13 Oct 2022 Nobel in Physics for quantum entanglement
Source: The Hindu; The Indian Express
News: Physicists Alain Aspect from France; John F. Clauser from the U.S. and Anton Zeilinger from Austria were selected for the 2022 Physics Nobel.
Image Credit: The Hindu
Contribution of these three physicists:
- This year’s Nobel prize has been given for experimental work in quantum entanglement or in words of Einstein ‘spooky action at a distance’.
- According to the Academy of Sciences these scientists have been awarded “for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science”.
- These scientists established the fact that ‘entanglement’ in quantum particles are not due to any ‘hidden’ or unknown forces, but is real.
- John Clauser and Alain Aspect firmed up the concept of ‘ spooky action at a distance’ or quantum entanglement through demonstration of more and more complex experiments. John Clauser and Alain Aspect by creating, processing and measuring Bell pairs established the fact that entanglement was indeed a true characteristic of quantum mechanics.
- Anton Zeilinger innovatively used entanglement and Bell pairs in quantum computation and quantum cryptography research and applications. He and his group performed quantum teleportation (In this information is conveyed from one place to another without actual transport of material)through the phenomenon of entanglement.
Quantum revolution:
- Classical mechanics is based on Newton’s laws of motion. It helps to study the dynamics of a few bodies or particles interacting with each other and a system. However, classical mechanics fails to describe subatomic particles such as light quanta.
- Concepts of classical mechanics failed to visualize the movement of particles obeying quantum mechanics.
- Postulates of quantum mechanics were invoked by Max Planck, Albert Einstein, Erwin Schrodinger, Werner Heisenberg and Niels Bohr to explain problems associated with subatomic particles.
- One of the key difference between behaviour of quantum systems and classical bodies is the concept of entanglement.
Origin of the theory:
- Quantum theory: Quantum Theory allowed a particle to exist simultaneously at multiple locations, a phenomenon known as superposition. Once a particle was found, or observed, at one location, it ceased to exist at all other places.
- Einstein termed quantum entanglement as ‘spooky action at a distance’. Einstein along with Boris Podolsky and Nathan Rosen came up with Schrodinger’s cat thought experiment in 1935 where Schrodinger’s cat can be alive and dead at the same instant. This experiment challenged the foundations of quantum mechanics with the notion that there might be “hidden variables” that determine the state of the particles that are separated in space and that there is no actual quirk in quantum physics that causes them to be entangled.
- John Bell showed mathematically through Bell’s inequality what was required to be done to establish the phenomenon of entanglement. If Bell’s inequality is maintained in the experiment, it would mean that Einstein was right and if Bell’s inequality is violated, it would prove the predictions of Quantum Theory.
- Clauser’s entanglement experiments in 1972 clearly violated Bell’s inequality. Further, Aspect’s experiments also violated Bell’s inequality and removed all the loopholes of Clauser’s experiment.
- Anton Zeilinger opened up new technological possibilities by exploiting entanglement property: He ‘teleports’ the quantum states of a particle to another location without a medium or without moving the particle anywhere.
- Experiments of Clauser, Aspect and Zeilinger demonstrated that entanglement was real and in line with Quantum Theory . There are no hidden forces that drive the entanglement as suggested by Einstein.
Concept of quantum entanglement:
- Quantum entanglement allows a pair of particles, like photons, to exist in a shared state where their properties are complementary.
- Due to a quirk of quantum mechanics, two or more particles exist in an ‘entangled state’ irrespective of distance, meaning what happens to one particle affects the others immediately or behaviour in one particle instantaneously produces reaction in another.
- Due to the complementary nature of a particle’s properties, the properties of one particle tell the qualities of the other particle irrespective of distance as long as the entanglement is maintained.
Use of quantum mechanics:
- Quantum mechanical ideas have application in electronic devices such as transistors.
- Quantum properties of light are used to build the Lasers.
- Quantum technologies of the future such as quantum cryptography, and precise timekeeping in atomic clocks can be developed with the work of the three laureates.
- Quantum entanglement can be utilized in computing to make hack-free communications through secure communications algorithms.
- It can help to actualize science fiction-like concepts of ‘teleportation’ through advancement in transformative technologies.
- Researchers have demonstrated the entangled quantum states between photons on earth and those on a satellite: Through optical fibres photons traversed tens of kilometres of optical fibres.
- Quantum entanglement allows for transmission of information at speeds faster than light.
- Next generation of computers or quantum computers can be built by exploiting entanglement properties of quantum particles to overcome insurmountable challenges.
- Quantum entanglement will help to make significant progress in the fields of quantum key distribution
Articles:
1.No longer bizarre: On 2022 Physics Nobel
2.Explained | What lies at the heart of the 2022 Physics Nobel?
3.No longer bizarre: On 2022 Physics Nobel.
Article Link:
1.https://www.thehindu.com/opinion/editorial/no-longer-bizarre-the-hindu-editorial-on-the-2022-nobel-prize-for-physics/article65976282.ece
2.https://www.thehindu.com/sci-tech/science/explained-what-lies-at-the-heart-of-the-2022-physics-nobel/article65985835.ece
3.https://indianexpress.com/article/explained/explained-sci-tech/breakthroughs-in-quantum-tech-nobel-prize-2022-8190213/
Yojna daily current affairs eng med 13 Oct 2022
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