Publications related to Imaginary unit

SPEEDING UP KRYLOV SUBSPACE METHODS FOR COMPUTING f(A)b VIA RANDOMIZATION

This work is concerned with the computation of the action of a matrix function f(A), such as the matrix exponential or the matrix square root, on a vector b. For a general matrix A, this can be done by computing the compression of A onto a suitable Krylov ...

Siam Publications2024

Asymmetric phase modulation of light with parity-symmetry broken metasurfaces

Karim Achouri, Jean-Yves Duboz

The design of wavefront-shaping devices is conventionally approached using real-frequency modeling. However, since these devices interact with light through radiative channels, they are by default non-Hermitian objects having complex eigenvalues (poles and ...

Optica Publishing Group2023

Nonperturbative aspects of scattering amplitudes

Miguel Alexandre Ribeiro Correia

In this thesis we study how physical principles imposed on the S-matrix, such as Lorentz invariance, unitarity, crossing symmetry and analyticity constrain quantum field theories at the nonperturbative level. We start with a pedagogical introduction to the ...

EPFL2023

Quand les artistes font forme en habitant ensemble. Usages, présences, imaginaires

Mathilde Coline Chénin

Taking root within a historical and transversal perspective of communities of artists at work, and of the relationship that they nourish with the places that host their creative activity, the present research intends to bring to light the grammars of "the ...

EPFL2022

Systems and methods for energy-efficient measurement of neurophysiological oscillations

Mahsa Shoaran, Uisub Shin

A system for measuring synchrony between two or more regions, or within a single region, of a subject's brain. The system can include a signal conditioning module in communication with a phase extraction module. The signal conditioning module can receive a ...

2022

A finiteness result for p-adic families of Bianchi modular forms

Vlad Serban

We study p-adic families of cohomological automorphic forms for GL(2) over imaginary quadratic fields and prove that families interpolating a Zariski-dense set of classical cuspidal automorphic forms only occur under very restrictive conditions. We show ho ...

ACADEMIC PRESS INC ELSEVIER SCIENCE2022

TimeEvolver: A program for time evolution with improved error bound

Sebastian Zell

We present TimeEvolver, a program for computing time evolution in a generic quantum system. It relies on well-known Krylov subspace techniques to tackle the problem of multiplying the exponential of a large sparse matrix iH, where His the Hamiltonian, with ...

ELSEVIER2022

Apparent diffusion coefficient measured by diffusion MRI of moving and deforming domains

Jan Sickmann Hesthaven

The modeling of the diffusion MRI signal from moving and deforming organs such as the heart is challenging due to significant motion and deformation of the imaged medium during the signal acquisition. Recently, a mathematical formulation of the Bloch-Torre ...

Academic Press Inc - Elsevier Science2020

Realtime: making digital China

Realtime is an investigation about china’s digital and urban infrastructure, practices and imaginary spaces. Realtime attempts to capture the pace, scale and depth of china’s complex and changing reality. ...

EPFL Press2020

Standard-Model Prediction of epsilon(K) with Manifest Quark-Mixing Unitarity

Emmanuel Stamou

The parameter epsilon(K) describes CP violation in the neutral kaon system and is one of the most sensitive probes of new physics. The large uncertainties related to the charm-quark contribution to epsilon(K) have so far prevented a reliable standard-model ...

AMER PHYSICAL SOC2020

Loss of transverse Landau damping by noise and wakefield driven diffusion

Xavier Buffat, Sondre Vik Furuseth

Landau damping of coherent modes is strongly dependent on the exact shape of the particle bunches. One often assumes that the transverse distributions in high-energy hadron colliders can be approximated by Gaussian distributions, in acceptable agreement wi ...

2020

Robustness of Yu-Shiba-Rusinov resonances in the presence of a complex superconducting order parameter

Klaus Kern, Markus Etzkorn, Jacob Senkpiel

Robust quantum systems rely on having a protective environment with minimized relaxation channels. Super-conducting gaps play an important role in the design of such environments. The interaction of localized single spins with a conventional superconductor ...

AMER PHYSICAL SOC2019

Complex magnetoelectric effect in multiferroic composites: the case of PFN- PT/(Co,Ni)Fe2O4

Hadi Papi, Hossein Ahmadvand

We report a systematic study of the magnetoelectric (ME) voltage coefficient as a complex quantity in the particulate composite of ferroelectric solid solution 0.94Pb(Fe1/2N1/2)O-3-0.06PbTiO(3)(PFN-PT) with CoFe2O4(CFO) and NiFe2O4 (NFO) ferrites. The resu ...

2019

5 GHz laterally-excited bulk-wave resonators (XBARs) based on thin platelets of lithium niobate

Luis Guillermo Villanueva Torrijo, Soumya Yandrapalli, Victor Plessky

In a free-standing 400-nm-thick platelet of crystalline ZY-LiNbO3, narrow electrodes (500 nm) placed periodically with a pitch of a few microns can eXcite standing shear-wave bulk acoustic resonances (XBARs), by utilising lateral electric fields oriented p ...

2019

Efficient Verifiable Delay Functions

Benjamin Pierre Charles Wesolowski

We construct a verifiable delay function (VDF). A VDF is a function whose evaluation requires running a given number of sequential steps, yet the result can be efficiently verified. They have applications in decentralised systems, such as the generation of ...

SPRINGER INTERNATIONAL PUBLISHING AG2019

Automobility Beyond Car : Introducing a New Coordinate System for Transforming Urban Mobility

Farzaneh Bahrami

How is the future of automobility imagined today? What has structured such imaginary ? And what levers can steer its evolution towards a Post-Car World? These very three questions form the foundational motivations of this thesis. First, through a h ...

EPFL2017

A gauge invariant Debye mass and the complex heavy-quark potential

Yannis Burnier

Following the original idea of Debye, we define and extract a gauge-invariant screening mass from the complex static in-medium heavy-quark potential V-Q (Q) over bar, recently obtained from lattice QCD. To this end we derive a formula using concepts from b ...

Elsevier2016

Low-energy biomarker detection through charge-based impedance measurements

Mihai Adrian Ionescu, Junrui Zhang, Marco Mazza

A novel approach for the detection of biomarkers in aqueous condition via differential impedance is presented. The binding of biomarkers onto functionalized inter-digital electrodes induces a change in the sensor impedance, both in its real and imaginary c ...

2016

The Bayesian reconstruction of the in-medium heavy quark potential from lattice QCD and its stability

Yannis Burnier

We report recent results of a non-perturbative determination of the static heavy-quark potential in quenched and dynamical lattice QCD at finite temperature. The real and imaginary part of this complex quantity are extracted from the spectral function of W ...

Amer Inst Physics2016

Low rank differential equations for Hamiltonian matrix nearness problems

Daniel Kressner

For a Hamiltonian matrix with purely imaginary eigenvalues, we aim to determine the nearest Hamiltonian matrix such that some or all eigenvalues leave the imaginary axis. Conversely, for a Hamiltonian matrix with all eigenvalues lying off the imaginary axi ...

Springer2015