arXiv subjects

Alisher Duspayev

Publications and source records attributed to Alisher Duspayev.

18 recordsLinked to original sources

arXiv2026

SI-Traceable Calibration and Performance Benchmarking of a Terahertz Photomixer Transmitter-Receiver System Using a Rydberg Atomic Sensor

Accurate calibration of electromagnetic field strength in the terahertz (THz) frequency regime remains challenging due to the limited availability of SI-traceable field sensors. Here we demonstrate SI-traceable calibration and performance benchmarking of a commercial photomixer-based THz transmitter-receiver system operating near 204 GHz using Rydberg electric-field sensing in a thermal atomic vapor. The THz electric field is extracted from the Autler-Townes (AT) effect of the cesium $17D_{5/2}\rightarrow18P_{3/2}$ Rydberg transition. We measure the strength of AT-split lines as a function of THz detuning from resonance to find the on-resonant Rabi frequency, which, together with atomic transition dipole moments and fundamental constants, yields the THz electric field. The atomically measured field calibrates the photomixer transmitter field and power, while simultaneous measurements with a commercial InGaAs photomixer receiver calibrate the receiver's current-to-field responsivity and convert its current-noise floor into an absolute noise-equivalent THz electric-field sensitivity. Our study demonstrates that Rydberg atomic sensors provide a practical method for SI-traceable calibration and benchmarking of THz transmitter and receiver systems, and for the establishment of a quantitative link between state-of-the-art and absolute atom-based THz sensors.

physics.atom-ph↗

arXiv2025

Effects of inert background gases and photo-illumination on three-color electromagnetically induced transparency of rubidium vapor

Three-color Rydberg electromagnetically induced transparency (EIT) of room-temperature Rb vapor in the presence of inert gases (Ar, Ne, and N$_2$) at 50~mTorr and 500~mTorr is investigated. The observed EIT lines shift and develop blue-detuned satellite lines, dependent on inert-gas species and pressure. The separations of the satellite from the main EIT lines are approximately pressure-independent, while their strength increases with inert-gas pressure. The satellite lines are attributed to hyperfine collisions of the intermediate $5D_{3/2}$ state. Further, analyzing the Stark effect of Rydberg levels, it is found that the inert gases suppress static electric fields in the vapor cells, which we induce by photo-illumination of the cell walls with an auxiliary 453-nm laser. In the work, we utilize Rydberg levels with principal quantum numbers $n$ = 25 and 50 and angular momenta $\ell$ = 3 up to 6, excited by the EIT lasers and optional radio-frequency dressing fields. The work is of interest in the spectroscopic study of mixed-species warm vapors, in sensing applications of Rydberg atoms in vapor cells, and in non-invasive electric-field diagnostics of low-pressure discharge plasma.

physics.atom-ph↗

arXiv2025

Filter circuit for suppression of electric-field noise in Rydberg-atom experiments

Rydberg atoms are widely employed in precision spectroscopy and quantum information science. To minimize atomic decoherence caused by dc Stark effect, the electric field noise at the Rydberg atom location should be kept below $\sim 10$ mV/cm. Here we present a simple yet effective electronic circuit, referred to as a clamp switch, that allows one to realize such conditions. The clamp switch enables precise low-noise electric field control while allowing application of fast high-voltage ionization pulses through the same electrode(s), enabling atom detection via electric-field ionization and electron or ion counting. We outline the circuit design and analyze its noise suppression performance for both small and large input signals. In application examples, we employ the clamp switch to reduce the spectral width and increase the signal strength of a Rydberg line by a factor of two, to estimate the electric-field noise in the testing chamber, and to perform electric-field calibration using Rydberg Stark spectroscopy. The clamp switch improves coherence times and spectroscopic resolution in fundamental and applied quantum science research with Rydberg atoms.

physics.atom-ph↗

arXiv2025

Hyperfine structure and collisions in three-photon Rydberg electromagnetically induced transparency

