arXiv subjects

J. H. Iacoponi

Publications and source records attributed to J. H. Iacoponi.

3 recordsLinked to original sources

arXiv2026

Nanoparticle arrays levitated in a cavity for quantum sensing

Levitated nanoparticles are being investigated as ultrasensitive quantum sensors of forces and accelerations, with applications ranging from fundamental physics phenomena such as dark matter or quantum gravity to real world applications. Attention is now turning to multiparticle regimes, and an important question is whether collective effects offer advantages for sensing. We investigate here the spectral characteristics of collective motion of $N $ trapped nanoparticles interacting via the optical mode of a cavity. We find the collective motion typically exhibit two generic spectral features: a broad spectral feature, the collective bright mode (CBM) which has been previously studied; but we find also a new structure of sharp peaks , the mechanical mode comb (MMC). We can describe all the detailed spectral features of the system, with a simple closed-form expression, by reducing the motion to a 1D generic collective mode which is non-Hermitian. We show that the MMC is more advantageous than the usual CBM for increased sensitivity in force sensing. We find that the mechanical comb can autonomously repair loss of `teeth' due to particle loss, a feature that may offer robustness in sensing.

physics.optics↗

arXiv2023

Sensing microscopic directional noise baths with an optically cooled and levitated nanoparticle

Optomechanical devices are being harnessed as sensors of ultraweak forces for applications ranging from inertial sensing to the search for the elusive dark matter. For the latter, there is a focus on detection of either higher energy single recoils or ultralight, narrowband sources; a directional signal is expected. However, the possibility of searching for a stochastic stream of weak impulses, or more generally a directional broadband signal, need not be excluded; with this and other applications in mind, we investigate the experimental signature of Gaussian white noise impulses with a well defined direction $Ψ$ on a levitated nanosphere, trapped and 3D cooled in an optical tweezer. We find that cross-correlation power spectra offer a calibration-free distinctive signature of the presence of a directional but stochastic microscopic force and its orientation quadrant, unlike normal power spectral densities (PSDs). We obtain excellent agreement between theoretical and experimental results. With calibration we are able to measure the angle $Ψ$, akin to a force compass in a plane. We discuss prospects for extending this technique into quantum regime and compare the expected behaviour of quantum baths and classical baths.

physics.optics↗

arXiv2022

Controlling mode orientations and frequencies in levitated cavity optomechanics

Cavity optomechanics offers quantum cooling, quantum control and measurement of small mechanical oscillators. However the optical backactions that underpin quantum control can significantly disturb the oscillator modes: mechanical frequencies are shifted by the optical spring effect and light-matter hybridisation in strong coupling regimes; mechanical modes hybridise with each other via the cavity mode. This is even more pertinent in the field of levitated optomechanics, where optical trapping fully determines the mechanical modes and their frequencies. Here, using the coherent-scattering (CS) set-up that allowed quantum ground state cooling of a levitated nanoparticle, we show that -- when trapping away from a node of the cavity standing wave -- the CS field opposes optical spring shifts and mechanical mode hybridisation. At an optimal cancellation point, independent of most experimental parameters, we demonstrate experimentally that it is possible to strongly cavity cool and control the {\em unperturbed} modes. Suppression of the cavity-induced mode hybridisation in the $x-y$ plane is quantified by measuring the $S_{xy}(ω)$ correlation spectra which are seen to always be anti-correlated except at the cancellation point where they become uncorrelated. The findings have implications for directional force sensing using CS set-ups.

quant-ph↗