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NEWS

Dr Albert Schliesser

Niels Borh Institute, University of Copenhagen

Friday, January 31st, 2014 at 11:30:00 AM

Conference room Querzoli - LENS - via Nello Carrara 1 - Sesto Fiorentino (Florence)

Published on-line at 12:59:05 PM on Thursday, January 23rd, 2014

Ultralow-noise electro-optomechanical transduction cascade based on a nanomechanical membrane resonator

Electromechanical and optomechanical systems share the underlying physical processes, but the techniques and technologies for perfecting them are rather distinc

Electromechanical and optomechanical systems share the underlying physical processes, but the techniques and technologies for perfecting them are rather distinct. Nonetheless, both platforms, each in  its  own  right,  have  progressed  at  an  extremely  rapid  pace  over  the  last  years,  and  brought  about unprecedented opportunities in sensing of force and displacement, and the manipulation and detection of electromagenetic and/or mechanical quantum states (1). Recently,  a  new  research  frontier has  emerged,  dedicated  to  the  combination  of  electro-  and optomechanical systems (2-4). The benefits of such integrated devices could be manifold, and reach from  the  (near)  noiseless  transduction  of  weak  electronic  signals  into  the  optical  domain  over ultraefficient electrooptic modulators to a fully quantum-coherent conversion cascade of microwave to optical photons (and back), with possible intermediate storage in phononic modes. We  have  developed  and  investigated  a  proof-of-principle  implementation  of  such  an  electro-optomechanical transducer (5). It is based on an ultrahigh-Q silicon nitride membrane resonator (6), which  is  simultaneously  coupled  to  a  degenerate  radio-frequency  (RF)  resonance  circuit,  and  an optical readout mode. By detecting the phase fluctuations imprinted by the membrane on the optical mode with a quantum noise limited imprecision, we can optically measure miniscule voltage signals induced  in  the  RF  circuit.  Among  other analyses,  we  quantify  the  noise  added  in  all  stages  of  the transduction cascade. We find that the membrane thermal noise, and the optical readout noise, both add  as  little  as  60  pV/Hz 1/2 ,  while  the  main  noise  contribution  is  due  the  RF  circuit  itself,  which generates ~800 pV/Hz 1/2  of Johnson noise.  Further improvements of this platform are readily achievable, through more compact integration, improved membrane resonators (e.g. by suppression of phonon tunnelling loss (7)), and RF circuits

with  lower  loss  and/or  temperature.  Looking  further  ahead,  the  investigation  of  hybrid  interference effects—such  as opto/electromechanically  induced  transparency  (OMIT)  (8)  and  the  intimately related mechanically dark modes (9)—appear as an exciting route for further research, in particular with the perspective of quantum state conversion and storage. 

For further informations, please contact Dr Mario Agio.