University Of Cambridge Physicists Discover Method To Track Quantum Particles When They’re Not Observed

Physicists may soon be able to decode the secret journeys of quantum particles with this new research.

University of Cambridge physicists believe they've developed a way to track quantum particles that are not observed.
Dean Mouhtaropoulos / Getty Images

Physicists may soon be able to decode the secret journeys of quantum particles with this new research.

The furtive world of quantum mechanics is one that has puzzled scientists ever since Erwin posited his Schrodinger’s cat paradoxical theory, in which his cat is in a quantum superposition state and is both alive and dead at the same time. Now, University of Cambridge physicists believe that they’ve figured out a way to finally track quantum particles when they’re not being observed.

Perhaps one of the most perplexing puzzles when it comes to quantum physics is that quantum objects are able to act as particles or waves, yet these particles and waves don’t truly exist until physicists decide to measure them. This has made it impossible so far for researchers to really figure out what they’re doing when they’re not being watched.

Cambridge University’s David Arvidsson-Shukur has explained that this wave function aspect of quantum mechanics has been used only as a tool so far, rather than as an actual method in which to investigate what quantum objects get up to when they’re not observed, something which led him and his team on their journey, as report.

“This premise, commonly referred to as the wave function, has been used more as a mathematical tool than a representation of actual quantum particles. That’s why we took on the challenge of creating a way to track the secret movements of quantum particles.”

Richard Feynman, one of the fathers of quantum mechanics, dancing with his wife in Sweden in 1965.
Richard Feynman, one of the fathers of quantum mechanics, dancing with his wife in Sweden in 1965. Keystone / Getty Images

Quantum particles are known to actively engage with their environment, a process that physicists term “tagging,” and it is this tagging that David Arvidsson-Shukur aims to attempt to map. Ph.D. student Axel Gottfries and Cavendish Laboratory’s Crispin Barnes have been working closely with Arvidsson-Shukur to devise a method to track these mysterious quantum particles on their journeys, and their results have been published in the scientific journal Physical Review A.

Physicists working in the field of quantum physics have postulated that two people are able to transmit information between each other, but without having any particles moving between the two of them, a form of communication which could be called telepathic, and which has been given the name of counterfactual communication. This name is derived from the fact that it surely must go against everything we know today to have communication between two sources without any particles involved between them.

However, in order to properly measure this type of communication, a way must be found to determine just where, exactly, these quantum particles are at when they’re not being observed and when this communication is actually happening, according to David Arvidsson-Shukur.

“To measure this phenomenon of counterfactual communication, we need a way to pin down where the particles between Alice and Bob are when we’re not looking. Our ‘tagging’ method can do just that. Additionally, we can verify old predictions of quantum mechanics, for example that particles can exist in different locations at the same time.”

There have been many different possibilities proposed of what quantum particles may be doing when then they’re not being observed, including, of course, the idea that these particles are in two places at once. In their new study, these University of Cambridge physicists describe how particles whizzing through space will always be interacting with whatever environment they find themselves in.

It is precisely this tagging that will allow physicists to find information that has been encoded in the quantum particles once their experiments have been concluded and they are able to scientifically measure these particles.

And, excitingly, the wave function that Schrodinger once described has been found to be related to the secret information hidden inside of quantum particles describing their journeys.

“Our result suggests that the wave function is closely related to the actual state of particles. So, we have been able to explore the ‘forbidden domain’ of quantum mechanics: pinning down the path of quantum particles when no one is observing them.”

Now that physicists have found a way to determine just what quantum particles are doing when they’re not being observed, we can look forward to many new studies describing the mysterious paths that these particles take.