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We formulate entropic measurements uncertainty relations (MURs) for a spin-1/2 system. When incompatible observables are approximatively jointly measured, we use relative entropy to quantify the information lost in approximation and we…

Quantum Physics · Physics 2018-05-11 Alberto Barchielli , Matteo Gregoratti

A comprehensive uncertainty estimation is vital for the precision program of the LHC. While experimental uncertainties are often described by stochastic processes and well-defined nuisance parameters, theoretical uncertainties lack such a…

High Energy Physics - Phenomenology · Physics 2023-05-08 Aishik Ghosh , Benjamin Nachman , Tilman Plehn , Lily Shire , Tim M. P. Tait , Daniel Whiteson

The uncertainty principle is often interpreted by the tradeoff between the error of a measurement and the consequential disturbance to the followed ones, which originated long ago from Heisenberg himself but now falls into reexamination and…

Quantum Physics · Physics 2018-03-29 Yu-Xiang Zhang , Shengjun Wu , Zeng-Bing Chen

The uncertainty principle lies at the heart of quantum physics, and is widely thought of as a fundamental limit on the measurement precisions of incompatible observables. Here we show that the traditional uncertainty relation in fact…

Quantum Physics · Physics 2021-02-03 Jun-Li Li , Cong-Feng Qiao

The existence of \emph{weak conical K\"ahler-Einstein} metrics along smooth hypersurfaces with angle between $0$ and $2\pi$ is obtained by studying a smooth continuity method and a \emph{local Moser's iteration} technique. In the case of…

Differential Geometry · Mathematics 2013-08-21 Chengjian Yao

The intrinsic fluctuations of electron spins in semiconductors and atomic vapors generate a small, randomly-varying "spin noise" that can be detected by sensitive optical methods such as Faraday rotation. Recent studies have demonstrated…

In principle particle spins can be measured from their production cross sections once their mass is approximately known. The method works in practice because spins are quantized and cross sections depend strongly on spins. It can be used to…

High Energy Physics - Phenomenology · Physics 2010-03-02 Gordon L. Kane , Alexey A. Petrov , Jing Shao , Lian-Tao Wang

The squares of the three components of the spin-s operators sum up to $s(s+1)$. However, a similar relation is rarely satisfied by the set of possible spin projections onto mutually orthogonal directions. This has fundamental consequences…

Algorithms for finding arbitrary sets of Kochen-Specker (KS) qunits (n-level systems) as well as all the remaining vectors in a space of an arbitrary dimension are presented. The algorithms are based on linear MMP diagrams which generate…

Quantum Physics · Physics 2015-06-26 Mladen Pavicic

Several communication models that are of relevance in practice are asymmetric in the way they act on the transmitted "objects". Examples include channels in which the amplitudes of the transmitted pulses can only be decreased, channels in…

Information Theory · Computer Science 2022-12-29 Mladen Kovačević , Dejan Vukobratović

Uncertainty relations give upper bounds on the accuracy by which the outcomes of two incompatible measurements can be predicted. While established uncertainty relations apply to cases where the predictions are based on purely classical data…

Quantum Physics · Physics 2012-10-18 Marco Tomamichel , Renato Renner

We performed an experimental test of the Kochen-Specker theorem based on an inequality derived from the Peres-Mermin proof, using spin-path (momentum) entanglement in a single neutron system. Following the strategy proposed by Cabello et…

Quantum Physics · Physics 2009-07-28 H. Bartosik , J. Klepp , C. Schmitzer , S. Sponar , A. Cabello , H. Rauch , Y. Hasegawa

Using a quantum like algebraic formulation we give proof of Kochen-Specker theorem. We introduce new criteria in order to account for the contextual nature of measurements in quantum mechanics.

General Physics · Physics 2007-12-19 Elio Conte

Coherent states provide an appealing method to reconstruct efficiently a pure state of a quantum mechanical spin s. A Stern-Gerlach apparatus is used to measure (4s+1) expectations of projection operators on appropriate coherent states in…

Quantum Physics · Physics 2007-05-23 Jean-Pierre Amiet , Stefan Weigert

Klyachko and coworkers consider an orthogonality graph in the form of a pentagram, and in this way derive a Kochen-Specker inequality for spin 1 systems. In some low-dimensional situations Hilbert spaces are naturally organised, by a…

Quantum Physics · Physics 2022-03-16 Piotr Badziag , Ingemar Bengtsson , Adan Cabello , Helena Granstrom , Jan-Åke Larsson

We demonstrate that the location of a stable photon sphere (PS) in a compact object is not always an edge such as the inner boundary of a black hole shadow, whereas the location of an unstable PS is known to be the shadow edge notably in…

General Relativity and Quantum Cosmology · Physics 2022-06-08 Ryuya Kudo , Hideki Asada

We examine the problem of estimating the expectation values of two observables when we have a finite number of copies of an unknown qubit state. Specifically we examine whether it is better to measure each of the observables separately on…

Quantum Physics · Physics 2009-11-13 Thomas Brougham , Erika Andersson

On a quantum particle in the unit interval $[0,1]$, perform a position measurement with inaccuracy $1/n$ and then a quantum measurement of the projection $|\phi\rangle\langle\phi|$ with some arbitrary but fixed normalized $\phi$. Call the…

Quantum Physics · Physics 2026-02-26 Xabier Oianguren-Asua , Roderich Tumulka

The Kochen-Specker theorem rules out models of quantum theory wherein projective measurements are assigned outcomes deterministically and independently of context. This notion of noncontextuality is not applicable to experimental…

Quantum Physics · Physics 2018-05-11 Ravi Kunjwal , Robert W. Spekkens

The Schr{\"o}dinger inequality is known to underlie the Kennard-Robertson inequality, which is the standard expression of quantum uncertainty for the product of variances of two observables $A$ and $B$, in the sense that the latter is…

Quantum Physics · Physics 2020-08-10 Jaeha Lee , Keita Takeuchi , Kaisei Watanabe , Izumi Tsutsui