Multi-photon electromagnetically-induced transparency (EIT) of atomic vapors involves several intermediate atomic levels. The sub-structure of these levels and their collisional interactions can drastically alter experimental EIT signals. Here, we report on hyperfine structure and collision effects in three-photon Rydberg EIT on the cascade $5S_{1/2} \rightarrow$ $5P_{1/2} \rightarrow 5D_{3/2}$ $\rightarrow 25F_{5/2}$ in a room temperature $^{85}$Rb vapor cell. In our measurements of EIT spectra, we identify two types of EIT signatures that correspond with distinct excitation pathways and atomic velocity classes in the atomic vapor. The $5D_{3/2}$ hyperfine structure and Autler-Townes splittings lead to complex patterns in the EIT spectra, which we analyze with the aid of 10-level EIT simulations. Adding 50~mTorr of Ar gas alters the EIT spectra and induces an additional, third EIT mode. Based on our simulation results, we attribute these changes to hyperfine collisions in the Rb $5D_{3/2}$ level. Our study may become useful in quantum technologies involving Rydberg EIT and hyperfine collisions in vapor cells, including non-invasive spatio-temporally resolved electric-field sensing of electric fields in low-pressure plasmas.

physics.atom-ph↗

arXiv2024

Terrestrial Very-Long-Baseline Atom Interferometry: Summary of the Second Workshop

This summary of the second Terrestrial Very-Long-Baseline Atom Interferometry (TVLBAI) Workshop provides a comprehensive overview of our meeting held in London in April 2024, building on the initial discussions during the inaugural workshop held at CERN in March 2023. Like the summary of the first workshop, this document records a critical milestone for the international atom interferometry community. It documents our concerted efforts to evaluate progress, address emerging challenges, and refine strategic directions for future large-scale atom interferometry projects. Our commitment to collaboration is manifested by the integration of diverse expertise and the coordination of international resources, all aimed at advancing the frontiers of atom interferometry physics and technology, as set out in a Memorandum of Understanding signed by over 50 institutions.

hep-ex↗

arXiv2024

Rydberg electromagnetically induced transparency of $^{85}$Rb vapor in Ar, Ne and N$_2$ gases

An experimental study on Rydberg electromagnetically induced transparency (EIT) in rubidium (Rb) vapor cells containing inert gases at pressures $\le 5$ Torr is reported. Using an inert-gas-free Rb vapor cell as a reference, we measure frequency shift and line broadening of the EIT spectra in Rb vapor cells with argon, neon or nitrogen gases at pressures ranging from a few mTorr to 5 Torr. The results qualitatively agree with a pseudo-potential model that includes $s$-wave scattering between the Rydberg electron and the inert-gas atoms, and the effect of polarization of the inert-gas atoms by the Rydberg atoms. Our results are important for establishing Rydberg-EIT as an all-optical and non-intrusive spectroscopic probe for field diagnostics in low-pressure radio-frequency discharges.

physics.atom-ph↗

arXiv2024

An optical atomic clock using $4D_J$ states of rubidium

We analyze an optical atomic clock using two-photon $5S_{1/2} \rightarrow 4D_J$ transitions in rubidium. Four one- and two-color excitation schemes to probe the fine-structure states $4D_{3/2}$ and $4D_{5/2}$ are considered in detail. We compare key characteristics of Rb $4D_J$ and $5D_{5/2}$ two-photon clocks. The $4D_J$ clock features a high signal-to-noise ratio due to two-photon decay at favorable wavelengths, low dc electric and magnetic susceptibilities, and minimal black-body shifts. Ac Stark shifts from the clock interrogation lasers are compensated by two-color Rabi-frequency matching. We identify a "magic" wavelength near 1060~nm, which allows for in-trap, Doppler-free clock-transition interrogation with lattice-trapped cold atoms. From our analysis of clock statistics and systematics, we project a quantum-noise-limited relative clock stability at the $10^{-13}/\sqrt{\tau(s)}$-level, with integration time $\tau$ in seconds, and a relative accuracy of $\sim 10^{-13}$. We describe a potential architecture for implementing the proposed clock using a single telecom clock laser at 1550~nm, which is conducive to optical communication and long-distance clock comparisons. Our work could be of interest in efforts to realize small and portable Rb clocks and in high-precision measurements of atomic properties of Rb $4D_J$-states.

