Publications related to Geometric phase

Phonon Self-Energy Corrections: To Screen, or Not to Screen

First-principles calculations of phonons are often based on the adiabatic approximation and on Brillouinzone samplings that might not always be sufficient to capture the subtleties of Kohn anomalies. These shortcomings can be addressed through corrections ...

American Physical Society2023

Spin Evolution in the Born-Oppenheimer Approximation

Jean-Philippe Ansermet, François Reuse, Klaus Maschke

The first part of this article attempts to highlight in chronological order some prominent papers that have direct connexion with the Born-Oppenheimer approximation. This timeline successively points to the role of level crossing, the notions of gauge fiel ...

WILEY-V C H VERLAG GMBH2022

Effect of collisions on non-adiabatic electron dynamics in ITG-driven microturbulence

Stephan Brunner, Justin Richard Ball

Non-adiabatic electron response leads to significant changes in ion temperature gradient (ITG) eigenmodes, leading, in particular, to fine-structures that are significantly extended along the magnetic field lines at corresponding mode rational surfaces (MR ...

2021

Simultaneous Perturbation Stochastic Approximation of the Quantum Fisher Information

Giuseppe Carleo, Julien Sebastian Gacon, Stefan Woerner

The Quantum Fisher Information matrix (QFIM) is a central metric in promising algorithms, such as Quantum Natural Gradient Descent and Variational Quantum Imaginary Time Evolution. Computing the full QFIM for a model with d parameters, however, is computat ...

VEREIN FORDERUNG OPEN ACCESS PUBLIZIERENS QUANTENWISSENSCHAF2021

Which form of the molecular Hamiltonian is the most suitable for simulating the nonadiabatic quantum dynamics at a conical intersection?

Jiri Vanicek, Seonghoon Choi

Choosing an appropriate representation of the molecular Hamiltonian is one of the challenges faced by simulations of the nonadiabatic quantum dynamics around a conical intersection. The adiabatic, exact quasidiabatic, and strictly diabatic representations ...

2020

Silicon Photonic MEMS Phase-Shifter

Niels Quack, Hamed Sattari, Teodoro Graziosi, Marcell Kristof Kiss

We present a design for an analog phase shifter based on Silicon Photonic MEMS technology. The operation principle is based on a two-step parallel plate electrostatic actuation mechanism to bring a vertically movable suspended tapered waveguide in a first ...

2019

Improved off‐resonance phase behavior using a phase‐inverted adiabatic half‐passage pulse for 13 C MRS in humans at 7 T

Rolf Gruetter, Lijing Xin, Daniel Gallichan, Eulalia Serés Roig

In vivo (13) C MRS at high field benefits from an improved SNR and spectral resolution especially when using surface coils in combination with adiabatic pulses, such as the adiabatic half-passage (AHP) pulse for (13) C excitation. However, the excitation p ...

2019

Linear collisionless dynamics of the GAM with kinetic electrons: Comparison simulations/theory

Alberto Bottino

Barely trapped and passing electrons have been recently predicted to strongly enhance the damping rate of Geodesic Acoustic Modes (GAMs) in tokamak plasmas, while keeping their real frequency almost unchanged as compared to the case with adiabatic electron ...

AMER INST PHYSICS2019

Parameters affecting thermal risk through a kinetic model under adiabatic condition: Application to liquid-liquid reaction system

Thierry Meyer

Risk of thermal runaway for epoxidation is not negligible and should be analyzed and assessed. In industry, epoxidation of vegetable oils is carried out by the oxidation of Prileschajew, involving the in situ production of percarboxylic acid from hydrogen ...

2018

Geometric phases in discrete dynamical systems

Nicolas Piro Mastracchio

In order to study the behaviour of discrete dynamical systems under adiabatic cyclic variations of their parameters, we consider discrete versions of adiabatically-rotated rotators. Parallelling the studies in continuous systems, we generalize the concept ...

