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n-EDM Collaboration Meeting: Precision Magnetometry Alex Sushkov and Dima Budker Berkeley. UIUC, December 2-3, 2004. Linear Polarization. Medium. . Circular Components. Magnetic Field. The Concept. Commercial dense flint glasses: V~3 10 -5 rad/G/cm
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n-EDM Collaboration Meeting:Precision MagnetometryAlex Sushkov and Dima Budker Berkeley UIUC, December 2-3, 2004
Linear Polarization Medium Circular Components Magnetic Field The Concept • Commercial dense flint glasses: V~310-5 rad/G/cm • Atomic vapor (very-high vacuum): V~104 rad/G/cm • ~1020 greater rotation "per atom"
Cold Atomic Magnetometer • Expected B-field from 3He spins: B ~ 2×1012 • 10-20/2000 • 2.1 • 8 ~ 2×10-10 G • State-of-the-art SQUIDs ~ 3×10-11 G/Hz1/2at 4 K • Demonstrated warm atomic magnetometers ~ 10-11 G/Hz1/2 • The goal for the cold Ag magnetometer: B-field sensitivity ~ 10-12 G/Hz1/2 or better and operation around 4 K • This corresponds to spin-relaxation time of ~ 30 seconds • Spin-relaxation times around 60 seconds have been indirectly observed [Yabuzaki]
Quantum Non-Demolition and Spin-Squeezing • How do the noise properties of an atomic magnetometer or an EDM experiment scale with the number N of the species under study? • 1/√N? • Fundamental noise sources for an atomic magnetometer: • quantum projection noise • photon shot-noise • For short measurement times (τ « τrel/√N), the optimal sensitivity scales as N-3/4 • But at longer measurement times (τ ~ τrel) the optimal sensitivity scales as 1/√N, as for a usual shot-noise limited system • If strongly squeezed probe light is used, the Heisenberg limit may, in principle, be reached for very short measurement times, but once again the 1/√N scaling is restored for τ ~ τrelM. Auzinsh, D. Budker D. F. Kimball, S. M. Rochester, J. E. Stalnaker, A. O. Sushkov, and V. V. Yashchuk, Phys. Rev. Lett.93(17), 173002 (2004); physics/0403097 .