arXiv subjects

Chethn Galla

Publications and source records attributed to Chethn Galla.

3 recordsLinked to original sources

arXiv2026

Trapping of nanofabricated SiO$_2$ high-aspect-ratio discs in an optical lattice

We describe the nanofabrication and loading of lithographically patterned, high aspect ratio $10$ $μ$m diameter silicon dioxide discs with thickness of $400$ nm into an optical standing wave trap in vacuum. We obtain motional spectra of the center of mass motion of the discs using a combination of interferometric and imaging methods. The method is capable of high-efficiency loading and optical trapping using small numbers of objects, of the order of a few particles, with customized geometries and sizes compatible with wafer scale nanofabrication methods. Disc-like particles in optical traps have been identified as promising candidates for detectors of high frequency gravitational waves or as sensitive accelerometers.

physics.optics↗

arXiv2026

Fiber-based scanning levitated nanoparticle force sensor near a metalized membrane

We describe a fiber-based dual-beam trap for dielectric nanospheres with the ability to transfer the trapped particles into a retro-reflective standing-wave trap within micron-range distances of a metallic mirror surface. We illustrate its capability for three dimensional scanning force sensing over a several square micron area of an ultra-thin gold-coated silicon nitride mirror-membrane with a total thickness of approximately 370~nm. We also demonstrate three-dimensional laser feedback cooling and zeptonewton force resolution in high-vacuum at micron range from the membrane, showing promise for future improved tests of gravity at short distances and other surface force investigations. By using charged nanospheres, we expect the method may be useful for studying fluctuating patch potentials and electric field noise in the vicinity of a surface in the $\sim$ kHz to $\sim 100$ kHz frequency regime.

physics.optics↗

arXiv2022

Nanomechanical testing of silica nanospheres for levitated optomechanics experiments

Optically-levitated dielectric particles can serve as ultra-sensitive detectors of feeble forces and torques, as tools for use in quantum information science, and as a testbed for quantum coherence in macroscopic systems. Knowledge of the structural and optical properties of the particles is important for calibrating the sensitivity of such experiments. Here we report the results of nanomechanical testing of silica nanospheres and investigate an annealing approach which can produce closer to bulk-like behavior in the samples in terms of their elastic moduli. These results, combined with our experimental investigations of optical trap lifetimes in high vacuum at high trapping-laser intensity for both annealed and as-grown nanospheres, were used to provide a theoretical analysis of the effects of porosity and non-sphericity in the samples, identifying possible mechanisms of trapping instabilities for nanospheres with non-bulk-silica-like properties.

physics.optics↗