Publications associées à Opérateur de position

Explicit representations for Banach subspaces of Lizorkin distributions

The Lizorkin space is well suited to the study of operators like fractional Laplacians and the Radon transform. In this paper, we show that the space is unfortunately not complemented in the Schwartz space. In return, we show that it is dense in C0(Double- ...

2023

Ultra low quantum decoherence nano-optomechanical systems

Mohammadjafar Bereyhi

Thermal motion of a room-temperature mechanical resonator typically dominates the quantum backaction of its position measurement. This is a longstanding barrier for exploring cavity optomechanics at room temperature. In order to enter the quantum regime of ...

EPFL2022

Mechanical resonators with high dissipation dilution in precision and quantum measurements

Sergey Fedorov

Position measurements of mechanical oscillators underpin experiments spanning from applied nanoscale sensing to endeavors aiming to resolve open fundamental problems of modern physics. Sufficiently precise position measurements are also used for engineerin ...

EPFL2021

Fourier dimensionality reduction for fast radio transients

Jean-Philippe Thiran, Yves Wiaux, Vijay Kartik, Ming Jiang

In the context of next-generation radio interferometers, we are facing a big challenge of how to economically process data. The classical dimensionality reduction technique, averaging visibilities on time, may dilute fast radio transients (FRT). We propose ...

2019

Optical backaction-evading measurement of a mechanical oscillator

Tobias Kippenberg, Liu Qiu, Itay Shomroni

Quantum mechanics imposes a limit on the precision of a continuous position measurement of a harmonic oscillator, due to backaction arising from quantum fluctuations in the measurement field. This standard quantum limit can be surpassed by monitoring only ...

Springer2019

Quantum-Limited Measurements Using an Optical Cavity with Modulated Intrinsic Loss

Alexander Tagantsev, Sergey Fedorov

We analyze a cavity optomechanical setup, in which the position of an oscillator modulates the internal optical loss. We show that, in contrast to systems with a fixed internal loss, in such a setup, quantum-limited position measurements can be performed a ...

AMER PHYSICAL SOC2019

Detecting and Localizing Differences in Functional Time Series Dynamics: A Case Study in Molecular Biophysics

Victor Panaretos, Shahin Tavakoli

Motivated by the problem of inferring the molecular dynamics of DNA in solution, and linking them with its base-pair composition, we consider the problem of comparing the dynamics of functional time series (FTS), and of localizing any inferred differences ...

American Statistical Association2016

Quantum limits on measurement and control of a mechanical oscillator

Vivishek Sudhir

The precision measurement of position has a long-standing tradition in physics. Cavendish's verification of the universal law of gravitation using a torsion pendulum, Perrin's confirmation of the atomic hypothesis via the precise measurement of the Brownia ...

EPFL2016

Fourier Analysis of Functional Time Series, with Applications to DNA Dynamics

Shahin Tavakoli

This work is about time series of functional data (functional time series), and consists of three main parts. In the first part (Chapter 2), we develop a doubly spectral decomposition for functional time series that generalizes the Karhunen–Loève expansion ...

EPFL2014

Phase properties of operator valued measures in phase space

Vivishek Sudhir

The Wigner phase operator (WPO) is identified as an operator valued measure (OVM) and its eigenstates are obtained. An operator satisfying the canonical commutation relation with the Wigner phase operator is also constructed and this establishes a Wigner d ...

Taylor & Francis Ltd2013

Cramer-Karhunen-Loeve representation and harmonic principal component analysis of functional time series

Victor Panaretos, Shahin Tavakoli

We develop a doubly spectral representation of a stationary functional time series, and study the properties of its empirical version. The representation decomposes the time series into an integral of uncorrelated frequency components (Cramer representatio ...

Elsevier2013

Semiclassical approach to ground-state properties of hard-core bosons in two dimensions

Frédéric Mila, Tommaso Coletta, Nicolas Laflorencie

Motivated by some inconsistencies in the way quantum fluctuations are included beyond the classical treatment of hard-core bosons on a lattice in the recent literature, we revisit the large-S semiclassical approach to hard-core bosons on the square lattice ...

2012

Matrix ALPS: Accelerated Low Rank and Sparse Matrix Reconstruction

Volkan Cevher, Anastasios Kyrillidis

We propose Matrix ALPS for recovering a sparse plus low-rank decomposition of a matrix given its corrupted and incomplete linear measurements. Our approach is a first-order projected gradient method over non-convex sets, and it exploits a well-known memory ...

IEEE2012

Anomalously enhanced photoemission from the Dirac point and other peculiarities in the self-energy of the surface-state quasiparticles in Bi2Se3

Helmuth Berger

Line-shape analysis of the photoemission intensity from the surface states of Bi2Se3 reveals two unusual features: spectral line asymmetry and anomalously enhanced photoemission from the Dirac point. The former can be described by the one-particle spectral ...

2012

Full-field drift Hamiltonian particle orbits in 3D geometry

Wilfred Anthony Cooper, Jonathan Graves, Stephan Brunner

A Hamiltonian/Lagrangian theory to describe guiding centre orbit drift motion which is canonical in the Boozer coordinate frame has been extended to include full electromagnetic perturbed fields in anisotropic pressure 3D equilibria with nested magnetic fl ...

IOP2011

Resolved-sideband cooling and position measurement of a micromechanical oscillator close to the Heisenberg uncertainty limit

Tobias Kippenberg, Albert Schliesser

The theory of quantum measurement of mechanical motion, describing the mutual coupling of a meter and a measured object, predicts a variety of phenomena such as quantum backaction, quantum correlations and non-classical states of motion. In spite of great ...

2009

Mixed Wannier-Bloch functions for electrons and phonons in periodic systems

Alfredo Pasquarello

We introduce mixed Wannier-Bloch functions for studying electronic and vibrational spectra of periodic systems. These functions carry both spatial localization and limited spectral broadening, thereby combining the advantages of descriptions based on energ ...

2006

Regiochemically flexible substitutions of di-, tri-, and tetrahalopyridines: the trialkylsilyl trick

Thierry Rausis, Carla Bobbio

2,4-Difluoropyridine, 2,4-dichloropyridine, 2,4,6-trifluoropyridine, 2,4,6-trichloropyridine and 2,3,4,6-tetrafluoropyridine react with std. nucleophiles exclusively at the 4-position under halogen displacement. However, the regioselectivity can be complet ...

2005