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Complex and spinorial techniques of general relativity are used to determine all the states of the $SU(2)$ invariant quantum mechanical systems in which the equality holds in the uncertainty relations for the components of the angular…

General Relativity and Quantum Cosmology · Physics 2023-03-10 László B. Szabados

The monitoring of the three independent components of the angular momentum (or spin) of a quantum system by its environment that does not isolate any preferred orientation is modelled in two different ways. One describes the dynamics by the…

Quantum Physics · Physics 2026-05-05 Dorje C. Brody , Eva-Maria Graefe , Rishindra Melanathuru

Versatile and high-brightness sources of high-dimensional entangled photon pairs are important for emerging quantum technologies such as secure quantum communication. Here, we experimentally demonstrate a new scalable method to create…

Quantum Physics · Physics 2020-10-28 Jaroslav Kysela , Manuel Erhard , Armin Hochrainer , Mario Krenn , Anton Zeilinger

We present a new type of energy-momentum tensor and angular momentum tensor. They are motivated by a special consideration in quantum measurement: Given a wave in mutual eigen-state of more than one physical observables, the corresponding…

General Physics · Physics 2017-01-31 Zhen-Lai Wang , De-Tian Yang , Zi-Wei Chen , Tao Lei , Xiang-Song Chen

We first review and critically examine some basic concepts and ambiguities related to quantum mechanics and quantum measurement to understand the success and shortcomings of current theories. We also touch on ideas regarding expression of…

Quantum Physics · Physics 2009-11-05 Fariel Shafee

The notion of the quantum angle is introduced. The quantum angle turns out to be a metric on the set of physical states of a quantum system. Its kinematics and dynamics is studied. The certainty principle for quantum systems is formulated…

Quantum Physics · Physics 2007-05-23 D. A. Arbatsky

We establish a mapping between a continuous variable (CV) quantum system and a discrete quantum system of arbitrary dimension. This opens up the general possibility to perform any quantum information task with a CV system as if it were a…

Quantum Physics · Physics 2009-11-07 Caslav Brukner , Myungshik S. Kim , Jian-Wei Pan , Anton Zeilinger

So far experimental confirmation of entanglement has been restricted to qubits, i.e. two-state quantum systems including recent realization of three- and four-qubit entanglements. Yet, an ever increasing body of theoretical work calls for…

Quantum Physics · Physics 2009-11-07 Alois Mair , Alipasha Vaziri , Gregor Weihs , Anton Zeilinger

We derive simple practical procedures revealing the quantum behavior of angular momentum variables by the violation of classical upper bounds on the statistics. Data analysis is minimum and definite conclusions are obtained without…

Quantum Physics · Physics 2011-12-06 Alfredo Luis , Ángel Rivas

Quantum annealing is a generic algorithm using quantum-mechanical fluctuations to search for the solution of an optimization problem. The present paper first reviews the fundamentals of quantum annealing and then reports on preliminary…

Disordered Systems and Neural Networks · Physics 2010-06-10 Masayuki Ohzeki , Hidetoshi Nishimori

The uncertainty principle places a fundamental limit on the accuracy with which we can measure conjugate physical quantities. However, the fluctuations of these variables can be assessed in terms of different estimators. We propose a new…

Quantum Physics · Physics 2010-05-10 Z. Hradil , J. Rehacek , A. B. Klimov , I. Rigas , L. L. Sanchez-Soto

We address the possibility of using even/odd states of orbital angular momentum (OAM) of photons for the quantum information tasks. Single photon qubit states and two photon entangled states in even/odd basis of OAM are considered. We…

Quantum Physics · Physics 2017-05-24 Chithrabhanu Perumangatt , Nijil Lal , Ali Anwar , Salla Gangi Reddy , R. P. Singh

We argue that in contrast to the classical physics, the measurements in the quantum mechanics should provide simultaneous information about all relevant relative amplitudes (pure states and the transitions between them) and all relevant…

Quantum Physics · Physics 2009-06-23 Daniel Sepunaru , Uzi Notev

An analysis of quantum measurement is presented that relies on an information-theoretic description of quantum entanglement. In a consistent quantum information theory of entanglement, entropies (uncertainties) conditional on measurement…

Quantum Physics · Physics 2008-02-03 N. J. Cerf , C. Adami

We develop an original approach for the quantitative characterisation of the entanglement properties of, possibly mixed, bi- and multipartite quantum states of arbitrary finite dimension. Particular emphasis is given to the derivation of…

Quantum Physics · Physics 2009-11-11 Florian Mintert , Andre R. R. Carvalho , Marek Kus , Andreas Buchleitner

Photons with a twisted phase front carry a quantized amount of orbital angular momentum (OAM) and have become important in various fields of optics, such as quantum and classical information science or optical tweezers. Because no upper…

Quantum Physics · Physics 2016-11-21 Robert Fickler , Geoff T. Campbell , Ben C. Buchler , Ping Koy Lam , Anton Zeilinger

We consider the problem of a state determination for a two-level quantum system which can be in one of two nonorthogonal mixed states. It is proved that for the two independent identical systems the optimal combined measurement (which…

Quantum Physics · Physics 2007-05-23 A. E. Allahverdyan , D. B. Saakian

The violation of local uncertainty relations is a valuable tool for detecting entanglement, especially in multi-dimensional systems. The orbital angular momentum of light provides such a multi-dimensional system. We study quantum…

Quantum Physics · Physics 2007-05-23 Joerg B Goette , Sonja Franke-Arnold , Stephen M. Barnett

Quantum tomography is a method to experimentally extract all that is observable about a quantum mechanical system. We introduce quantum tomography to collider physics with the illustration of the angular distribution of lepton pairs. The…

High Energy Physics - Phenomenology · Physics 2018-01-17 John C. Martens , John P. Ralston , J. D. Tapia Takaki

Accurately estimating properties of quantum states, such as entanglement, while essential for the development of quantum technologies, remains a challenging task. Standard approaches to property estimation rely on detailed modeling of the…