Scientists have captured a photograph for the first time of a phenomenon which Albert Einstein once described as “spooky action at a distance”.
The image is of a strong form of quantum entanglement, where two particles interact with each other and share their physical states for an instant — no matter how great the distance which separates them.
This connection is known as Bell entanglement and underpins the field of quantum mechanics.
Paul-Antoine Moreau, of the University of Glasgow’s School of Physics and Astronomy, said: “The image we’ve managed to capture is an elegant demonstration of a fundamental property of nature, seen for the very first time in the form of an image. It’s an exciting result which could be used to advance the emerging field of quantum computing and lead to new types of imaging.”
Einstein thought quantum mechanics was “spooky” because of the instantaneousness of the apparent remote interaction between two entangled particles. This seemed incompatible with elements of his special theory of relativity.
Scientist John Bell later formalised this concept by describing a strong form of entanglement exhibiting this feature. Bell entanglement is today being harnessed in practical applications like quantum computing and cryptography. However, it has never before been captured in a single image.
The team of physicists from the University of Glasgow described how they recorded the phenomenon in a photo for the first time.
They devised a system which fires a stream of entangled photons from a quantum source of light at “non-conventional” objects — displayed on liquid-crystal materials which change the phase of the photons as they pass through.