenberg-type interactions, our proposal requires a state-dependent dipole force along a single vibrational axis, together with a combination of standard resonant and detuned carrier drivings. We discuss how this quantum simulator could explore the effect of long-range interactions on the phase diagram by combining an adiabatic protocol with the quasi-periodic drivings and test the validity of our scheme numerically. At the isotropic Heisenberg point, we show that the long-range Hamiltonian can be mapped onto a non-linear sigma model with a topological term that is responsible for its low-energy properties, and we benchmark our predictions with Matrix-Product-State numerical simulations.Comment: closer to published versio

Simulation of Jahn-Teller-Dicke Magnetic Structural Phase Transition with Trapped Ions

We study theoretically the collective E$\otimes$e Jahn-Teller-Dicke distortion in a system of trapped ions. We focus in the limit of infinite range interactions in which an ensemble of effective spins interacts with two collective vibrational modes with U(1) symmetric couplings. Our model is exactly solvable in the thermodynamical limit and it is amenable to be solved by exact numerical diagonalization for a moderate number of ions. We show that trapped ions are ideally suited to study the emergence of spontaneous symmetry breaking of a continuous symmetry and magnetic structural phase transition in a mesoscopic system.Comment: 19 pages, 7 figure

Excitation Enhancement of a Quantum Dot Coupled to a Plasmonic Antenna

Plasmonic antennas are key elements to control the luminescence of quantum emitters. However, the antenna's influence is often hidden by quenching losses. Here, the luminescence of a quantum dot coupled to a gold dimer antenna is investigated. Detailed analysis of the multiply excited states quantifies the antenna's influence on the excitation intensity and the luminescence quantum yield separately

Robust Trapped-Ion Quantum Logic Gates by Continuous Dynamical Decoupling

We introduce a novel scheme that combines phonon-mediated quantum logic gates in trapped ions with the benefits of continuous dynamical decoupling. We demonstrate theoretically that a strong driving of the qubit decouples it from external magnetic-field noise, enhancing the fidelity of two-qubit quantum gates. Moreover, the scheme does not require ground-state cooling, and is inherently robust to undesired ac-Stark shifts. The underlying mechanism can be extended to a variety of other systems where a strong driving protects the quantum coherence of the qubits without compromising the two-qubit couplings.Comment: Slightly longer than the published versio

Unveiling the near-infrared structure of the massive-young stellar object NGC 3603 IRS 9A with sparse aperture masking and spectroastrometry

Contemporary theory holds that massive stars gather mass during their initial phases via accreting disk-like structures. However, conclusive evidence for disks has remained elusive for the most massive young objects. This is mainly due to significant observational challenges. Incisive studies, even targeting individual objects, are therefore relevant to the progression of the field. NGC 3603 IRS 9A* is a young massive stellar object still surrounded by an envelope of molecular gas. Previous mid-infrared observations with long-baseline interferometry provided evidence for a disk of 50 mas diameter at its core. This work aims at a comprehensive study of the physics and morphology of IRS 9A at near-infrared wavelengths. New sparse aperture masking interferometry data taken with NACO/VLT at Ks and Lp filters were obtained and analysed together with archival CRIRES spectra of the H2 and BrG lines. The calibrated visibilities recorded at Ks and Lp bands suggest the presence of a partially resolved compact object of 30 mas at the core of IRS 9A, together with the presence of over-resolved flux. The spectroastrometric signal of the H2 line shows that this spectral feature proceeds from the large scale extended emission (300 mas) of IRS 9A, while the BrG line appears to be formed at the core of the object (20 mas). This scenario is consistent with the brightness distribution of the source for near- and mid-infrared wavelengths at various spatial scales. However, our model suffers from remaining inconsistencies between SED modelling and the interferometric data. Moreover, the BrG spectroastrometric signal indicates that the core of IRS 9A exhibits some form of complexity such as asymmetries in the disk. Future high-resolution observations are required to confirm the disk/envelope model and to flesh out the details of the physical form of the inner regions of IRS 9A.Comment: Accepted to be published in Astronomy & Astrophysics, 13 pages, 14 figure

Psychological Therapists’ Wellbeing in the Context of IAPT-NHS: A Foucauldian Discourse Analysis

