Nearly a hundred years ago, Albert Einstein and Satyendra Nath Bose predicted that quantum mechanics can force a large number of particles to behave in concert as if they were only a single particle. The phenomenon is called Bose–Einstein condensation, and it took until 1995 to create the first such condensate of a gas of alkali atoms.
Although Bose–Einstein condensation has been observed in several systems, the limits of the phenomenon need to be pushed further: to faster timescales, higher temperatures, and smaller sizes. The easier creating these condensates gets, the more exciting routes open for new technological applications. New light sources, for example, could be extremely small in size and allow fast information processing.
In experiments by Aalto researchers, the condensed particles were mixtures of light and electrons in motion in gold nanorods arranged into a periodic array. Unlike most previous Bose–Einstein condensates created experimentally, the new condensate does not need to be cooled down to temperatures near absolute zero. Because the particles are mostly light, the condensation could be induced in room temperature.
‘The gold nanoparticle array is easy to create with modern nanofabrication methods. Near the nanorods, light can be focused into tiny volumes, even below the wavelength of light in vacuum. These features offer interesting prospects for fundamental studies and applications of the new condensate,’ explains Academy Professor Päivi Törmä.
The main hurdle in acquiring proof of the new kind of condensate is that it comes into being extremely quickly.