arXiv subjects

Akshay Sawhney

Publications and source records attributed to Akshay Sawhney.

5 recordsLinked to original sources

arXiv2026

Laser Cooling and Hyperfine Measurements of Radium-225 Ions

$^{225}$Ra$^+$ ions (nuclear spin $I=1/2$) have transitions that are first-order insensitive to magnetic field noise, which is advantageous for optical clocks and quantum information science. We report on laser cooling and trapping of $^{225}$Ra$^+$ ions and hyperfine splitting measurements of the ion's $\mathrm{7s}$ $^2\mathrm{S}_{1/2}$, $\mathrm{7p}$ $^2\mathrm{P}_{1/2}$, and $\mathrm{6d}$ $^2\mathrm{D}_{3/2}$ states. We measured the ground state hyperfine constant, $A(\mathrm{S}_{1/2}) =$ $-27.684511052(5)$ $\mathrm{GHz}$, and the quadratic Zeeman coefficient, $C_2 =$ $142.3(1.0)$ $\mathrm{Hz\ G}^{-2}$, of the $^2\mathrm{S}_{1/2} (F=0, m_F = 0) \leftrightarrow~^2\mathrm{S}_{1/2} (F=1, m_{F} = 0)$ transition. Our result addresses a discrepancy in the literature for the ground state hyperfine splitting. We measured the hyperfine constants of the $^2\mathrm{P}_{1/2}$ state, $A(\mathrm{P}_{1/2}) =$ $-5.447(4)$ $\mathrm{GHz}$, and the $^2\mathrm{D}_{3/2}$ state, $A(\mathrm{D}_{3/2}) =$ $-619.7(1.1)$ $\mathrm{MHz}$. We also performed state preparation and measurement using the ground state hyperfine levels and realized a fidelity of $0.9951(9)$.

physics.atom-ph↗

arXiv2026

Graduate Training in Quantum Information Science and Engineering: Lessons, Challenges, and a Roadmap from the NSF Research Traineeship Programs

Since 2019, eighteen NSF Research Traineeship (NRT) awards in quantum information science and engineering (QISE) and adjacent fields have been funded, constituting the largest NSF-coordinated investment in graduate QISE training in the United States. Synthesizing lessons from our programs, we work through the central tensions that every QISE graduate program must negotiate: between depth in a home discipline and breadth across the field, between structured instruction and open-ended experiential and hands-on learning, and between training individual specialists and cultivating teams that collectively cover all areas of QISE. We describe the structural and pedagogical innovations the NRT programs have developed in response, assess what is working and what remains unresolved, and sketch 12 open problems the community will need to address as QISE graduate education scales beyond the well-resourced research universities where it has up till now been mainly concentrated. Eight concrete recommendations follow: (1) adopt the startup model of team-based training as an organizing philosophy; (2) invest immediately in sensing and communication curriculum development; (3) build student agency into program governance, not just activities; (4) establish structural mechanisms for industrial engagement rather than depending on goodwill; (5) design for sustainability from year one; (6) develop graduate-level textbooks spanning all three QISE pillars: computing, sensing, and communications; (7) establish shared outcome assessment instruments across programs; and (8) develop structured mechanisms for faculty professional development in QISE.

physics.ed-ph↗

arXiv2025

Lifetimes of the Metastable $6\mathrm{d}\, ^{2}\mathrm{D}_{5/2}$ and $6\mathrm{d}\, ^{2}\mathrm{D}_{3/2}$ States of Ra$^+$

We report lifetime measurements of the metastable $6\mathrm{d}\, ^{2}\mathrm{D}_{5/2}$ and $6\mathrm{d}\, ^{2}\mathrm{D}_{3/2}$ states of Ra$^+$. The measured lifetimes, $τ_{5} = $ 303.8(1.5) ms and $τ_{3} = $ 642(9) ms, are important for optical frequency standards and for benchmarking high-precision relativistic atomic theory. Independent of the reported measurements, the D state lifetimes were calculated using the coupled-cluster single double triple method, in which the coupled-cluster equations for both core and valence triple excitations were solved iteratively. The method was designed for precise prediction of atomic properties, especially for heavy elements, where relativistic and correlation corrections become large, making their treatment more challenging. This Letter presents the first tests of the method for transition properties. Our prediction agrees with experimental values within the uncertainties. The ability to accurately predict the atomic properties of heavy elements is important for many applications, from tests of fundamental symmetries to the development of optical clocks.

physics.atom-ph↗

arXiv2025

Spectroscopy of electric dipole and quadrupole transitions in $^{224}$Ra$^+$

We report on spectroscopy of the low-lying electronic transitions in $^{224}$Ra$^+$. The ion's low charge to mass ratio and convenient wavelengths make $^{224}$Ra$^+$ a promising optical clock candidate. We measured the frequencies of the the $^2{S}_{1/2} \ $$\leftrightarrow$$\ ^2{P}_{1/2}$ cooling transition, the $^2{S}_{1/2}\ $$\leftrightarrow$$\ ^2{D}_{5/2}$ clock transition, the $^2{D}_{3/2} \ $$\leftrightarrow$$\ ^2{P}_{3/2}$ electric dipole transition, and the $^2{D}_{5/2} \ $$\leftrightarrow$$\ ^2{P}_{3/2}$ cleanout transition. From these measurements we calculate the frequencies of the $^2{D}_{3/2}\ $$\leftrightarrow$$\ ^2{P}_{1/2}$ repump transition, the $^2{S}_{1/2} \ $$\leftrightarrow$$\ ^2{D}_{3/2}$ electric quadrupole transition, and the $^2{S}_{1/2} \ $$\leftrightarrow$$\ ^2{P}_{3/2}$ electric dipole transition.

physics.atom-ph↗

arXiv2018

The influence of sublattice bias on superfluid to Mott insulator transitions

We model the superfluid to Mott insulator transition for a Bose gas on a lattice with two inequivalent sublattices. Using the Gutzwiller ansatz, we produce phase diagrams and provide an understanding of the interplay between superfluidity on each sublattice. We explore how the Mott lobes split, and describe the experimental signatures.

cond-mat.quant-gas↗