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In experiments on nanoscale systems, Heisenberg�s uncertainty
principle sometimes blocks scientists from observing the Fano effect,
Govorov explained. The interaction of the nanoscale system and its
continuum state surroundings can�t be detected.
But in a new high-resolution laser spectroscopy experiment led by M.
Kroner and K. Karrai of the Center of NanoScience at the
Ludwig-Maximilians University in Munich, Germany, scientists utilized
a new method. They measured photons scattered from a single quantum
dot while increasing the laser intensity to saturate the dot�s optical
absorption. This allowed them to observe very weak interactions,
signaled by the appearance of the Fano effect, for the first time.
A theory for the new nonlinear method was developed by Govorov. �Our
theory suggests that the nonlinear Fano effect and the method
associated with it can be potentially applied to a variety of physical
systems to reveal weak interactions,� he said.
Scientists also can revisit older experiments on atoms by using modern
tools such as highly coherent light sources that are strong enough to
reveal such nonlinear Fano-effects, Karrai said. �We can explore new
frontiers in quantum optics,� he noted.
The researchers were funded by the National Science Foundation (USA),
SFB 631 (Germany), A. von Humboldt Foundation (Germany), Engineering
and Physical Sciences Research Council (UK), SANDiE (EU), Royal
Society of Edinburgh, German Excellence Initiative via the Nanosystems
Initiative Munich (NIM), and Ohio University�s Nanobiotechnology
Initiative.
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