Summary
Highlights
Quantum tunneling is introduced, where an electron's wave function can extend beyond a potential barrier, even without sufficient energy to cross it classically. This means there's a small probability of finding the electron outside its binding force. Scientists can manipulate this by applying an electric field, distorting the atom's potential energy landscape and making the barrier thinner, allowing the electron's cloud to leak out.
The video starts by explaining that an electron exists as a probability cloud, not a simple particle. This cloud can take different shapes, each described by a wave function, depending on the electron's energy state. Before measurement, an electron is a hazy puff of smoke representing possibilities, and upon observation, it collapses into a single particle.
Electrons behave like probability waves. Atomic energy levels are not physical shells but different distributions of the electron's probability wave (wave function) around the nucleus. For instance, in a hydrogen atom's ground state, the electron's wave is a spherical cloud. Absorbing energy changes the wave's shape and size, and invisible nodes exist where the electron's probability is zero.
The 2025 Nobel Prize in Physics was awarded to John Clark, Michael H. Devore, and John M. Martinez for demonstrating that quantum effects apply to larger engineered systems. They used Josephson junctions—thin insulating layers between superconductors—where Cooper pairs behave as a single quantum wave that can tunnel through the barrier. This phenomenon is analogous to atomic tunneling.
In a Josephson junction, the superconducting wave exists in a potential well, taking on different shapes and energy levels. Scientists control these states using microwave pulses. The lowest energy state represents '0', and the next represents '1', allowing the wave to exist in a superposition of both states. By manipulating and reading the tunneling behavior, these junctions function as qubits in quantum computers.
The Nobel laureates' work proved that circuits made of millions of electrons can exhibit quantum tunneling, a phenomenon previously thought to be exclusive to the microscopic world. Their experiments showed these circuits absorb and emit energy in discrete amounts, similar to atoms. This led to the creation of 'artificial atoms' that are foundational for quantum computers, advanced sensors, and other future quantum technologies.