Insider Brief
- Researchers beforehand claimed Cheshire cat-like quantum particles are in a position to separate from their properties.
- However, new work demonstrates that these experiments as a substitute show one other counterintuitive function of quantum mechanics — contextuality.
- A University of Hiroshima-led crew of researchers performed the examine, printed within the New Journal of Physics.
PRESS RELEASE — The quantum Cheshire cat impact attracts its identify from the fictional Cheshire Cat within the Alice in Wonderland story. That cat was in a position to disappear, leaving solely its grin behind. Similarly, in a 2013 paper, researchers claimed quantum particles are in a position to separate from their properties, with the properties touring alongside paths the particle can’t. They named this the quantum Cheshire cat impact. Researchers since have claimed to increase this additional, swapping disembodied properties between particles, disembodying a number of properties concurrently, and even “separating the wave-particle duality” of a particle.
However, recent analysis, printed within the New Journal of Physics, demonstrates that these experiments don’t really present particles splitting from their properties, however as a substitute show one other counterintuitive function of quantum mechanics — contextuality.
Quantum mechanics is the examine of the conduct of sunshine and matter on the atomic and subatomic scale. By its nature, quantum mechanics is counterintuitive. The analysis crew got down to basically perceive this counterintuitive nature, whereas exploring practical advantages.
“Most people know that quantum mechanics is weird, but identifying what causes this weirdness is still an active area of research. It has been slowly formalized into a notion called contextuality — that quantum systems change depending on what measurements you do on them,” mentioned Jonte Hance, a analysis fellow at Hiroshima University and the University of Bristol.
A sequence of measurements on a quantum system will produce completely different outcomes relying on the order through which the measurements are achieved. For occasion, if we measure the place a particle is, then how briskly it’s travelling, this can give completely different outcomes to first measuring how briskly it travels, then the place it’s. Because of this contextuality, quantum programs may be measured as having properties which we might count on to be mutually incompatible.
“However, we still don’t really understand what causes this, so this is what we wanted to investigate, using the paradoxical quantum Cheshire cat scenario as a testbed,” mentioned Hance.
The crew notes that the issue with the quantum Cheshire cat paradox is that its unique declare, that the particle and its property, equivalent to spin or polarization, separate and journey alongside completely different paths, could also be a deceptive illustration of the particular physics of the scenario.
“We want to correct this by showing that different results are obtained if a quantum system is measured in different ways, and that the original interpretation of the quantum Cheshire cat only comes about if you combine the results of these different measurements in a very specific way, and ignore this measurement-related change,” mentioned Holger Hofmann, a professor at Hiroshima University.
The crew analyzed the Cheshire cat protocol by analyzing the relation between three completely different measurements concerning the trail and polarization of a photon inside the quantum Cheshire cat protocol. These would have appeared to lead to a logical contradiction, had been the system not contextual. Their paper discusses how this contextual conduct hyperlinks to weak values, and the coherences between prohibited states. Through their work, they confirmed that as a substitute of a property of the particle being disembodied, the quantum Cheshire cat as a substitute demonstrates the consequences of those coherences, sometimes present in pre- and post-selected programs.
Looking forward the crew desires to broaden this analysis, to discover a solution to unify paradoxical quantum results as manifestations of contextuality, and to clarify as soon as and for all how and why measurements change quantum programs. “This will not only help us finally explain why quantum mechanics is so counterintuitive, but will also help us develop ways to use this weirdness for practical purposes. Given contextuality is inherently linked to scenarios where there is a quantum advantage over classical solutions to a given problem, only by understanding contextuality will we be able to realize the full potential of, for instance, quantum computing,” mentioned Hance.
The analysis crew contains Jonte R. Hance, Ming Ji, and Holger F. Hofmann from the Graduate School of Advanced Science and Engineering, Hiroshima University. Hance can also be a analysis affiliate within the Department of Electrical and Electronic Engineering on the University of Bristol.
The analysis was funded by Hiroshima University’s Phoenix Postdoctoral Fellowship for Research, the University of York’s EPSRC DTP grant, the Quantum Communications Hub that’s funded by EPSRC grants, and a JST SPRING grant.