physics.atom-ph↗

arXiv2023

High-angular-momentum Rydberg states in a room-temperature vapor cell for DC electric-field sensing

We prepare and analyze Rydberg states with orbital quantum numbers $\ell \le 6$ using three-optical-photon electromagnetically-induced transparency (EIT) and radio-frequency (RF) dressing, and employ the high-$\ell$ states in electric-field sensing. Rubidium-85 atoms in a room-temperature vapor cell are first promoted into the $25F_{5/2}$ state via Rydberg-EIT with three infrared laser beams. Two RF dressing fields then (near-)resonantly couple $25 \ell$ Rydberg states with high $\ell$. The dependence of the RF-dressed Rydberg-state level structure on RF powers, RF and laser frequencies is characterized using EIT. Furthermore, we discuss the principles of DC-electric-field sensing using high-$\ell$ Rydberg states, and experimentally demonstrate the method using test electric fields of $\lesssim$~50~V/m induced via photo-illumination of the vapor-cell wall. We measure the highly nonlinear dependence of the DC-electric-field strength on the power of the photo-illumination laser. Numerical calculations, which reproduce our experimental observations well, elucidate the underlying physics. Our study is relevant to high-precision spectroscopy of high-$\ell$ Rydberg states, Rydberg-atom-based electric-field sensing, and plasma electric-field diagnostics.

physics.atom-ph↗

arXiv2023

Terrestrial Very-Long-Baseline Atom Interferometry: Workshop Summary

This document presents a summary of the 2023 Terrestrial Very-Long-Baseline Atom Interferometry Workshop hosted by CERN. The workshop brought together experts from around the world to discuss the exciting developments in large-scale atom interferometer (AI) prototypes and their potential for detecting ultralight dark matter and gravitational waves. The primary objective of the workshop was to lay the groundwork for an international TVLBAI proto-collaboration. This collaboration aims to unite researchers from different institutions to strategize and secure funding for terrestrial large-scale AI projects. The ultimate goal is to create a roadmap detailing the design and technology choices for one or more km-scale detectors, which will be operational in the mid-2030s. The key sections of this report present the physics case and technical challenges, together with a comprehensive overview of the discussions at the workshop together with the main conclusions.

hep-ex↗

arXiv2023

Rotation Sensing using Tractor Atom Interferometry

We investigate a possible realization of an ultracold-atom rotation sensor that is based on recently proposed tractor atom interferometry (TAI). An experimental design that includes generation of a Laguerre-Gaussian-beam-based "pinwheel" optical lattice and multi-loop interferometric cycles is discussed. Numerical simulations of the proposed system demonstrate TAI rotation sensitivity comparable to that of contemporary matter-wave interferometers. We analyze a regime of TAI rotation sensors in which nonadiabatic effects may hinder the system's performance. We apply quantum optimal control to devise a methodology suitable to address this nonadiabaticity. Our studies are of interest for current efforts to realize compact and robust matter-wave rotation sensors, as well as in fundamental-physics applications of TAI.

physics.atom-ph↗

arXiv2023

Spectroscopy of the $^{85}$Rb 4$D_{3/2}$ state for hyperfine-structure determination

We report a measurement of the hyperfine-structure constants of the $^{85}$Rb 4$D_{3/2}$ state using a two-photon 5$S_{1/2}\rightarrow$4$D_{3/2}$ transition. The hyperfine transitions are probed by measuring the transmission of the low-power 795-nm lower-stage laser beam through a cold-atom sample as a function of 795-nm laser frequency, with the frequency of the upper-stage 1476-nm laser fixed. All 4 hyperfine components are well-resolved in the recorded transmission spectra. AC shifts are carefully considered. The field-free hyperfine line positions are obtained by extrapolating measured line positions to zero laser power. The magnetic-dipole and electric-quadrupole constants, $A$ and $B$, are determined from the hyperfine intervals to be 7.419(35)~MHz and 4.19(19)~MHz, respectively. The results are evaluated in context with previous works. Possible uses of the Rb 4$D_J$ states in Rydberg-atom-physics, precision-metrology and quantum-technology applications are discussed.

