Why in News:
- The Nobel Prize in physics for 2022 is being awarded to Alain Aspect, John F. Clauser and Anton Zeilinger for their work on quantum mechanics.
- The 2022 Nobel Prize in Physics has been awarded “for experiments with entangled photons, establishing the violation of Bell inequalities, and pioneering quantum information science
- Classical mechanics is the study of the dynamics of a system which uses Newton’s laws of motion at the very basic level. However, this approach breaks down when one wishes to describe subatomic particles such as light quanta.
- Quantum mechanics is a subfield of physics that describes the behavior of particles — atoms, electrons, photons and almost everything in the molecular and submolecular realm.
- Electronic devices that we employ today use transistors that apply quantum mechanical ideas. Lasers have been built that apply the quantum properties of light. Other examples of technologies powered by quantum mechanics include MRI scanners for medical imaging, Lasers, Solar cells, Electron microscopes, Atomic clocks used for GPS, quantum computers, quantum cryptography
- Quantum entanglement is a bizarre, counterintuitive phenomenon that explains how two subatomic particles can be intimately linked to each other even if separated by billions of light-years of space.
- Despite their vast separation, a change induced in one will affect the other. In simple words, by measuring the properties of one particle, you automatically know the properties of the other particle. This is true however far apart the two particles are, provided the entanglement is not broken.
- This is what Einstein called ‘spooky action at a distance’ and prompted him, along with Boris Podolsky and Nathan Rosen to come up with the thought experiment (1935)— the case of Schrodinger’s cat which can be alive and dead at the same instant.
- The idea that challenged the very foundations of quantum mechanics was that there could be ‘hidden variables’ that decide the state of the particles that were separated in space, and there was no real quirk in quantum mechanics that caused them to be entangled.
- In the 1960s, John Stewart Bell developed the mathematical inequality that is named after him. 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.
- However, quantum mechanics predicts that a certain type of experiment will violate Bell’s inequality, thus resulting in a stronger correlation than would otherwise be possible.
What the three Nobel Prize winners’ work is based on?
- John Clauser built an apparatus that emitted two entangled photons at a time, each towards a filter that tested their polarisation. The result was a clear violation of a Bell inequality and agreed with the predictions of quantum mechanics. This means that quantum mechanics cannot be replaced by a theory that uses hidden variables.
- Alain Aspect– developed a setup to close an important loophole. He was able to switch the measurement settings after an entangled pair had left its source, so the setting that existed when they were emitted could not affect the result.
- Anton Zeilinger researched entangled quantum states. His research group has demonstrated a phenomenon called quantum teleportation, which makes it possible to move a quantum state from one particle to one at a distance.
- Here, physical particles are not teleported; however, information about their quantum states is moved through a distance — helping in new forms of communication and cryptography.
Significance of the discovery
- The 2022 Nobel Prize laureates in physics have conducted groundbreaking experiments using entangled quantum states, where two particles behave like a single unit even when they are separated. The results have cleared the way for new technology based upon quantum information.
- It has laid the foundation for a new era of quantum technology. Being able to manipulate and manage quantum states and all their layers of properties gives us access to tools with unexpected potential.
- Quantum teleportation uses the features of entanglement which can be used to transport information, carried by the object, to another place where the object is then reconstituted. This can be done without knowing the information, because to know the information would violate Heisenberg’s uncertainty principle which states that the position and the momentum of an object cannot both be measured exactly, at the same time, even in theory.
- Intense research and development are underway to utilise the special properties of individual particle systems to construct quantum computers, improve measurements, build quantum networks and establish secure quantum encrypted communication.
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