The Ars Technica article oversells the shot-noise limit. What you really want to see in this business is a thermally-limited oscillator; the Brownian motion in the spring driving the mass. For a quantum mechanically limited oscillator, check out work like this (which shares an author with the paper linked by Ars Technica):
A shot noise limit is not an inherent reason for kudos. In particular, this sensor is shot-noise limited at frequencies above a few kHz. In this context, the shot-noise limit may only represent the intrinsic noise of the optical readout, not the intrinsic thermal noise of the oscillator. Their noise figure of 10 ug/rtHz is interesting, but not unprecedented.
The Micro-G FG-5X represents the state of the art at low frequency and can do 15 ug/rtHz at sub-Hz frequencies.
For a more-fair comparison, in a standard MEMS form factor, the Analog Devices ADXL 103 and 203 do 110 ug/rtHz at 100s of Hz and below and cost <$10 each.
It'll be way cool to see what their oscillator will do with improvements. Optical readout has less influence on the detector mass and comparable precision to the best capacitive readout.
Awesome. We'd actually have a use in the lab for such a measurement (we see seismic traffic noise from a bridge ~200m away). We've toyed with a magnetometer a bit, but an acceleration-based measurement would be more relevant for our needs.
Did you do any documentation/know of a reference? Thanks!