Characterizing smartphone capabilities for seismic and structural monitoring.

As seismic events continue to pose significant threats to urban infrastructure, leveraging smartphones equipped with accelerometers for real-time monitoring has gained prominence. To ascertain the reliability and sensitivity of smartphone-based measurements, an in-depth characterization of their response is essential. This article presents a thorough characterization of the performance of typical accelerometers installed on three distinct smartphone models.

Quantum Signature of a Squeezed Mechanical Oscillator.

Recent optomechanical experiments have observed nonclassical properties in macroscopic mechanical oscillators. A key indicator of such properties is the asymmetry in the strength of the motional sidebands produced in the probe electromagnetic field, which is originated by the noncommutativity between the oscillator ladder operators. Here we extend the analysis to a squeezed state of an oscillator embedded in an optical cavity, produced by the parametric effect originated by a suitable combination of optical fields.

Imaging Correlations in Heterodyne Spectra for Quantum Displacement Sensing.

The extraordinary sensitivity of the output field of an optical cavity to small quantum-scale displacements has led to breakthroughs such as the first detection of gravitational waves and of the motions of quantum ground-state cooled mechanical oscillators. While heterodyne detection of the output optical field of an optomechanical system exhibits asymmetries which provide a key signature that the mechanical oscillator has attained the quantum regime, important quantum correlations are lost. In turn, homodyning can detect quantum squeezing in an optical quadrature but loses the important sideband asymmetries.