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SUMMARY:Suppression of Spin Projection Noise in Broadband Atomic Magnetome
 try - Dr Koschorrreck (ICFO Barcelona)
DTSTART:20100302T140000Z
DTEND:20100302T150000Z
UID:TALK23385@talks.cam.ac.uk
CONTACT:6270
DESCRIPTION:We demonstrated reduction of quantum fluctuations by creating 
 \nmacroscopic entanglement in an ensemble of 7 × 10^5 rubidium 87 atoms \
 nvia optical quantum non-demolition measurements. Intrinsic quantum \nfluc
 tuations of a coherent spin state were reduced by 2.9 dB. The \nmetrologic
 al precision of a broad-band magnetometer was improved beyond \nthe standa
 rd-quantum limit by 2.0 dB.\nThe major steps toward this first successful 
 realization of spin \nsqueezing in a magnetically sensitive system with MH
 z-bandwidth are \ndiscussed. First\, a magnetic field imaging technique wa
 s developed to \nmonitor the magnetic field environment of the atomic ense
 mble. The \ntechnique has sensitivities down to sub-microGauss at 100um sp
 atial \nresolution. It reveals intrinsically both the magnitude and the \n
 direction of the magnetic field. Second\, we establish a technique to \nov
 ercome fundamental limitations in the dispersive spin measurement in \nmul
 ti-level atoms\, caused by tensorial light shifts. Third\, we use a \nmaxi
 mally mixed state as noise reference to calibrate the quantum \nnon-demoli
 tion measurement reliably.\n
LOCATION:Rutherford building\, Seminar Room B
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