arXiv subjects

Ya-Nan Lv

Publications and source records attributed to Ya-Nan Lv.

4 recordsLinked to original sources

arXiv2026

Coherent Molecular Deceleration via Vibrational Bichromatic Force

We propose a scheme for direct laser deceleration of molecules based on a vibrational transition-mediated bichromatic force (VBCF). By precisely engineering mid-infrared optical fields, we establish coherent absorption-stimulated emission cycles while exploiting the long lifetime of vibrational excited states to suppress spontaneous decay and decoherence, rendering the deceleration process effectively non-dissipative. Unlike schemes based on electronic transitions, our approach completely circumvents the restrictive Franck-Condon factors. Using the fundamental vibrational transition of $^{13}$CO$_2$ as a test case, we achieve a deceleration of $1.45\times 10^5$~m/s$^2$ with negligible population loss over the full interaction time. This VBCF framework provides a general route to cold molecules applicable to any species with an allowed fundamental vibrational transition, opening broad prospects in cold chemistry and quantum metrology.

physics.atom-ph↗

arXiv2026

Synthetic Gauge Phase in Rydberg Electromagnetically Induced Transparency

We demonstrate a synthetic gauge phase in Rydberg electromagnetically induced transparency (EIT) using room-temperature rubidium vapor. By exploiting polarization selection rules in a ladder-type system involving ground, intermediate, and Rydberg states, multiple Zeeman sublevels form closed-loop transitions that acquire a gauge phase. We show that the relative polarization angle between the linearly polarized probe and coupling lasers directly controls this gauge phase, which modulates the EIT transmission and Rydberg state population, consequently controlling the linewidth of EIT due to Rydberg dipole-dipole interactions between atoms. Our approach provides a simple polarization-based method for realizing synthetic gauge physics and manipulating many-body interactions in atomic ensembles without requiring laser cooling and dipole traps.

physics.atom-ph↗

arXiv2024

Fundamental limits of free-space microwave-to-optical frequency conversion efficiency using Rydberg atoms

Efficient microwave-to-optical frequency conversion (MOC) is crucial for applications such as radiometry, electrometry, quantum microwave illumination and quantum networks. Rydberg atoms provide a unique platform for realizing free-space MOC, promising wide-bandwidth, scalable, and flexible quantum interfaces. Here, we develop a theoretical framework to evaluate the system conversion efficiency, accounting for the mismatch between microwave and optical wavelengths comparing with the atomic ensemble size. Our analysis reveals that the conversion efficiency is fundamentally limited by the focusing of the free-space microwave field, with an upper bound of about 3/16 for diffraction-limited focusing. We propose using a microwave near-field antenna to overcome this limit. Our work provides a foundation for assessing and optimizing free-space MOC, paving the way for a variety of applications based on free-space MOC.

quant-ph↗

arXiv2024

Post-selection shifts the transition frequency of helium in an atomic beam

Post-selecting output states in measurements can effectively amplify weak signals and improve precision. However, post-selection effects may also introduce unintended biases in precision measurements. Here, we investigate the influence of post-selection in the precision spectroscopy of the $2^3S - 2^3P$ transition of helium ($^4$He) using an atomic beam. We directly observe that post-selection based on atomic positions causes a shift in the measured transition frequency, amounting to approximately -55 kHz. After accounting for this post-selection shift, we obtain a corrected frequency of $276,764,094,712.45 \pm 0.86$ kHz for the $2^3S_1 - 2^3P_0$ transition. Combining this result with existing data for $^3$He, we derive a new value for the difference in squared nuclear charge radii, $δr^2 [r_{h}^{2} - r_α^{2}] = 1.0733 \pm 0.0021$ fm$^2$. This value shows a $2.8σ$ deviation from measurements of muonic helium ions, potentially pointing to new physics that challenges lepton universality in quantum electrodynamics.

physics.atom-ph↗