World's fastest Bose-Einstein condensate

Date:
June 22, 2020
Source:
Aalto University
Summary:
Researchers have created a Bose-Einstein condensate with record
speed, creating the fascinating phase of matter in about 100
femtoseconds. To get an idea of how quick that is, hundred
femtoseconds compared to one second is proportionally the same as
a day compared to the age of the universe.



FULL STORY ========================================================================== Researchers have created a Bose-Einstein condensate with record speed,
creating the fascinating phase of matter in about 100 femtoseconds. To
get an idea of how quick that is, hundred femtoseconds compared to one
second is proportionally the same as a day compared to the age of the
universe. The project was the result of a collaboration between Aalto University the and University of Eastern Finland.


========================================================================== Bose-Einstein condensation is a quantum phenomenon where a large number
of particles starts to behave as if they were one. Albert Einstein and Satyendra Nath Bose predicted this fascinating behavior in the beginning
of last century.

Many different systems, like gases of alkali atoms or semiconductors
coupled with light, have been used for observing these condensates. None
of them comes into being, however, as fast as the Finnish researchers' Bose-Einstein condensate.

Bose-Einstein condensates composed of light are similar to lasers and particularly promising for information and quantum technologies. The information transfer of the internet today relies on the high speed
of light.

In principle, light can also be used to provide ultrafast computing with
low energy consumption, but achieving this requires pushing the limits
of what we know about the interaction of light with matter.

In our everyday world, water molecules of humid air condense on the
surface of a cold beer can. Similarly, in the quantum world, particles
have to find a way to lose their energy in order to condense to the
lowest possible energy state.

This process typically takes time from thousands of a second to
trillionths of a second. How was it possible to form a condensate even
faster? 'After carefully analyzing our measurement data, we realized that
the energy relaxation in our system is a highly stimulated process. This
means that the effective interaction of photons, which leads into
condensation, accelerates when the number of photons increases. Such
a phenomenon is the key for the speed-up,' explains Aaro Va"keva"inen
who completed his PhD degree with these results. Another challenge
was to prove that condensation indeed happens with record speed, since
even advanced lab cameras fall short of such time resolution. 'When we
pumped energy into the molecules in 50 femtoseconds, the condensate
was observed. But with 300 femtosecond pump pulse we did not see it,
which indicated that the condensation must be triggered even faster,'
says doctoral student Antti Moilanen.

'This condensate produces a coherent light beam that is 100,000 times
brighter than the first surface plasmon polariton condensate we observed
in a metal nanorod array two years ago,' comments Academy Professor Pa"ivi To"rma". The large number of photons in the beam allows clear observation
of the distribution of photons at different energies that was predicted
by Bose and Einstein, as shown in the figure. 'The brightness of the
beam makes it easier to explore new areas of fundamental research and applications with these condensates,' she continues. An invention that
emerged from the condensate research of the group has just been granted
a patent and will be developed further.


========================================================================== Story Source: Materials provided by Aalto_University. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Aaro I. Va"keva"inen, Antti J. Moilanen, Marek Nečada, Tommi K.

Hakala, Konstantinos S. Daskalakis, Pa"ivi To"rma". Sub-picosecond
thermalization dynamics in condensation of strongly coupled
lattice plasmons. Nature Communications, 2020; 11 (1) DOI:
10.1038/s41467-020- 16906-1 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200622095029.htm

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