Plasmons Shown to have Important Quantum Property
Some day we want to see quantum computers running advanced algorithms no modern computer is capable of. Before that can happen though, we have to develop the technologies and understanding necessary to build quantum computers. Researchers at the California Institute of Technology have made an important discovery concerning both the required technologies and understanding.
Photons and electrons are two interesting particles with very different properties that make them ideal for certain, distinct applications. There is one quasi-particle that exists between these two, called a plasmon. Plasmons are oscillations of the surface electrons of a metal that reach the frequencies of light, and can be produced when a photon strikes a metal's surface. Because plasmons exist between electrons and photons, researchers have not been certain if its behavior can be described with quantum mechanics. To test this, the Caltech researchers found a way to replicate an optical experiment concerning quantum interference with plasmons. Normally one would fire two identical photons into a beam splitter, and quantum interference will cause the photons to exit on the same side. In this experiment two plasmons made by two identical photons pass through two waveguides to a directional coupler, which acts like a beam splitter.
The researchers found that, like with the photons and beam splitter, the two identical plasmons exited from the same side of the directional coupler. This demonstration of quantum behavior with plasmons could potentially lead to chip-based quantum devices and circuits, utilizing plasmons.