This study set out to gain in depth and critical understanding of how psychological therapists working in IAPT-NHS services construct the concept of their wellbeing at work. Foucauldian Discourse Analysis (FDA) was used to identify the available discourses mobilised by these practitioners and map out their impact on subjectivity and practice, as well as the role of the specific NHS-IAPT context. Ten psychological therapists working in IAPT services across two East London NHS Trusts were interviewed, using a semi-structured interview which also featured a visual task to elicit information. The interview narratives were analysed using FDA through the lens of a moderate social constructionist position. The analysis identified four main discursive constructions of wellbeing: (1) wellbeing as an individual responsibility; (2) wellbeing as a collective responsibility; (3) wellbeing as self-actualisation; and (4) wellbeing as productivity. Each presented a picture of duality and contradiction, delineated by the subject positions made available. Notably, for the first two constructions, the subject positions of responsible and irresponsible alternated between the individual and the service, with particular impact on the ability to voice wellbeing difficulties at work. Subject positions of the good/ideal therapist and the good employee, corresponding to the latter two constructions, were mediated by the introduction of IAPT as a sub-context. IAPT was constructed as an inflexible, target-driven system in which participants seemed unable to hold both the good/ideal therapist and good employee position, resulting in a constant tension that seemed to only be resolved by giving up one of the two positions. The conclusion addresses the benefits of approaching the issue of psychological therapists’ wellbeing at work beyond the individualistic, neoliberal perspective, with particular recommendations to: (1) direct more funding to protect the NHS’s therapeutic function, preventing further expansion of the market discourse into mental health services; (2) promote congruence between policies and practices at work, aligned with a collectivist perspective of wellbeing where both the individual and the system share responsibility and support; and (3) increase IAPT’s flexibility to adapt appropriately to diversity

Engineering Time-Reversal Invariant Topological Insulators With Ultra-Cold Atoms

Topological insulators are a broad class of unconventional materials that are insulating in the interior but conduct along the edges. This edge transport is topologically protected and dissipationless. Until recently, all existing topological insulators, known as quantum Hall states, violated time-reversal symmetry. However, the discovery of the quantum spin Hall effect demonstrated the existence of novel topological states not rooted in time-reversal violations. Here, we lay out an experiment to realize time-reversal topological insulators in ultra-cold atomic gases subjected to synthetic gauge fields in the near-field of an atom-chip. In particular, we introduce a feasible scheme to engineer sharp boundaries where the "edge states" are localized. Besides, this multi-band system has a large parameter space exhibiting a variety of quantum phase transitions between topological and normal insulating phases. Due to their unprecedented controllability, cold-atom systems are ideally suited to realize topological states of matter and drive the development of topological quantum computing.Comment: 11 pages, 6 figure

Management of Inherited, Acquired, and Iatrogenically Induced Coagulopathies in Oral Surgery

Hemostasis is the process of cessation of blood loss. Alterations of the hemostatic pathways can result in a hypercoagulable or hypocoagulable state resulting in thrombosis or hemorrhage. Common defects in hemostasis and their management, specifically the hypocoagulable state, are discussed as these defects often result in increased perioperative blood loss, which can result in compromised patient outcomes

Numerical Modelling of Industrial Induction

Induction heating is a physical process extensively used in the metallurgical industry for different applications involving metal melting. The main components of an induction heating system are an induction coil connected to a power-supply providing an alternating electric current and a conductive workpiece to be heated, placed inside the coil. The alternating current traversing the coil generates eddy currents in the workpiece and by means of ohmic losses the workpiece is heate

Non-relativistic limit in the 2+1 Dirac Oscillator: A Ramsey Interferometry Effect

We study the non-relativistic limit of a paradigmatic model in Relativistic Quantum Mechanics, the two-dimensional Dirac oscillator. Remarkably, we find a novel kind of Zitterbewegung which persists in this non-relativistic regime, and leads to an observable deformation of the particle orbit. This effect can be interpreted in terms of a Ramsey Interferometric phenomenon, allowing an insightful connection between Relativistic Quantum Mechanics and Quantum Optics. Furthermore, subsequent corrections to the non-relativistic limit, which account for the usual spin-orbit Zitterbewegung, can be neatly understood in terms of a Mach-Zehnder interferometer.Comment: RevTex4 file, color figures, submitted for publicatio