Nanoscale vacuum gauge based on second-order coherence in optical levitation

Absolute air pressure measurement based on molecular mechanical collision with an optically levitated nanoparticle can provide high accuracy, but the dephasing processes complicate the extraction of the interactions in levitated oscillator systems. This study overcomes this challenge by performing second-order coherence analysis, enabling independent measurement of energy decoherence rates while eliminating dephasing errors. The nanoscale vacuum gauge achieves precise pressure measurements from atmospheric pressure down to 7 $\ifmmode\times\else\texttimes\fi{}$ 10${}^{\ensuremath{-}6}$ mbar. This demonstrates that mechanical nano-oscillators are promising candidates for precision pressure sensing applications.