arXiv subjects

Youngju Cho

Publications and source records attributed to Youngju Cho.

4 recordsLinked to original sources

arXiv2026

High-fidelity entanglement of polar molecules by dynamic geometric control

In quantum information systems made of optical tweezer arrays of ultracold molecules, thermal motion of molecules degrades the coherence of their interactions, which limits entanglement fidelity and the concomitant scientific applicability of these systems. We show that by controlling the geometry of the dipolar interaction, even when a molecule occupies many motional states in the tweezer, coherence can be preserved. We characterize several geometries that suppress sensitivity to thermal fluctuations. We further use programmable, coherence-preserving motion of the molecules during entanglement to refocus dephasing from relative positional jitter of the tweezers, which is relevant even on the 10 nm scale. These methods yield substantially improved dipolar coherence and enable generation of two-molecule entanglement with a Bell state fidelity of $\mathcal{F}= 0.976^{+0.008}_{-0.011}$ in directly laser-cooled molecules.

physics.atom-ph↗

arXiv2026

Spectroscopy of the $\mathbf{X^2\Sigma^+(v=2) \rightarrow A^2\Pi_{1/2}(v=1)}$ Transition in MgF: Hyperfine Structures and Spectroscopic Constants

We report spectroscopic results of the $X^2\Sigma^+(v=2) \rightarrow A^2\Pi_{1/2}(v=1)$ transition in magnesium monofluoride (MgF). Using Doppler-free Laser-Induced Fluorescence (LIF) spectroscopy on the $X^2\Sigma^+(v=2) \rightarrow A^2\Pi_{1/2}(v=1)$ transition, we resolved 47 hyperfine components distributed over 11 transition lines in X and A states. An effective Hamiltonian -- comprising contributions from vibrational, rotational, $\Lambda$-doubling, and hyperfine interactions -- was presented to model the energy structure of the $A^2\Pi_{1/2}(v=1)$ state. The spectroscopic parameters, including the rotational constant, the $\Lambda$-doubling parameter, and the hyperfine interaction constants, were extracted using a least-square fitting and Markov Chain Monte Carlo (MCMC) procedure. Our study reveals that the spectroscopic constants show subtle changes compared to the $A^2\Pi_{1/2}(v=0)$ state. These results provide critical spectroscopic benchmarks for optimizing optical cycling schemes in MgF, thereby advancing optical cycling efficiency in the magneto-optical trapping of MgF.

physics.atom-ph↗

arXiv2025

Accelerating LLM Inference with Precomputed Query Storage

Large language model (LLM) inference often suffers from high latency, particularly in resource-constrained environments such as on-device or edge deployments. To address this challenge, we present StorInfer, a novel storage-assisted LLM inference system that accelerates response time by precomputing and storing predictable query-response pairs offline. When a user query semantically matches a precomputed query, StorInfer bypasses expensive GPU inference and instantly returns the stored response, significantly reducing latency and compute costs. To maximize coverage and effectiveness, StorInfer employs an LLM-driven generator that adaptively produces diverse and deduplicated queries based on a given knowledge base. This is achieved via two techniques: adaptive query masking, which prevents regeneration of similar queries, and adaptive sampling, which dynamically tunes generation parameters to promote semantic diversity. The resulting query-response pairs are embedded and indexed using a disk-backed vector database to enable fast, similarity-based retrieval at runtime. Using this approach, we generated 150K unique precomputed pairs (taking up to 830 MB of storage space), achieving up to 17.3% latency reduction with no loss in response quality. Our evaluation across multiple QA datasets demonstrates the practicality and scalability of storage-assisted inference, especially in scenarios with predictable query distributions. StorInfer highlights a promising direction in leveraging storage as a primary enabler for efficient, low-latency LLM deployment.

cs.DC↗

arXiv2025

Optical cycling of MgF molecules within the hyperfine states in X(N=1) state

We investigated the optical cycling effect of the $\mathrm{X}^2\Sigma(v=0,\ N=1^-) - \mathrm{A}^2\Pi_{1/2}(v'=0,\ J'=1/2^+)$ band of MgF molecules, specifically the $\mathrm{P_1/Q_{12}(1)}$ transition, which serves as the main transition in the quasi-closed cycling scheme for the laser cooling. A higher number of scattered photons was observed when all three frequency components of the $\mathrm{P_1/Q_{12}(1)}$ transition were simultaneously applied using acousto-optic modulators (AOMs). Optimal conditions were identified by scanning the detuning of frequency components, the laser beam power ratio, and the total laser beam power, and the results were confirmed through rate equation simulations. Under these optimized conditions, and with an applied magnetic field, the scattering rate was enhanced by approximately a factor of six. These results refine the implementation of optical cycling in MgF and lay the groundwork for laser slowing and magneto-optical trapping (MOT) experiments.

physics.atm-clus↗