Nobel Prize in Physics: Breakthroughs in quantum tech
- October 5, 2022
- Posted by: OptimizeIAS Team
- Category: DPN Topics
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Nobel Prize in Physics: Breakthroughs in quantum tech
Subject: Science and Technology
Context:
- The Nobel Prize committee decided to honour three scientists — Alain Aspect of France, John Clauser of the US, and Anton Zeilinger of Austria.
- Their experiments have conclusively established that the ‘entanglement’ phenomenon observed in quantum particles was real, not a result of any ‘hidden’ or unknown forces and that it could be utilised to make transformative technological advances in computing, hack-free communications, and science fiction-like concept of ‘teleportation’.
Background of Quantum theory–
- By the start of the 20th century, a few scientists observed that the behaviour of tiny sub-atomic particles like protons or electrons was not consistent with the classical Newtonian laws of physics.
- Over the next 30 years, they together strung the Quantum Theory, which described the seemingly bizarre behaviour of sub-atomic particles with remarkable accuracy.
- But Quantum Theory went completely against everyday experiences.
- It allowed a particle to exist simultaneously at multiple locations, a phenomenon known as superposition.
- The chance of finding the particle at any given place was dictated by probabilistic calculations, and once it was found, or observed, at one location, it ceased to exist at all other places.
- Entanglement was another of several weird properties exhibited by these tiny particles.
- Two particles, having ‘interacted’ with each other at some stage, were found to have got ‘entangled’ in a way that the behaviour of one produced an instantaneous reaction in the other even if the two were no longer connected in any way and were separated by very large distances.
Einstein’s objection–
- Einstein, in particular, was extremely uncomfortable with this.
- His Special Theory of Relativity prohibited any signal from travelling faster than the speed of light.
- The seemingly instantaneous communication due to entanglement had the danger of further unravelling the foundations of physics.
- Einstein proposed that there was something missing, and that Quantum Theory was not yet complete.
Bell’s inequality–
- Experimentalists, in the meanwhile, were discovering that almost every prediction made by Quantum Theory was being obeyed by the sub-atomic particles.
- The theory was remarkably accurate.
- The problem was that an experiment to test a phenomenon like entanglement did not appear feasible.
- John Bell in 1964, showed mathematically what was required to be done by experimentalists to establish the phenomenon of entanglement.
- The famous Bell’s inequality, if maintained in the results of the experiment, would mean that Einstein was right.
- If violated, it would prove the predictions of Quantum Theory.
Experiments of Clauser, Alain and Zeilinger–
- The 79-year-old Clauser was the first to set up an experiment to test entanglement.
- In 1972, his experiments produced results that were a clear violation of Bell’s inequality.
- But sceptics pointed to certain aspects of the experiment which could have influenced a favourable result.
- Alain Aspect is credited with vastly improving the set-up of Clauser and removing all the loopholes critics had found. Aspect’s experiments also produced results that violated Bell’s inequality.
- Anton Zeilinger, and his colleagues, in the meanwhile, had already started exploiting the entanglement property to open up new technological possibilities.
- Zeilinger demonstrated for the first time that it was possible to ‘teleport’ the quantum states of a particle to another location without the particle moving anywhere and without a medium.
- These experiments conducted by Clauser, Aspect and Zeilinger have decisively demonstrated that entanglement was real and in accordance with the Quantum Theory, and that it was not being driven by any hidden forces as suggested by Einstein and others.
Application of quantum theory–
- The entanglement property is now being utilised to build the next generation of computers, called quantum computers.
- It is being used to create secure communication algorithms that would be immune to hacking.