physics.atom-ph↗

arXiv2023

Electric field analysis in a cold-ion source using Stark spectroscopy of Rydberg atoms

We analyze electric fields in ion sources generated by quasi-continuous photo-ionization of cold Rb atoms trapped in the focal spot of a near-concentric, in-vacuum cavity for 1064-nm laser light. Ion streams are extracted with an external electric field, ${\bf{F}}$. Stark effects of Rb 57$F$ and of nearby high-angular-momentum Rydberg levels, which exhibit large, linear Stark shifts, are employed to study the net electric-field probability distribution within the ion-source region over an extraction-field range of $0<F<0.35$ V/cm. For $F=0$, we also investigate ion-field-induced Stark spectra of the 60$P_{1/2}$-state, which exhibits a (lesser) quadratic electric-field response that affords a simplified electric-field analysis. Experimental Rydberg spectra are compared with theoretical Stark spectra, which are weighed with net electric-field distributions obtained from classical ion-trajectory simulations that include Coulomb interactions. Experiments and models agree well. At small $F$ and high ion source rates, the field approximately follows a Holtsmark distribution, and the ion streams are degraded by the Coulomb micro-fields. With increasing $F$ and at lower ion source rates, the fields become narrowly distributed around ${\bf{F}}$, resulting in directional ion streams that are less degraded by micro-fields. Our results are of interest for monitoring cold-ion sources for focused-ion-beam applications, where Coulomb interactions are of concern, and for studies of electric fields in cold plasmas.

physics.atom-ph↗

arXiv2022

Dynamic polarizability of the $^{85}$Rb $5D_{3/2}$-state in 1064 nm light

We report a measurement of the dynamic (ac) scalar polarizability of the $5D_{3/2}$ state in $^{85}$Rb atoms at a laser wavelength of 1064~nm. Contrary to a recent measurement in Phys. Rev. \textbf{A} 104, 063304 (2021), the experiments are performed in a low-intensity regime in which the ac shift is less than the $5D_{3/2}$ state's hyperfine structure, as utilized in numerous experiments with cold, trapped atoms. The extracted ac polarizability is $α_{5D_{3/2}} = -499\pm59$~a.u., within the uncertainty of the aforementioned previous result. The calibration of the 1064~nm light intensity, performed by analyzing light shifts of the D1 line, is the main source of uncertainty. Our results are useful for applications of the Rb $5D_{3/2}$ state in metrology, quantum sensing, and fundamental-physics research on Rydberg atoms and molecules.

physics.atom-ph↗

arXiv2022

Principles of tractor atom interferometry

We present possible design concepts for a tractor atom interferometer (TAI) based on three-dimensional confinement and transport of ultracold atoms. The confinement reduces device size and wave-packet dispersion, enables arbitrary holding times, and facilitates control to create complex trajectories that allow for optimization to cancel unwanted sensitivity, fast splitting and recombination, and suppression of detrimental nonadiabatic excitation. Thus, the design allows for further advancement of compact, high-sensitivity, quantum sensing technology. In particular, we focus on the implementation of quantum-enhanced accelerometers and gyroscopes. We discuss TAI protocols for both spin-dependent and scalar trapping potentials. Using optimal control theory, we demonstrate the splitting of the wave function on a time scale two orders of magnitude shorter than the previous proposal using adiabatic dynamics, thus maximizing the time spent at full separation, where the interferometric phase is accumulated. Lastly, we explore the possibility of including non-classical correlations between the atoms to improve sensitivity. The performance estimates for TAI give a promising perspective for atom-interferometry-based sensing, significantly exceeding the sensitivities of current state-of-the-art devices.

