# Can Two Quantum Cheshire Cats Exchange Grins?

## TL;DR

This paper explores the transient and exchangeable nature of quantum properties in a thought experiment involving two photons, challenging the notion of fixed properties in quantum systems.

## Contribution

It introduces a novel thought experiment demonstrating that quantum properties can be decoupled and exchanged between particles, questioning the reality of observables.

## Key findings

- Quantum properties can be temporarily decoupled from particles.
- Properties of two photons can be interchanged during recombination.
- The belongingness of properties in quantum systems is highly volatile.

## 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 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.