for the first time It was possible to reconstruct the wave nature of the electron in the laboratory, the Bloch wave function. This was done by scientists from the University of California, Santa Barbara (UCSB), and their work may find application in designing future generations of electronic and optoelectronic devices.
Electrons behave like a particle and a wave. Scientists describe their wave nature using mathematical objects called wave functions. These jobs have both real and fictional components. For this reason, the Bloch wave function of the electron cannot be measured directly. However, you can observe the relevant properties. Physicists have long tried to understand how the wave-like nature of electrons moving through the crystal lattice of atoms gives electronic and optical properties to this lattice. Understanding this phenomenon will allow us to design devices that make better use of the wave nature of the electron.
Santa Barbara scientists used a powerful free-electron laser to generate an oscillating electric field in semiconducting gallium arsenide. At the same time, using a low-frequency infrared laser, they excited its electrons. The excited electrons leave positively charged “holes”. As Mark Sherwin explains, in gallium arsenide, these holes come in two types — light and heavy — and behave like particles of different masses.
Physicists at UCLA found that if they form electrons and holes in time with an electric field oscillation, the components of the pairs of quasiparticles formed, called excitons, first diverge, then slow down, stop, and begin accelerating toward each other, coming To them, collision and recombination. When recombined, they emit a pulse of light – called a sideband – with a characteristic energy. This emission contains information about the wave function of the electrons, including their phases.
Because the light and heavy holes accelerate at different rates in the electric field, the Bloch wave functions have different phases before recombining with the electrons. Because of this phase difference, the wave functions and their emissions overlap, which can be measured. This interference also determines the sideband polarization. It can be circular or oval.
The authors of the experiment emphasized that a simple measurable ratio between interference and polarization is a sufficient condition to link quantum mechanics theory to real phenomena. This single parameter perfectly describes the hole Bloch wavefunction obtained in gallium arsenide. We get this value by measuring the sideband polarization and then reconstructing the wavefunction, which may vary depending on the angle of hole propagation in the crystalSeamus O’Hara adds.
What could such research be useful for? Until now, scientists have had to rely on theories containing many poorly understood elements. Now that we can accurately reconstruct the Bloch wave function for different materials, we can use this to design and build lasers, sensors, and some components of quantum computers.The researchers explain.
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