arXiv subjects

Nithesh Balasubramanian

Publications and source records attributed to Nithesh Balasubramanian.

4 recordsLinked to original sources

arXiv2025

A cold beam of BaOH molecules using a water-vapour seeded neon gas

In this paper we report on the production and characterization of a cold beam of BaOH molecules using a cryogenic buffer-gas beam source. BaOH is a highly suitable molecule for studies of the violation of fundamental symmetries, such as the search for the electron's electric dipole moment. BaOH molecules are synthesised inside the cold source through laser ablation of a barium metal target while water vapor is seeded into the neon buffer gas. The BaOH flux is significantly enhanced ($\sim$11 times) when laser-exciting the barium atoms inside the buffer-gas cell on the $^1\mathrm S_0 - ^3\mathrm P_1$ transition. A similar enhancement has been reported for other alkaline-earth(-like) monohydroxides. For typical source conditions, the molecular beam has an average velocity of $\approx180$ m/s and an intensity of $\sim 10^{9}$ molecules s$^{-1}$ in $N=1$, which is comparable to that of cryogenic BaF beams.

physics.atom-ph↗

arXiv2025

2D transverse laser cooling of a hexapole focused beam of cold BaF molecules

A cryogenic buffer gas beam, an electrostatic hexapole lens, and 2D transverse Doppler laser cooling are combined to produce a bright beam of barium monofluoride ($^{138}$Ba$^{19}$F) molecules. Experimental results and trajectory simulations are used to study the laser cooling effect as a function of laser detuning, laser power, laser alignment, and interaction time. A scattering rate of 6.1(1.4) $\times 10^{5}$ s$^{-1}$ on the laser cooling transition is obtained; this is $14 \%$ of the expected maximum, which is attributed to limited control of the magnetic field used to remix dark states. Using 3 tuneable lasers with appropriate sidebands and detuning, each molecule scatters approximately 400 photons during 2D laser cooling, limited by the interaction time and scattering rate. Leaks to dark states are less than 10$\%$. The experimental results are used to benchmark the trajectory simulations to predict the achievable flux 3.5 m downstream for a planned $e$EDM experiment.

physics.atom-ph↗

arXiv2025

Prospects for measuring the electron's electric dipole moment with polyatomic molecules in an optical lattice

We present the conceptual design of an experiment to measure the electron's electric dipole moment (eEDM) using $^{138}$BaOH molecules in an optical lattice. The BaOH molecule is laser-coolable and highly sensitive to the eEDM, making it an attractive candidate for such a precision measurement, and capturing it in an optical lattice offers potentially very long coherence times. We study possibilities and limitations of this approach, identify the most crucial limiting factors and ways to overcome them. The proposed apparatus can reach a statistical error of $10^{-30}\,e\,$cm by measuring spin precession on a total number of $5 \times 10^9$ molecules over a span of 120 days.

physics.atom-ph↗

arXiv2023

Mass and Shape Determination of Optically Levitated Nanoparticles

When introducing a nanoparticle into an optical trap, its mass and shape are not immediately apparent. We combine a charge-based mass measurement with a shape determination method based on light scattering and an analysis of the damping rate anisotropy, all on the same set of silica nanoparticles, trapped using optical tweezers in vacuum. These methods have previously only been used separately, and the mass determination method has not been applied to asymmetric particles before. We demonstrate that the combination of these classification techniques is required to distinguish particles with similar mass but different shape, and vice versa. The ability to identify these parameters is a key step for a range of experiments on precision measurements and sensing using optically levitated nanoparticles.

physics.optics↗