Spectroscopy Of Rydberg Atoms Research Articles

Probing Polaron Clouds by Rydberg Atom Spectroscopy.

In recent years, Rydberg excitations in atomic quantum gases have become a successful platform to explore quantum impurity problems. A single impurity immersed in a Fermi gas leads to the formation of a polaron, a quasiparticle consisting of the impurity being dressed by the surrounding medium. With a radius of about the Fermi wavelength, the density profile of a polaron cannot be explored using insitu optical imaging techniques. In this Letter, we propose a new experimental measurement technique that enables the insitu imaging of the polaron cloud in ultracold quantum gases. The impurity atom induces the formation of a polaron cloud and is then excited to a Rydberg state. Because of the mesoscopic interaction range of Rydberg excitations, which can be tuned by the principal numbers of the Rydberg state, atoms extracted from the polaron cloud form dimers with the impurity. By performing first principle calculations of the absorption spectrum based on a functional determinant approach, we show how the occupation of the dimer state can be directly observed in spectroscopy experiments and can be mapped onto the density profile of the gas particles, hence providing a direct, real-time, and insitu measure of the polaron cloud.

Modulation spectroscopy of Rydberg atoms in an optical lattice

We develop and study quantum and semiclassical models of Rydberg-atom spectroscopy in amplitude-modulated optical lattices. Both initial- and target-state Rydberg atoms are trapped in the lattice. Unlike in other spectroscopic schemes, the modulation-induced ponderomotive coupling between the Rydberg states is spatially periodic and perfectly phase-locked to the lattice trapping potentials. This leads to a type of sub-Doppler mechanism which we explain in detail. In our exact quantum model, we solve the time-dependent Schr\"odinger equation in the product space of center-of-mass (COM) momentum states and the internal-state space. We also develop a perturbative model based on the band structure in the lattice and Fermi's golden rule, as well as a semiclassical trajectory model in which the COM is treated classically and the internal-state dynamics quantum-mechanically. In all models we obtain the spectrum of the target Rydberg-state population versus the lattice modulation frequency, averaged over the initial thermal COM momentum distribution of the atoms. We investigate the quantum-classical correspondence of the problem in several parameter regimes and exhibit spectral features that arise from vibrational COM coherences and rotary-echo effects. Applications in Rydberg-atom spectroscopy are discussed.

Spectroscopy of Rydberg Atoms in a Black-body Radiation field: Ionisation Rates and Effective Lifetimes

The combined relativistic energy approach and relativistic many-body perturbation theory, with a zeroth order approximation density functional theory, are used to calculate the ionisation rates and effective lifetimes values for Rydberg atoms in a black-body radiation field. Calculations for the rubidium atom in Rydberg states with principal quantum number n > 26 are presented and compared with available theoretical and experimental data.

Spectroscopy of cesium Rydberg atoms in strong radio-frequency fields

We study Rydberg atoms modulated by strong radio-frequency (RF) fields with a frequency of 70 MHz. The Rydberg atoms are prepared in a room temperature cesium cell, and their level structure is probed using electromagnetically induced transparency (EIT). As the RF field increases from the weak- into the strong-field regime, the range of observed RF-induced phenomena progresses from AC level shifts through increasingly pronounced and numerous RF-modulation sidebands to complex state-mixing and level-crossings with high-l hydrogen-like states. Weak anharmonic admixtures in the RF field generate clearly visible modifications in the Rydberg-EIT spectra. A Floquet analysis is employed to model the Rydberg spectra, and good agreement with the experimental observations is found. Our results show that all-optical spectroscopy of Rydberg atoms in vapor cells can serve as an antenna-free, atom-based and calibration-free technique to measure and map RF electric fields and to analyze their higher-harmonic contents.

Spectroscopy of Rydberg atoms in a Black-body radiation field: Relativistic theory of excitation and ionization

The combined relativistic energy approach and many-body perturbation theory with zeroth model potential approximation are used for computing Blackbody radiation ionization characteristics of the Rydberg atoms, in particular, the sodium in states with n=17,18,40-70. The calculated ionization rate values are compared with available theoretical and experimental data.

Frequency stabilization of multiple lasers and Rydberg atom spectroscopy

In this paper we report details of the apparatus and experimental techniques used to excite Rydberg states of 7Li using multiple diode lasers. Special attention is paid to frequency stabilization of the lasers and we show how three lasers can be stabilized using the fluorescence from a single atomic state. Laser spectroscopy of the 8p,9p, and 11p–15p states is then performed to determine the quantum defects of these states. Our measurement precision exceeds that of previous measurements of these defects by as much as a factor of 25. This work substantially extends our previous measurement of the 10p quantum defect, and we compare our measured defects with recent theoretical calculations for the np states across the range 8≤n≤15. The agreement with theory is excellent.

