In the 1930s, the venerable theoretical physicist Albert Einstein returned to the field of quantum mechanics, to whose emergence his relativity theories contributed. Hoping to develop a more complete theory of the behavior of particles, Einstein was instead horrified by the prospect of a quantum entanglement, which he called "spooky action at a distance."
Despite Einstein's concerns, quantum entanglement has become an accepted part of quantum mechanics. And now, for the first time, a team of physicists at the University of Glasgow has captured a picture of quantum entanglement (aka Bell entanglement) at work. In this way, they managed to provide the first visual proof of a phenomenon that even astonished even Einstein himself.
The paper, entitled "Imaging Bell-type Nonlocal Behavior," which described its findings, appeared recently in the journal Advances in Science . The study was Paul-Antoine Moreau, a Leverhulme Early Career Fellow at the University of Glasgow, directed and included several researchers from the Glasgow School of Physics & Astronomy. Picture credits: Discovery News.
Quantum entanglement describes the phenomenon in which two particles that interact with each other can remain connected and share their physical states instantaneously, regardless of how far apart they are from each other. This connection is at the heart of quantum mechanics, though it violates the concept of local realism and many elements of Special Relativity.
Until 1964, Sir John Bell extended the work of earlier theorists by formalizing the concept of non-local interaction and describing a strong form of entanglement. This would be known as Bell entanglement, a concept used for various scientific applications – such as quantum computers and cryptography.
And yet it has never been captured in a single picture. Dr. Moreau said in a Glasgow University press release:
"The image we took is an elegant demonstration of a fundamental property of nature that was first seen in the form of an image. It is an exciting result that could be used to advance the emerging field of the quantum computer and lead to new types of imaging. "
For their study's sake, the research team developed a system in which a stream of photos gets entangled by a quantum light source. This current then passes through a series of "non-conventional objects", which are liquid crystal materials that change the phase of the photons as they pass through.
The setup also included a high-sensitivity camera that captures and captures individual photons. However, the camera has been programmed to only take pictures when both a photon and its twins are visible. In this way, the experiment succeeded in visualizing the entanglement of two photons.
The results of this study open up a whole new world of quantum techniques using Bell entanglements. It also has implications for quantum information (ie quantum computers and cryptology)
Further reading: University of Glasgow, Science Advances