kvanttijaksoisuuden

Kvanttijaksoisuuden, known in English as quantum periodicity, is a phenomenon observed in certain quantum mechanical systems where a property exhibits periodic behavior as a function of some parameter. This parameter is often related to an applied magnetic field, a change in potential, or another external influence. The periodicity arises from the wave-like nature of quantum particles and the discrete energy levels that quantum systems can possess.

A prominent example of quantum periodicity is the Shubnikov–de Haas effect, observed in conductors at low temperatures and high magnetic fields. In this effect, the magnetoresistance of a material oscillates periodically with the inverse of the magnetic field. These oscillations are a direct consequence of the quantization of electron orbits in a magnetic field into Landau levels. As the magnetic field changes, Landau levels cross the Fermi energy, leading to changes in the density of states available for conduction and thus causing the resistance to oscillate.

Another related phenomenon is the de Haas–van Alphen effect, which manifests as oscillations in the magnetic susceptibility of a metal in response to a varying magnetic field. Similar to the Shubnikov–de Haas effect, these oscillations are also attributed to the quantization of electron orbits and the periodic passage of Landau levels through the Fermi surface. The periodicity of these quantum effects provides a powerful tool for investigating the electronic band structure and Fermi surface properties of materials. The understanding of quantum periodicity has been crucial in advancing condensed matter physics and materials science, enabling detailed characterization of quantum materials.