Elsevier Science Bv2016

The collisional depolarization of OH(A (2)Sigma(+)) and NO(A (2)Sigma(+)) with Kr

Quantum beat spectroscopy has been used to measure rate coefficients at 300 K for collisional depolarization for NO(A (2)Sigma(+)) and OH(A (2)Sigma(+)) with krypton. Elastic depolarization rate coefficients have also been determined for OH(A) + Kr, and sh ...

Amer Inst Physics2014

Berry phase investigation of spin-S ladders

Frédéric Mila, Natalia Chepiga, Frédéric Alexis Michaud

We investigate the properties of antiferromagnetic spin-S ladders with the help of local Berry phases defined by imposing a twist on one or a few local bonds. In gapped systems with time-reversal symmetry, these Berry phases are quantized, hence able in pr ...

2013

Ab initio-driven trajectory-based nuclear quantum dynamics in phase space

Ivano Tavernelli

We derive a Bohmian trajectory-based quantum dynamics approach for the calculation of adiabatic and nonadiabatic quantum effects in ab initio on-the-fly molecular dynamics simulations. The method is designed for calculations in the full, unconstrained, pha ...

Amer Physical Soc2013

Measuring nonadiabaticity of molecular quantum dynamics with quantum fidelity and with its efficient semiclassical approximation

Jiri Vanicek, Tomas Zimmermann

We propose to measure nonadiabaticity of molecular quantum dynamics rigorously with the quantum fidelity between the Born-Oppenheimer and fully nonadiabatic dynamics. It is shown that this measure of nonadiabaticity applies in situations where other criter ...

American Institute of Physics2012

Adiabatic Passage of Light in CMOS-Compatible Silicon Oxide Integrated Rib Waveguides

Victor Javier Cadarso Busto

A fully complementary metal-oxide-semiconductor-compatible adiabatic passage of light in the visible range is presented in this letter. We experimentally show that a system of three total internal reflection waveguides, which has been defined by using non- ...

2012

Nonadiabatic Molecular Dynamics with Solvent Effects: a LR-TDDFT QM/MM Study of Ruthenium (II) Tris(bipyridine) in Water

Ursula Röthlisberger, Ivano Tavernelli, Basile Curchod

The previously derived trajectory-based nonadiabatic molecular dynamics scheme [E. Tapavicza, I. Tavernelli, U. Rothlisberger, Phys. Rev. Lett. 98 (2007) 023001] is extended to include the coupling of the quantum system with a classically described environ ...

Elsevier2011

Berry phase and pseudospin winding number in bilayer graphene

Nicola Marzari

Ever since the novel quantum Hall effect in bilayer graphene was discovered, and explained by a Berry phase of 2 pi [K. S. Novoselov et al., Nat. Phys. 2, 177 (2006)], it has been widely accepted that the low-energy electronic wave function in this system ...

2011

Non-adiabatic coupling vectors within linear response time-dependent density functional theory

Ursula Röthlisberger, Ivano Tavernelli, Enrico Marko Tapavicza

A method is developed to compute the nonadiabatic coupling vectors (NACVs) between electronic ground and excited states as well as between any possible pair of excited states within the framework of linear response time-dependent density functional theory ...

2009

Ammonia two-phase flow in a horizontal smooth tube: Flow pattern observations, diabatic and adiabatic frictional pressure drops and assessment of prediction methods

John Richard Thome, Jesus Moreno Quiben, Ricardo Lima

The present study illustrates new experimental two-phase flow pattern observations together with diabatic boiling and adiabatic two-phase frictional pressure drop results for ammonia (R7117) flowing inside a 14-mm internal diameter, smooth horizontal stain ...

2009

Role of nonadiabatic untrapped electrons in global electrostatic ion temperature gradient driven modes in a tokamak

Laurent Villard, Stephan Brunner, Paolo Angelino

In this work, role of nonadiabatic untrapped electrons in the context of a global ion temperature gradient driven mode has been investigated. In past studies, untrapped electrons have been assumed to be able to respond "instantaneously" to a disturbance. I ...

American Institute of Physics2008