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A reason is discussed (may be not the only one) for why we do not see any superposition of macroscopic states in the real world. Under the general assumption that quantum macrostates are statistical ensembles of microstates, it is shown…

Quantum Physics · Physics 2026-05-18 Fabio Siringo

Macroscopic quantum superpositions, such as mechanical Schr\"odinger cat states, are central to emerging quantum technologies in sensing and bosonic error-correcting codes. We propose a scheme to generate such states by coupling a…

Quantum Physics · Physics 2026-01-26 M. Tahir Naseem

We present a method for preparing various exotic modifications of Schr{\"o}dinger cat states by coupling a semiclassical oscillator to a system of qubits. Varying the number of qubits and parameters of the protocol (involving quantum quench…

Quantum Physics · Physics 2026-04-01 Pavel Stránský , Pavel Cejnar

We discuss several methods to produce superpositions of optical coherent states (also known as "cat states"). Cat states have remarkable properties that could allow them to be powerful tools for quantum information processing and metrology.…

Quantum Physics · Physics 2009-11-13 S. Glancy , H. M. Vasconcelos

We propose an optical scheme to generate a superposition of coherent states with enhanced size adopting an interferometric setting at the single-photon level currently available in the laboratory. Our scheme employs a nondegenerate optical…

Quantum Physics · Physics 2012-06-19 Chang-Woo Lee , Jinhyoung Lee , Hyunchul Nha , Hyunseok Jeong

We discuss the idea that superpositions in quantum mechanics may involve contradictions or contradictory properties. A state of superposition such as the one comprised in the famous Schr\"odinger's cat, for instance, is sometimes said to…

Quantum Physics · Physics 2014-06-10 Jonas R. B. Arenhart , Décio Krause

Schr\"{o}dinger cat states, consisting of superpositions of macroscopically distinct states, provide key resources for a large number of emerging quantum technologies in quantum information processing. Here we propose how to generate and…

Quantum Physics · Physics 2022-06-14 Baijun Li , Wei Qin , Ya-Feng Jiao , Cui-Lu Zhai , Xun-Wei Xu , Le-Man Kuang , Hui Jing

Optical Schrodinger's cat (SC) is highly anticipated because of the potential of realizing fault-tolerant quantum computing, but the practical merit is only shown when the amplitude is larger than 2. However, such high-amplitude cats have…

Quantum Physics · Physics 2024-07-04 Nuo Wang , Xinchen Zhang , Qi Liu , Fengxiao Sun , Qiongyi He , Ying Gu

Given a source of two coherent state superpositions with small separation in a traveling wave optical setting, we show that by interference and balanced homodyne measurement it is possible to conditionally prepare a symmetrically placed…

Quantum Physics · Physics 2015-11-23 P. Adam , T. Kiss , Z. Darázs , I. Jex

By comparing Schr\"odinger's cat with its classical counterpart, I show that a quantum superposition should be understood as an expectation over possible eigenstates weighted by wave-like probabilities. Upon the occurrence of a certain…

Quantum Physics · Physics 2025-11-07 Yanting Wang

We report on the experimental observation of quantum-network-compatible light described by a non-positive Wigner function. The state is generated by photon subtraction from a squeezed vacuum state produced by a continuous wave optical…

Quantum Physics · Physics 2007-05-23 J. S. Neergaard-Nielsen , B. Melholt Nielsen , C. Hettich , K. Moelmer , E. S. Polzik

The most striking feature of quantum mechanics is the existence of superposition states, where an object appears to be in different situations at the same time. The existence of such states has been tested with small objects, like atoms,…

Quantum Physics · Physics 2010-04-14 Oriol Romero-Isart , Mathieu L. Juan , Romain Quidant , J. Ignacio Cirac

We outline a toolbox comprised of passive optical elements, single photon detection and superpositions of coherent states (Schrodinger cat states). Such a toolbox is a powerful collection of primitives for quantum information processing…

Quantum Physics · Physics 2009-11-10 A. Gilchrist , Kae Nemoto , W. J. Munro , T. C. Ralph , S. Glancy , Samuel. L. Braunstein , G. J. Milburn

Quantum superpositions of coherent states are produced both in microwave and optical domains, and are considered realizations of the famous "Schr\"odinger cat" state. The recent progress shows an increase in the number of components and the…

Quantum Physics · Physics 2019-08-08 D. B. Horoshko , G. Patera , M. I. Kolobov

The basic idea here is that observation (or one's experience) is fundamental and the `atomic world' is postulated as the source of such observation. Once this source has been inferred to exist one may attempt to explicitly derive its…

Quantum Physics · Physics 2022-09-28 Matthew F. Brown

In this paper we re-investigate the core of Schroedinger's 'cat paradox'. We argue that one has to distinguish clearly between superpositions of macroscopic cat states and superpositions of entangled states which comprise both the state of…

Quantum Physics · Physics 2009-11-13 S. Rinner , E. Werner

The entangled "Schrodinger's cat state" of a quantum and its measurement apparatus is not a paradoxical superposition of states but is instead a non-paradoxical superposition of nonlocal coherent correlations between states: An un-decayed…

Quantum Physics · Physics 2022-06-14 Art Hobson

Quantum superpositions of macroscopically distinct classical states, so-called Schr\"{o}dinger cat states, are a resource for quantum metrology, quantum communication, and quantum computation. In particular, the superpositions of two…

We propose a scheme to create a macroscopic ``Sch\"odinger cat'' state formed by two interacting Bose condensates. In analogy with quantum optics, where the control and engineering of quantum states can be maintained to a large extend, we…

Quantum Physics · Physics 2009-10-30 J. I. Cirac , M. Lewenstein , K. Moelmer , P. Zoller

The superposition principle is one of the landmarks of quantum mechanics. The importance of quantum superpositions provokes questions about the limitations that quantum mechanics itself imposes on the possibility of their generation. In…

Quantum Physics · Physics 2016-03-23 Michał Oszmaniec , Andrzej Grudka , Michał Horodecki , Antoni Wójcik