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Picture Courtesy: Times of India

Context:

The 2025 Nobel Prize in Physics was awarded for experiments demonstrating that quantum tunnelling, a hallmark of the microscopic world, can also manifest in an electrical circuit large enough to be observed directly.

What is Quantum Tunnelling?

Quantum tunnelling is a phenomenon in quantum mechanics where particles pass through a potential energy barrier that, according to classical physics, they should not be able to cross. Unlike classical objects, quantum particles behave as waves, and these wavefunctions can extend through—and even emerge from—the other side of a barrier.

How does it work?

The process relies on the nature of quantum wavefunctions. Even when a particle does not have enough energy to overcome the barrier classically, its wavefunction can "leak" through the barrier. If the barrier is thin enough (typically between 1–3 nanometres), there is a non-zero probability that the particle will be found on the other side.

Applications of Quantum Tunnelling:

Superconducting Qubits: Superconducting circuits that mimic the behaviour of artificial atoms. These circuits form the basis of qubits—the fundamental units of quantum information in many of today’s most advanced quantum computers.

Quantum Sensors: These devices can detect extremely subtle changes in magnetic fields, temperature, or gravitational variations. Helps in Medical diagnostics, Geophysical exploration.
Quantum Amplifiers: Amplify very weak signals with minimal added noise—a critical requirement in quantum experiments. For e.g. Space missions, Dark matter research.

Quantum Metrology: Josephson junctions now form the basis for defining units like the volt and ampere. These quantum-based standards ensure uniformity in electrical measurements across the world, with accuracy grounded in fundamental physics rather than mechanical instruments.

Quantum Communication: To create secure, global-scale quantum communication networks.

Source: Times of India

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Practice Question

Q. Describe the significance of the experiments conducted by Clarke, Devoret, and Martinis that led to their Nobel Prize in Physics in 2025.

Frequently Asked Questions (FAQs)

Quantum tunnelling is a quantum mechanical phenomenon where particles pass through an energy barrier that they classically shouldn’t be able to cross. This happens because the particle’s wavefunction extends beyond the barrier, allowing a finite probability of appearing on the other side.

In classical physics, particles need enough energy to overcome a barrier. Quantum tunnelling allows particles to "tunnel" through barriers without having to climb over them, which is impossible according to classical mechanics.