Making larger numbers count more

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Science  11 Jul 2014:
Vol. 345, Issue 6193, pp. 176-177
DOI: 10.1126/science.345.6193.176-f

Some measurements make better use of a larger number of particles than others. To make very precise measurements, physicists often increase the number of particles they use as probes—the more particles, the more precise the measurement. Sewell et al. sent light pulses through a cloud of 87Rb atoms to measure the spin alignment of the atomic cloud. They found that the precision of the measurement grew more quickly as the number of photons was increased than it does when more conventional methods are employed. The key to this improvement was making an indirect measurement in which the output was a nonlinear function of the number of photons used.

Phys. Rev. X 4, 021045 (2014).

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