SPOOKY QUANTUM ENTANGLEMENT

 

The 2022 Nobel Prize in physics has been awarded to three researchers for their pioneering experiments in quantum information science, a burgeoning field that could revolutionize computing, cryptography and the transfer of information via what is known as “quantum teleportation.”

The three physicists are John F. Clauser, 79, of Walnut Creek, Calif., Alain Aspect, 75, of the Université Paris-Saclay and École Polytechnique in France, and Anton Zeilinger, 77, of the University of Vienna.

Quantum mechanics is nowadays a vast field of application based research in various areas including quantum computers, quantum networks and secure quantum encrypted communication. 

Quantum mechanics allows two or more particles to exist in what is called an 'entangled state'. The effect on one of the particles in an entangled pair determines the effect on the other particle  in the same entangled pair, even when they are far apart from each other. 

Quantum mechanics describes the behaviour of sub-atomic particles. It's a field that was opened up in the early 20th Century. It concerns something called "entanglement" in which two or more quantum particles - usually photons, the particles of light - can be strongly connected when very far apart even though they are not physically linked.

Their shared state might be their shared  energy or their shared  spin. Albert Einstein colorfully dismissed quantum entanglement i.e., the ability of separated objects to share a condition or state, as “spooky action at a distance.” The theoretical foundation of "Quantum Entanglement' was developed in the 1960s by Northern Irish physicist John Stewart Bell. 

 John Bell proposed a mathematical test known as Bell’s inequality. This states that if there are hidden variables, the correlation between the results of a large number of measurements will never exceed a certain value. 

This said that experimental results that seemed to be correlated beyond a particular value would be possible only through quantum entanglement, rather than being due to certain kinds of hidden variable. Quantum mechanics predicts a higher degree of correlation than would be possible in classical, or pre-quantum, physics.

Bell’s technique relied on detecting one pair of particles at a time, but this approach is not useful for studying solid materials composed of trillions and trillions of particles. 

1972,  a physicist  J.F. Clauser & Associates in Walnut Creek, California  developed these ideas into a practical experiment that violated the Bell inequality, supporting the theories of quantum mechanics. 

But Clauser’s  experiments had some  loopholes , that left room for hidden variables to create the illusion of quantum entanglement. His experiments used a changing set-up which meant that experimental decisions could not be said to be predetermining the results.

In 1997, Zeilinger & his colleagues at the University of Vienna used the phenomenon of entanglement to demonstrate quantum teleportation, in which a quantum state gets transmitted from one location to another.

Quantum systems cannot be detected and reconstituted at other location, because measurement destroys their delicate quantum properties. But a state can be transferred between two particles at a distance, if each is entangled with half of a previously entangled pair.  

Teleportation allows for super-secure communications, because any eavesdropping would cause particles to lose their delicate quantum states. It might also enable future quantum computers to transfer information. Since Zeilinger’s initial experiments, physicists have succeeded in teleporting electrons, as well as atoms and superconducting circuits.

This invention of “Quantum Entanglement” will pave the way to a new generation of powerful computers and telecommunications systems . 

Quantum information science is a vibrant and rapidly developing field. It has broad and potential implications in areas such as secure information transfer, quantum computing, and sensing technology. 

In recent experiments, Zeilinger, along with Kaiser and others, has worked on the loopholes in tests of Bell’s inequality by using properties of starlight, emitted billions of years ago in order to, define experimental settings.

Two areas of entanglement research are very popular today. One is in quantum computers which promises an upgradation in the ability to solve complex problems. While the other is in encryption, the secure encoding of information. Exploiting entanglement will make it impossible for a third party to eavesdrop on private communications. 

According to John Clauser, it is useful for military and banking, etc, in secure communications. The biggest application of Quantum Entanglement is the Chinese satellite launched several years ago , which  they used for secure communications over thousands of kilometres. 

Due to Quantum Entanglement measuring the property of one particle in an entangled pair immediately affects the results of measurements on the other.  This enables quantum computers to function.

 It seek to harness quantum particles’ ability to exist in more than one state at once, carry out calculations that would be impossible on a conventional computer. Today, physicists are using entanglement to develop quantum encryption and a quantum internet that would allow for ultra-secure communications and new kinds of sensors and telescopes.

According to research workers, one hope, is that they will show whether two particles can become entangled through a gravitational interaction. 

General relativity is apparently incompatible with quantum mechanics & such experiments could provide hints on how to develop a quantum theory of gravity to replace it.