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We investigate the presence of spin- and planar- squeezing in generalized superpositions of atomic (or spin) coherent states (ACS). Spin-squeezing has been shown to be a useful tool in determining the presence of entanglement in…

Quantum superposition is often phrased as the ability to add state vectors. In practice, however, the physical quantity is a ray (a rank-one projector), so each input specifies only a projector and leaves a gauge freedom in the phases of…

Quantum Physics · Physics 2026-01-22 Jeongho Bang , Kyoungho Cho , Ki Hyuk Yee

The entanglement of superpositions [Phys. Rev. Lett. 97, 100502 (2006)] is generalized to the multipartite scenario: an upper bound to the multipartite entanglement of a superposition is given in terms of the entanglement of the superposed…

Quantum Physics · Physics 2007-10-24 D. Cavalcanti , M. O. Terra Cunha , A. Acin

The quantum superposition principle is reexamined and reformulated based on the adiabatic theorem of quantum mechanics, nonadiabatic dressed states and experimental evidences. The collapse of the wave function and the quantum measurement…

General Physics · Physics 2025-05-14 I. G. Koprinkov

Clarifying the nature of the quantum state $|\Psi\rangle$ is at the root of the problems with insight into counter-intuitive quantum postulates. We provide a direct-and math-axiom free-empirical derivation of this object as an element of a…

Quantum Physics · Physics 2022-04-14 Yurii V. Brezhnev

The superposition principle lies at the heart of many non-classical properties of quantum mechanics. Motivated by this, we introduce a rigorous resource theory framework for the quantification of superposition of a finite number of linear…

Quantum Physics · Physics 2017-12-19 T. Theurer , N. Killoran , D. Egloff , M. B. Plenio

One of the peculiar features in quantum mechanics is that a superposition of macroscopically distinct states can exits. In optical system, this is highlighted by a superposition of coherent states (SCS), i.e. a superposition of classical…

Quantum Physics · Physics 2018-02-19 Shuro Izumi , Masahiro Takeoka , Kentaro Wakui , Mikio Fujiwara , Kazuhiro Ema , Masahide Sasaki

Superposition, arguably the most fundamental property of quantum mechanics, lies at the heart of quantum information science. However, how to create the superposition of any two unknown pure states remains as a daunting challenge. Recently,…

Quantum Physics · Physics 2017-03-10 Keren Li , Guofei Long , Hemant Katiyar , Tao Xin , Guanru Feng , Dawei Lu , Raymond Laflamme

Consider minimizing the entropy of a mixture of states by choosing each state subject to constraints. If the spectrum of each state is fixed, we expect that in order to reduce the entropy of the mixture, we should make the states less…

Quantum Physics · Physics 2024-04-30 Mohammad A. Alhejji , Emanuel Knill

The superposition principle is at the heart of quantum mechanics and at the root of many paradoxes arising when trying to extend its predictions to our everyday world. Schroedinger's cat is the prototype of such paradoxes and here, in…

We propose an experimentally accessible, objective measure for the macroscopicity of superposition states in mechanical quantum systems. Based on the observable consequences of a minimal, macrorealist extension of quantum mechanics, it…

Quantum Physics · Physics 2013-04-24 Stefan Nimmrichter , Klaus Hornberger

Quantum superposition says that any physical system simultaneously exists in all of its possible states, the number of which is exponential in the number of entities composing the system. The strength of presence of each possible state in…

Neural and Evolutionary Computing · Computer Science 2017-07-19 Gerard J. Rinkus

The evolution of a measured system and an experimental apparatus is presented in an unified form. Conditions under which the state of such a total system forms, evaluates and declines from a superposition of states are defined. The problem…

Quantum Physics · Physics 2012-09-26 Janusz Gluza , Jerzy Kosek

As it is known, neither classical logical conjunction "and" nor classical logical alternative "either...or" can replace "+" representing a linear superposition of two quantum states. Therefore, to provide a logical account of the quantum…

Quantum Physics · Physics 2017-12-19 Arkady Bolotin

Based on phase-space structures of quantum states, we propose a novel measure to quantify macroscopic quantum superpositions. Our measure simultaneously quantifies two different kinds of essential information for a given quantum state in a…

Quantum Physics · Physics 2011-06-02 Chang-Woo Lee , Hyunseok Jeong

A superposition rule is a particular type of map that enables one to express the general solution of certain systems of first-order ordinary differential equations, the so-called Lie systems, out of generic families of particular solutions…

Mathematical Physics · Physics 2011-07-14 J. F. Cariñena , J. de Lucas

The most general mathematical law for summing bounded quantities is not the arithmetic law, but a composition law of which the summation law for velocities in special relativity is only one particular example. We believe that this…

General Physics · Physics 2026-01-09 J. -M. Vigoureux

We investigate the notion of "macroscopicity" in the case of large quantum spin systems and provide two main results. First, we motivate the Fisher information as a measure for the macroscopicity of quantum states. Second, we compare the…

Quantum Physics · Physics 2012-09-28 Florian Fröwis , Wolfgang Dür

A ubiquitous feature of quantum mechanical theories is the existence of states of superposition. This is expected to be no different for a quantum gravity theory. Guided by this consideration and others we consider a framework in which…

Quantum Physics · Physics 2023-12-22 Elliott Tammaro , Hunter Angle , Edmund Mbadu

We prove that the vast majority of symmetric states of qubits can be decomposed in a unique way into a superposition of spin 1/2 coherent states. For the case of two qubits, the proposed decomposition reproduces the Schmidt decomposition…

Quantum Physics · Physics 2015-06-25 A. Mandilara , T. Coudreau , A. Keller , P. Milman