Atomic Physics Seminar, Vito Giovanni Lucivero, ICFO, "Quantum metrology with high density atomic vapors and squeezed states of light"

Fri, May 13, 2016, 12:00 pm to 1:30 pm
Jadwin 233
Nowadays there is a considerable progress in optical magnetometry and spin-noise spectroscopy, which use magnetically-sensitive atomic ensembles and optical read-out, approaching fundamental limits. A major outstanding question is whether squeezed light can improve the sensitivity of such atomic sensors under optimal conditions, typically in a high-density regime due to statistical advantage of using more atoms. Here we describe two different experiments: first, we describe an optical magnetometer based on amplitude modulated optical rotation (AMOR), using a 85Rb vapour cell, that achieves room-temperature sensitivity of 70 fT/ √Hz at 7.6 μT and we demonstrate its photon shot-noise-limited (SNL) behaviour from 5 μT to 75μT, making the system a promising candidate for application of squeezed-light. Secondly we describe another apparatus for the detection of spontaneous spin fluctuations of a dense Rb vapour via Faraday rotation of an off-resonance probe beam and we report quantum enhancement of spin noise spectroscopy (SNS) via polarization squeezing of the probe beam up to 3dB over the full density range up to n=1013 atoms cm−3, covering practical conditions used in optimized SNS experiments. We also show that squeezing improves the trade-off between statistical sensitivity and systematic errors due to line broadening, a previously unobserved quantum advantage.