arXiv subjects

V. V. Gromyko

Publications and source records attributed to V. V. Gromyko.

3 recordsLinked to original sources

arXiv2026

Three-dimensional three-photon Stark spectroscopy of a single Rb Rydberg atom in an ultrahigh-vacuum glass cell with eight electrodes

Quantum computing and quantum simulation with ultracold neutral atoms require Rydberg excitation of individual atoms in atomic arrays. Rydberg states are extremely sensitive to external electric fields, therefore precise three-dimensional control of the electric field is essential. We performed a spectroscopic study of three-photon Rydberg excitation of a single Rb atom in an optical dipole trap in the presence of an external DC electric field. The field was generated by eight electrodes deposited on the inner surfaces of an ultrahigh-vacuum glass cell. The used three-photon scheme of laser excitation of Rydberg \textit{nP} states allows the Stark shift and the splitting of the resonances to be observed simultaneously, which simplifies calibration of the electric field. In addition, in the commonly used two-photon Rydberg excitation schemes, the light shifts can complicate accurate determination of the DC Stark shift, particularly when the external electric field is scanned across different spatial directions, and different Stark components are excited. These shifts are absent in the three-photon excitation scheme used in our experiment. We demonstrated the ability to independently tune the electric field along all three spatial directions and to compensate for stray electric fields. The measured three-photon spectra exhibit Stark shifts and splittings of the three-photon resonance that are in good agreement with theoretical calculations. These results are also of interest for Rydberg electrometry.

physics.atom-ph↗

arXiv2026

Numerically optimized amplitude-robust controlled-Z gate for ultracold neutral atoms with individual addressing capability

We numerically optimized a scheme for a neutral atom Rydberg blockade symmetric controlled-Z (CZ) gate to increase its robustness to variations in the Rabi frequency. This gate scheme uses analytically defined phase profiles of the laser pulse and demonstrates increased robustness to variations in the Rabi frequency almost by an order of magnitude compared to previous proposals. We demonstrate the applicability of our gate protocol to individual addressing in Rydberg excitation, taking into account the asymmetry of Rabi frequencies for two atoms that are individually excited by tightly focused laser beams. This allows for reducing the effects of residual thermal motion of trapped atoms and beam pointing instability on gate fidelities. We investigated the performance of our gate protocol for single-photon and two-photon Rydberg excitation schemes and showed its advantages for individual addressing at finite temperatures of trapped atoms.

quant-ph↗

arXiv2024

High-Fidelity Individual Addressing of Single Atoms in Quantum Registers at Three-Photon Laser Excitation of Rydberg States

Precise individual addressing of single atoms in quantum registers formed by optical trap arrays is essential to achieve high-fidelity quantum gates in neutral-atom quantum computers and simulators. Two-qubit quantum gates are typically realized using coherent two-photon laser excitation of atoms to strongly interacting Rydberg states. However, two-photon excitation encounters challenges in individual addressing with tightly focused laser beams due to atom position uncertainty and the spatial inhomogeneity in both Rabi frequencies and light shifts. In this work, we theoretically demonstrate that the fidelity of individual addressing can be improved by employing coherent three-photon laser excitation of Rydberg states. For a specific example of $5s_{1/2}\!\xrightarrow{Ω_1}\!5p_{3/2}\!\xrightarrow{Ω_2}\!6s_{1/2}\!\xrightarrow{Ω_3}\!np$ excitation in $^{87}$Rb atoms, we find that upon strong laser coupling in the second step (Rabi frequency $Ω_2$) and moderate coupling in the first and third steps (Rabi frequencies $Ω_1$ and $Ω_3$), the three-photon Rabi frequency is given by $Ω\!=\!Ω_1Ω_3/Ω_2$. If the spatial distributions of $(Ω_1Ω_3)$ and $Ω_2$ are arranged to be identical, $Ω$ becomes independent of atom position, even within very tightly focused laser beams. This approach dramatically improves individual addressing of Rydberg excitation for neighboring atoms in trap arrays compared to conventional two-photon excitation schemes. Our findings are crucial for large-scale quantum registers of neutral atoms, where distances between adjacent atoms should be minimized to ensure stronger Rydberg interactions and compact arrangement of atom arrays.

quant-ph↗