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Introduction

The 2025 Nobel Prize in Physics showed that quantum effects can also appear in large, visible systems like superconducting circuits. Two key ideas behind this are quantum tunnelling, where particles cross barriers they normally shouldn’t, and energy quantisation, where energy exists in fixed packets instead of continuous values.

Concept of Quantum Tunnelling & Energy Quantisation

A. Quantum Tunnelling

• Definition:  Quantum tunnelling is a phenomenon where a particle passes through an energy barrier that it classically shouldn’t overcome. This happens because, in quantum theory, particles behave like waves that can “leak” through barriers.
  Eg: In alpha decay of uranium, helium nuclei tunnel through the nuclear potential barrier to escape.
• Wave-Particle Duality:  Every particle has a wavefunction that represents the probability of finding it somewhere. Even if energy is less than the barrier height, the wavefunction extends beyond the barrier, giving a finite chance of crossing.
• Probability and Barrier Thickness:  The thicker or higher the barrier, the lower the tunnelling probability but it never becomes zero.
  Eg: Scanning Tunnelling Microscope (STM) uses this effect to map surfaces atom by atom.
• Physical Meaning:  Tunnelling reflects the probabilistic nature of the universe reality is governed by chances, not certainties.
  Eg: Fusion reactions in the Sun occur only because protons tunnel through repulsive electrostatic barriers.

B. Energy Quantisation

• Definition:  Energy in quantum systems exists in fixed packets (quanta), not continuous values. Particles can occupy only specific allowed energy levels.
  Eg: Bohr’s model of hydrogen shows electrons jumping between fixed energy orbits.
• Reason for Quantisation:  Only certain standing wave patterns fit perfectly in atomic orbits, restricting allowed energy states.
• Experimental Evidence:  Discrete spectral lines in hydrogen or sodium vapour lamps confirm that atoms absorb or emit specific energy quanta (photons).
• Quantisation in Macroscopic Systems:  The Nobel laureates showed quantised current flow in superconducting loops  proving that even macroscopic systems follow quantum laws.

Implications

A. Theoretical Foundations of Quantum Physics 

• Extension of Quantum Laws: Confirms that quantum mechanics is universal, not limited to atoms quantum behaviour persists in larger systems.
• Bridging Quantum–Classical Divide: Provides experimental proof that quantum coherence can exist in visible-scale objects, redefining the boundary between classical and quantum worlds.
• Strengthening Quantum Field Theory: Observed tunnelling and quantised states match predictions of advanced theories like quantum electrodynamics (QED).
• Foundation for Quantum Technology: Establishes the physical basis for quantum computing, cryptography, and sensing systems.

B. Practical Applications

• Electronics: Tunnel diodes and Zener diodes use electron tunnelling for high-speed switching.
• Quantum Computing: Superconducting qubits exploit quantised energy levels and tunnelling to store and process quantum information.
• Energy and Fusion: Understanding tunnelling explains how nuclear fusion occurs in the Sun and aids artificial fusion research.
• Medical Imaging: Quantised energy transitions underpin MRI and PET technologies.
• Nanotechnology: STM and quantum dots use tunnelling to control and image matter at atomic scales.
  

Conclusion

Quantum tunnelling and energy quantisation show that nature works in tiny, precise steps rather than smoothly. The 2025 Nobel discovery proves that these quantum rules apply not just to atoms but even to bigger systems, helping build new technologies like quantum computers and advanced electronics.

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