The Nobel Prize in Physics 2025 was awarded to  John Clarke, Michel H Devoret, and John M. Martinis for the discovery of macroscopic quantum mechanical tunnelling and energy quantisation in an electric circuit.

Domains of Physical Reality

Physics is divided into two domains

• Classical Physics: Governs the macroscopic world, where Newton’s laws predict motion with certainty.
• Quantum Physics: Quantum effects are generally observable in one or very few small particles such as atoms or photons. These particles do not follow the classical laws of physics.

Key Quantum Phenomena

• Tunnelling: A particle can cross a physical barrier.
• Superposition: A particle can exist in multiple locations at once.
• Entanglement: Two particles that have interacted can influence each other even when far apart.
• Energy Quantisation: Energy exists in discrete packets or “quanta,” meaning atoms jump between energy bands rather than changing energy continuously.

The Nobel-Winning Experiment and Discovery

• Setup: Starting in the 1980s, the scientists created an electrical circuit made of two superconductors separated by a thin non-conducting layer. 
  • Superconductors can carry current without electrical resistance, while the separating layer blocks direct current flow.
• Observation: Although classical physics dictates that current cannot pass through an insulator, the experiment showed tunnelling. Particles from one superconductor “teleported” across the insulator barrier to the other.
  • Macroscopic Tunneling: This was the first time macroscopic tunnelling was observed in a structure man-made by humans. 
  • Energy Quantisation: The circuit absorbed and emitted energy in discrete amounts rather than a continuous flow, confirming quantum behaviour at a macroscopic scale.

Broader Significance Of the Discovery

• Relevance to Quantum Computing: The discovery is crucial for developing quantum computers, which use quantum mechanical principles to perform complex computations.
• Applications:
  • Scientific Research: Enables modelling of molecules at a quantum level, aiding faster drug and material design.
  • Encryption: Quantum computers can break encryption faster, and thus also create more-difficult-to-break encryption.
  • Climate Modeling: Quantum computers could simulate the Earth’s entire climate system, providing accurate, early information about cyclones, floods, and droughts, which current supercomputers cannot do.
  • Finance: Portfolio Optimisation, Revolution in Risk and Fraud Detection.

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India’s Efforts

• Funding Allocation: The government allocated ₹6,000 crores in 2023 to promote quantum mechanics research, reflecting a strong commitment to advancing cutting-edge science.
• Research Focus and Hubs: The research primarily focuses on quantum computing, communication, and sensing, with key centres located at IISc Bengaluru, TIFR Mumbai, and IIT Mumbai to drive innovation and technological development.

Conclusion

The 2025 Nobel Prize in Physics highlights the first observation of macroscopic quantum tunnelling and energy quantisation, bridging fundamental theory and practical applications, paving the way for quantum computing, advanced research, and India’s scientific leadership.

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