It takes three to tangle: long-range quantum entanglement needs three-way interaction
Infographic explaining the experiment. Credit: RIKEN

A study shows that long-range entanglement can survive at temperatures above absolute zero.

The next revolutionary step in computing is quantum computing. Current systems are stable at temperatures that are close to zero. A new theorem from a Japanese research collaboration provides an understanding of what types of long-range quantum entanglement survive at non-zero temperatures, revealing a fundamental aspect of macroscopic quantum phenomena and guiding the way towards further understanding of quantum systems.

When things get small, the laws of classical physics are replaced by those of quantum physics. The quantum world is strange and wonderful, but scientists don't know much about it. Large-scale quantum effects play a key role in extraordinary phenomena such as superconductivity, which is a potential game-changer in future energy transport, as well as for the continued development of quantum computers.

It is possible to observe and measure quantumness at this scale with the help of long-range quantum entanglement. Albert Einstein once described quantum entanglement as "spooky action at a distance", when a group of particles cannot be described independently. If you can fully describe one particle, you will know everything about the particles it is entangled with.

A breakthrough in quantum computing technologies is possible because of long-range entanglement. There are certain conditions in which long-range quantum entanglement is stable, such as between three or more parties. Two-party entangled systems at non-zero temperatures. Researchers from the RIKEN Center for Advanced Intelligence Project, Tokyo, and Keio University, Yokohama, presented a theoretical study in Physical Review X about long-range entanglement at temperatures above absolute zero in bipartite systems.

The purpose of our study was to identify a limitation on the structure of long-range entanglement at arbitrary non-zero temperatures, according to Tomotaka Kuwahara, one of the authors of the study. Particles in a material vibrate and move around due to thermal energy, which acts against quantum entanglement. No long-range entanglement can persist between only two subsystems at non-zero temperatures.

The findings are in line with previous observations that long-range entanglement can only survive at a non-zero temperature if more than three subsystems are involved. The results show that this is a fundamental aspect of quantum phenomena at room temperatures, and that quantum devices need to be engineered to have multipartite entangled states.

Keio University's Professor Keijo Saito states that this result has opened the door to a deeper understanding of quantum entanglement over large distances. Future quantum devices that work at room temperatures will be made practical by this knowledge.

While quantum devices that work at stable room temperatures are still in their infancy, quantum entanglement looks set to be the future of this field.

More information: Tomotaka Kuwahara et al, Exponential Clustering of Bipartite Quantum Entanglement at Arbitrary Temperatures, Physical Review X (2022). DOI: 10.1103/PhysRevX.12.021022 Journal information: Physical Review X Citation: It takes three to tangle: Long-range quantum entanglement needs three-way interaction (2022, May 6) retrieved 6 May 2022 from This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.