Strong gate coupling of high-Q nanomechanical resonators.
The detection of mechanical vibrations near the quantum limit is a formidable challenge since the displacement becomes vanishingly small when the number of phonon quanta tends toward zero. An interesting setup for on-chip nanomechanical resonators is that of coupling them to electrical microwave cavities for detection and manipulation. Here we show how to achieve a large cavity coupling energy of up to (2π) 1 MHz/nm for metallic beam resonators at tens of megahertz. We used focused ion beam (FIB) cutting to produce uniform slits down to 10 nm, separating patterned resonators from their gate electrodes, in suspended aluminum films. We measured the thermomechanical vibrations down to a temperature of 25 mK, and we obtained a low number of about 20 phonons at the equilibrium bath temperature. The mechanical properties of Al were excellent after FIB cutting, and we recorded a quality factor of Q ∼ 3 × 10(5) for a 67 MHz resonator at a temperature of 25 mK. Between 0.2 and 2 K we find that the dissipation is linearly proportional to the temperature.
Low Temperature Laboratory, Aalto University, P.O. Box 15100, FI-00076 Aalto, Finland.
Jaakko
J
Sulkko
Mika A
MA
Sillanpää
Pasi
P
Häkkinen
Lorenz
L
Lechner
Meri
M
Helle
Andrew
A
Fefferman
Jeevak
J
Parpia
Pertti J
PJ
Hakonen