physics.atom-ph↗

arXiv2022

Nonadiabatic decay of metastable states on coupled linear potentials

Avoided crossings of level pairs with opposite slopes can form potential energy curves for the external degree of freedom of quantum particles. We investigate nonadiabatic decay of metastable states on such avoided crossings (MSACs) using diabatic and adiabatic representations. The system is described by a single scaled adiabaticity parameter, $V$. The time-independent two-component Schrödinger equation is solved in both representations, and the nonadiabatic lifetimes of MSACs are determined from a wave-function flux calculation and from the Breit-Wigner formula, leading to four lifetime values for each MSAC. We also solve the time-dependent Schrödinger equation in both pictures and derive the MSAC lifetimes from wave-function decay. The sets of six non-perturbative values for the MSAC lifetimes agree well, validating the approaches. As the adiabaticity parameter $V$ is increased by about a factor of ten, the MSAC character transitions from marginally to highly stable, with the lifetimes increasing by about ten orders of magnitude. The $ν$-dependence of the lifetimes in several regimes is discussed. Time-dependent perturbation theory is found to yield approximate lifetimes that deviate by $\lesssim 30\%$ from the non-perturbative results, while predictions based on the semi-classical Landau-Zener tunneling equation are found to be up to a factor of twenty off, over the ranges of $V$ and $ν$ studied. The results are relevant to numerous atomic and molecular systems with quantum states on intersecting, coupled potential energy curves.

quant-ph↗

arXiv2021

Gauge effects in bound-bound Rydberg-transition matrix elements

Accurate data on electric-dipole transition matrix elements (EDTMs) for bound-bound Rydberg-atom transitions become increasingly important in science and technology. Here we compute radial EDTMs of rubidium using the length, velocity and acceleration gauges for electric-dipole-allowed transitions between states with principal and angular-momentum quantum numbers ranging from 15 to 100. Wave-functions are computed based upon model potentials from Marinescu et al., Phys. Rev. A {\bf{49}}, 982 (1994). Length-gauge EDTMs, often used for low-$\ell$ transitions, are found to deviate from the fundamentally more accurate velocity-gauge EDTMs by relative amounts of up to $\sim 10^{-3}$. We discuss the physical reasons for the observed gauge differences, explain the conditions for applicability of the velocity and length gauges for different transition series, and present a decision tree of how to choose EDTMs. Implications for contemporary Rydberg-atom applications are discussed.

physics.atom-ph↗

arXiv2021

Non-adiabatic decay of Rydberg-atom-ion molecules

The decay of Rydberg-atom-ion molecules (RAIMs) due to non-adiabatic couplings between electronic potential energy surfaces is investigated. We employ the Born-Huang representation and perform numerical simulations using a Crank-Nicolson algorithm. The non-adiabatic lifetimes of rubidium RAIMs for the lowest ten vibrational states, $ν$, are computed for selected Rydberg principal quantum numbers, $n$. The non-adiabatic lifetimes are found to generally exceed the radiative Rydberg-atom lifetimes. We observe and explain a trend of the lifetimes as a function of $ν$ and $n$, and attribute irregularities to quantum interference arising from a shallow potential well in an inner potential surface. Our results will be useful for future spectroscopic studies of RAIMs.

physics.atom-ph↗

arXiv2021

AC polarizability and photoionization cross-section measurements in an optical lattice

We use double-resonant two-photon laser spectroscopy to measure the dynamic scalar polarizability of the rubidium 5$D_{3/2}$ level, $α^{S}_{5D_{3/2}}$, at a wavelength of $λ=1064$~nm. Since $λ$ is shorter than the photoionization (PI) limit of the Rb 5$D_{3/2}$ level, $α^{S}_{5D_{3/2}}$ depends on both bound-bound and bound-free transition matrix elements. The level also undergoes significant broadening due to PI. The $1064$-nm field is applied in the form of a deep optical lattice ($\sim10^{5}$~photon recoils) generated by an in-vacuum field-enhancement cavity. In our spectroscopic method, we use known dynamic polarizabilities to eliminate the need to measure the light intensity. Our method yields, in atomic units, $α^{S}_{5D_{3/2}}=-524(17)$, in agreement with estimates. Additionally, we extract the $5D_{3/2}$ photoionization cross section $σ$ at $1064$~nm from spectral linewidths; we find $σ=44(1)$~Mb.

physics.atom-ph↗