169 research outputs found
Spontaneous Symmetry Breaking in Two Coupled Nanomechanical Electron Shuttles
We present spontaneous symmetry breaking in a nanoscale version of a setup
prolific in classical mechanics: two coupled nanomechanical pendulums. The two
pendulums are electron shuttles fabricated as nanopillars and placed between
two capacitor plates in a homogeneous electric field. Instead of being
mechanically coupled through a spring they exchange electrons, i.e. they
shuttle electrons from the source to the drain 'capacitor plate'. Nonzero DC
current through this system by external AC excitation is caused via dynamical
symmetry breaking. This symmetry-broken current appears at sub- and
superharmonics of the fundamental mode of the coupled system
Shock Waves in Nanomechanical Resonators
The dream of every surfer is an extremely steep wave propagating at the
highest speed possible. The best waves for this would be shock waves, but are
very hard to surf. In the nanoscopic world the same is true: the surfers in
this case are electrons riding through nanomechanical devices on acoustic waves
[1]. Naturally, this has a broad range of applications in sensor technology and
for communication electronics for which the combination of an electronic and a
mechanical degree of freedom is essential. But this is also of interest for
fundamental aspects of nano-electromechanical systems (NEMS), when it comes to
quantum limited displacement detection [2] and the control of phonon number
states [3]. Here, we study the formation of shock waves in a NEMS resonator
with an embedded two-dimensional electron gas using surface acoustic waves. The
mechanical displacement of the nano-resonator is read out via the induced
acoustoelectric current. Applying acoustical standing waves we are able to
determine the anomalous acoustocurrent. This current is only found in the
regime of shock wave formation. We ontain very good agreement with model
calculations.Comment: 14 Pages including 4 figure
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