Nils Otterstrom

Nonlinear optical magnetometry with accessible in situ optical squeezing

We demonstrate compact and accessible squeezed-light magnetometry using four-wave-mixing in a single hot rubidium vapor cell. This framework enables 4.7 dB of quantum-noise-reduction while simultaneously adding nonlinear-magneto-optical-rotation(NMOR) signals from the probe and conjugate fields.

Coherence area profiling in multi-spatial-mode squeezed states

The presence of multiple bipartite entangled modes in squeezed states generated by four-wave mixing enables ultra-trace sensing, imaging, and metrology applications that are impossible to achieve with single-spatial-mode squeezed states. For Gaussian seed beams, the spatial distribution of these bipartite entangled modes, or coherence areas, across each beam is largely dependent on the spatial modes present in the pump beam, but it has proven difficult to map the distribution of these coherence areas in frequency and space. We demonstrate an accessible method to map the distribution of the coherence areas within these twin beams. We also show that the pump shape can impart different noise properties to each coherence area, and that it is possible to select and detect coherence areas with optimal squeezing with this approach.

Laser wavelength metrology with color sensor chips.

We present a laser wavelength meter based on a commercial color sensor chip. The chip consists of an array of photodiodes with different absorptive color filters. By comparing the relative amplitudes of light on the photodiodes, the wavelength of light can be determined. In addition to absorption in the filters, etalon effects add additional spectral features which improve the precision of the device. Comparing the measurements from the device to a commercial wavelength meter and to an atomic reference, we found that the device has picometer-level precision and picometer-scale drift over a period longer than a month.