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SUMMARY:Backaction and entanglement in microwave optomechanics
DTSTART:20181123T110000
DTEND:20181123T120000
DTSTAMP:20260510T202418Z
UID:e5f7c70e5d02d6c20815facb232429cb35a7768db793ca1d77900f42
CATEGORIES:Conferences - Seminars
DESCRIPTION:Mika Sillanpää\, Aalto University\, Quantum Nanomechanics/ L
 TL\, Finland\nThe interplay of measurement imprecision and quantum backact
 ion limits the sensitivity with which the position of an oscillator can be
  continuously monitored\, to be at best equal to the oscillator’s zero-p
 oint fluctuations. However\, any single quadrature of the motion can\, in 
 principle\, be measured without limit\, provided that the measurement back
 action is shunted to the orthogonal quadrature. Such backaction evading (B
 AE) measurements\, which are examples of quantum nondemolition measurement
 s\, can be achieved by appropriately synchronizing the measurement with th
 e oscillator’s intrinsic motion. In our work\, we study the collective m
 odes of two uncoupled mechanical oscillators\, each independently coupled 
 to a microwave cavity. The oscillators are realized as aluminum drumheads.
  We carry out a mechanical two-mode BAE measurement of the collective quad
 ratures\, and achieve an evasion of quantum backaction\, caused by microwa
 ve shot noise\, below the backaction arising in a continuous position meas
 urement. The canonically conjugate quadrature is heated predominantly by t
 he quantum backaction. On top of this\, the work realizes the concept of q
 uantum-mechanics-free subsystem. By perturbing the measurement slightly (i
 .e.\, reservoir engineering)\, such measurements can be used to generate s
 tabilized entanglement between two macroscopic mechanical oscillators. Thi
 s prepares a canonical entangled state known as the two-mode squeezed stat
 e. It corresponds to the variances of collective position and momentum qua
 dratures being reduced below the quantum zero-point fluctuations level. We
  carry out such a measurement\, and infer the existence of entanglement in
  the steady state by combining measurements of correlated mechanical fluct
 uations with an analysis of the microwaves emitted from the cavity.\n 
LOCATION:CE 1 3 https://plan.epfl.ch/?room==CE%201%203
STATUS:CONFIRMED
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