Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1202.0631 · New Journal of Physics

Quantum Cheshire Cats

Yakir Aharonov, Sandu Popescu, Daniel Rohrlich, Paul Skrzypczyk

Published Nov 7, 2013• 194 citations
arXivHTMLPDF

Abstract

In this paper we present a quantum Cheshire Cat. In a pre- and post-selected experiment we find the Cat in one place, and its grin in another. The Cat is a photon, while the grin is its circular polarization.
DOI
10.1088/1367-2630/15/11/113015

Related papers

Quantum Cheshire Cats

Sandu Popescu, Aharonov, Y, Rohrlich, D +1 more

In this paper we present a quantum Cheshire Cat. In a pre- and post-selected experiment we find the Cat in one place, and its grin in another. The Cat is a photon, while the grin is its circular polarization.

•Nov 7, 2013•0 citations

‘Quantum Cheshire Cat’ as simple quantum interference

Raul Corrêa, Marcelo França Santos, Carlos Henrique Monken +1 more

In a recent work, Aharonov et al suggested that a photon could be separated from its polarization in an experiment involving pre- and post-selection (Aharonov et al 2013 New J. Phys. 15 113015 ). They named the effect 'quantum Cheshire Cat', in a reference to the cat that is separated from its grin in the novel Alice ' s Adventures in Wonderland . Following these ideas, Denkmayr et al performed a neutron interferometric experiment and interpreted the results suggesting that neutrons were separated from their spin (Denkmayr et al 2014 Nat. Commun. 5 4492 ). Here we show that these results can be interpreted as simple quantum interference, with no separation between the quantum particle and its internal degree of freedom. We thus hope to clarify the phenomenon with this work, by removing these apparent paradoxes.

arXiv:1409.0808•New Journal of Physics•May 27, 2015•45 citations

Twin Quantum Cheshire Photons

Issam Ibnouhsein, Alexei Grinbaum

In an experiment with both pre- and post-selection one can find a photon (the cat) in one place and its polarization (the smile) in another. Aharonov et al. asked recently whether more than two degrees of freedom could be separated in the same way. We show that this is possible and that the separation of properties from objects that carry them is in some situations even stronger.

arXiv:1202.4894•Feb 22, 2012•5 citations

O Gato de Cheshire quântico como um fenômeno de interferência

Raul Correa Silva

Based on the concept of weak measurements, in 2013 Aharonov et al. proposed an experiment in which, according to their interpretation of the predicted results, a photon and its circular polarization were spatially separated, naming this phenomenon quantum Cheshire Cat [1]. This name is after a character in Lewis Carrolls novel Alice In Wonderland, the Cheshire Cat a cat whose grin can exist without the animal itself. Denkmayr et al., in 2014, claimed they realized experimentally the quantum Cheshire Cat, separating a neutron from its intrinsic magnetic moment [3]. We show how both results follow from interference effects, and thus the conclusion that a particle is separated from one of its intrinsic properties is not a necessary one. Making use of mostly undergraduate level quantum mechanics, we rule out the apparent paradox of the quantum Cheshire Cat.

•Feb 25, 2015•0 citations

The Complete Quantum Cheshire Cat

Yelena Guryanova, Nicolas Brunner, Sandu Popescu

We show that a physical property can be entirely separated from the object it belongs to, hence realizing a complete quantum Cheshire cat. Our setup makes use of a type of quantum state of particular interest, namely an entangled pre- and post-selected state, in which the pre- and post-selections are entangled with each other. Finally we propose a scheme for the experimental implementation of these ideas.

arXiv:1203.4215•Mar 19, 2012•7 citations

Can two quantum Cheshire cats exchange grins?

Debmalya Das, Arun Kumar Pati

Abstract A common-sense perception of a physical system is that it is inseparable from its physical properties. The notion of quantum Cheshire cat challenges this, as far as quantum systems are concerned. It shows that a quantum system can be decoupled from its physical property under suitable pre and postselections. However, in the quantum Cheshire cat setup, the decoupling is not permanent. The photon, for example, and its circular polarization is separated and then recombined. In this paper, we present a thought experiment where we decouple two photons from their respective polarizations and then interchange them during recombination. Thus, our proposal shows that that the belongingness of a property for a physical system is very volatile in the quantum world. This raises the question of reality of an observable at a much deeper level.

arXiv:1904.07707•New Journal of Physics•Apr 29, 2020•24 citations
In a recent work, Aharonov et al suggested that a photon could be separated from its polarization in an experiment involving pre- and post-selection (Aharonov et al 2013 New J. Phys. 15 113015 ). They named the effect 'quantum Cheshire Cat', in a reference to the cat that is separated from its grin in the novel Alice ' s Adventures in Wonderland . Following these ideas, Denkmayr et al performed a neutron interferometric experiment and interpreted the results suggesting that neutrons were separated from their spin (Denkmayr et al 2014 Nat. Commun. 5 4492 ). Here we show that these results can be interpreted as simple quantum interference, with no separation between the quantum particle and its internal degree of freedom. We thus hope to clarify the phenomenon with this work, by removing these apparent paradoxes.
Based on the concept of weak measurements, in 2013 Aharonov et al. proposed an experiment in which, according to their interpretation of the predicted results, a photon and its circular polarization were spatially separated, naming this phenomenon quantum Cheshire Cat [1]. This name is after a character in Lewis Carrolls novel Alice In Wonderland, the Cheshire Cat a cat whose grin can exist without the animal itself. Denkmayr et al., in 2014, claimed they realized experimentally the quantum Cheshire Cat, separating a neutron from its intrinsic magnetic moment [3]. We show how both results follow from interference effects, and thus the conclusion that a particle is separated from one of its intrinsic properties is not a necessary one. Making use of mostly undergraduate level quantum mechanics, we rule out the apparent paradox of the quantum Cheshire Cat.
Abstract A common-sense perception of a physical system is that it is inseparable from its physical properties. The notion of quantum Cheshire cat challenges this, as far as quantum systems are concerned. It shows that a quantum system can be decoupled from its physical property under suitable pre and postselections. However, in the quantum Cheshire cat setup, the decoupling is not permanent. The photon, for example, and its circular polarization is separated and then recombined. In this paper, we present a thought experiment where we decouple two photons from their respective polarizations and then interchange them during recombination. Thus, our proposal shows that that the belongingness of a property for a physical system is very volatile in the quantum world. This raises the question of reality of an observable at a much deeper level.