Quantum mechanical tunneling

Definition

Quantum mechanical tunneling is a quantum phenomenon where a particle passes through a potential barrier that it classically shouldn't be able to surmount. This occurs due to the wave-like properties of particles in quantum mechanics.

5 Must Know Facts For Your Next Test

1. In quantum mechanics, particles such as electrons can 'tunnel' through energy barriers even if they do not have sufficient energy to overcome the barrier classically.
2. Tunneling is crucial for understanding nuclear fusion in stars, where particles tunnel through the Coulomb barrier.
3. The probability of tunneling decreases exponentially with increasing barrier width and height.
4. Quantum tunneling is responsible for radioactive decay processes such as alpha decay, where an alpha particle tunnels out of the nucleus.
5. Tunneling has practical applications in modern technology, including tunnel diodes and scanning tunneling microscopes (STM).

Review Questions

• What allows particles to tunnel through potential barriers in quantum mechanics?
• How does the probability of tunneling change with respect to the width and height of the potential barrier?
• Name one real-world application or natural process that relies on quantum mechanical tunneling.

Related terms

Alpha Decay: A type of radioactive decay where an unstable nucleus emits an alpha particle (two protons and two neutrons) by tunneling out of the nucleus.

Wave-Particle Duality: A fundamental concept of quantum mechanics stating that every particle exhibits both wave and particle properties.

Potential Barrier: An energy barrier that a classical particle cannot cross without sufficient energy but which can be tunneled through in quantum mechanics.