Quantum Tunneling: Wavepackets and Probability Amplitudes

What Quantum Tunneling Is

Quantum tunneling is a phenomenon where particles can pass through potential barriers that are higher than their energy, which is impossible according to classical physics. This effect arises from the wave nature of particles and is described by quantum mechanics.

The concept of tunneling has numerous applications in modern technology, including scanning tunneling microscopy (STM) and semiconductor devices like transistors.

How Wavepackets Exhibit Tunneling

Wavepackets are localized waveforms that represent particles. In the context of quantum mechanics, a particle's state is described by a wavefunction, which gives the probability amplitude for finding the particle at any given position.

When a wavepacket encounters a potential barrier, it can partially pass through (tunnel) and emerge on the other side due to interference effects between different parts of the wavepacket.

Why It Matters

Quantum tunneling is crucial in understanding the behavior of particles at atomic scales, which has led to significant advancements in technology. For instance, STM allows scientists to image individual atoms and molecules.

In semiconductor devices, tunneling plays a vital role in the operation of certain components like quantum dots and tunnel diodes.

Real-World Examples

One practical application is in scanning tunneling microscopy (STM), where an atomic-scale tip is brought close to a surface, and electrons can tunnel from the tip to the surface or vice versa, allowing for imaging at the atomic level.

Another example is in quantum computing, where tunneling effects are used to control qubits, enabling quantum bits to exist in multiple states simultaneously.

Frequently asked questions

Try it live

Everything above runs in your browser — open Quantum Tunneling Wavepacket Lab and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.