Coherent excitation of Rydberg atoms in micrometre-sized atomic vapour cells

The coherent control of mesoscopic ensembles of atoms and Rydberg atom blockade are the basis for proposed quantum devices such as integrable gates and single photon sources. So far, experimental progress has been limited to complex experimental setups that use ultracold atoms. Here, we show that coherence times of ~100ns are achievable with coherent Rydberg atom spectroscopy in um sized thermal vapor cells. We investigated states with principle quantum numbers between 30 and 50. Our results demonstrate that microcells with a size on the order of the blockade radius, ~2um, at temperatures of 100-300C are robust, promising candidates to investigate low dimensional strongly interacting Rydberg gases, construct quantum gates and build single photon sources.

High sensitivity spectroscopy of cesium Rydberg atoms using electromagnetically induced transparency

A high sensitivity spectroscopy of Rydberg atoms is presented by using electromagnetically induced transparency (EIT) in the 6S(1/2)-6P(3/2)-n D ladder-type system of cesium vapor cell at room temperature. The EIT spectra of 40 D Rydberg state are measured and the dependences of the EIT magnitude and linewidth on the coupling laser power are investigated in detail. The Rydberg EIT linewidth is measured to be about 5.6 MHz when the powers of probe and coupling lasers are 50 microW and 5.2 mW, respectively, and which is close to the natural linewidth of cesium atoms. The effect of double resonance optical pumping on EIT is also investigated. The fine structures of nD (n = 39-55) are measured and the experimental result is in agreement with quantum defect theory.

Laser Optogalvanic Spectroscopy: Experimental Details and Potential Applications in R and D

Laser Optogalvanic Spectroscopy (LOGS) is an extremely sensitive detection technique based on the 'Optogalvanic Effect'. The impedance change of gaseous discharge following the absorption of resonant laser light by the discharge species has proved to be a powerful spectroscopic tool to investigate all kinds of matter in vapour phase in discharge plasmas and flames. LOGS does not require any optical detector and the signal-to-noise ratios are often greater than 10/sup 3/. The advent of tunable lasers has pushed LOGS as a unique detection technique, efficient over a wide frequency spectrum from UV through visible to IR. As a simple and most sensitive detection technique, LOGS can have diverse practical applications in science and technology. The experimental details with different discharge excitations and the potential applications of LOGS are briefly described. Some prominent practical applications like wavelength calibration, laser linewidth determination, trace element detection, isotope analysis, material characterisation, laser frequency and power stabilisation, Rydberg atom spectroscopy and combustion and plasma diagnostics are briefly discussed.

High resolution laser spectroscopy of Ba Rydberg atoms

The purpose of the present paper is to illustrate some selected aspects of high resolution laser spectroscopy of Rydberg atoms, rather than giving an extensive review of the state of the art. The following topics will be discussed: (i) Excitation and detection of Ba Rydberg atoms with principal quantum numbers up ton≲300; (ii) Stark effect and atomic diamagnetism of high-n Ba Rydberg states in thel-mixing region, (iii) Resonance in singlet-triplet mixing of 6snp1P1 and 6snd1D2 Ba Rydberg states deduced from hyperfine structure measurements.

Spin waves and quantum collective phenomena in Boltzmann gases

The concept of the quantum gas is introduced and illustrated by numerous examples. The fundamentals of the theory of collective phenomena in quantum Maxwellian gases are surveyed in a simple and readily assimilated form, and possible experimental studies are outlined. Particular attention is devoted to weakly-damped spin waves. The spectrum of these waves is calculated and the magnetic susceptibility generalized. The results obtained are compared with experimental data on spin waves in gaseous H,3He,and 3He–4He quantum solutions. It is shown that, at low temperatures, spin-polarized Boltzmann gases exhibit longrange spin correlations which fall off as r-1 at large distances. The equations of spin dynamics are solved for arbitrary temperatures and degrees of polarization, both in the weakly damped and diffusion regimes. The thermodynamics of spin-polarized gases and some of the features of transport phenomena are examined. Paramagnetic resonance and other collective effects in binary quantum gases are discussed. Magnetic and structural thermodynamic phase transitions in binary Maxwellian gases are predicted. Collective phenomena in semimagnetic semiconductors and analogous effects in the spectroscopy of Rydberg atoms and levitating electrons are discussed.

Effect of blackbody radiation on the hydrogen spectrum

The partition function of a single hydrogen atom diverges. While the astrophysical solution to this dilemma is the introduction of a density dependent alteration of the partition function, the question of what happens in an arbitrarily rarefied gas remains open. It is argued that in this case blackbody radiation changes the atom’s spectrum. A unified derivation including these effects and the nonrelativistic Lamb shift and spontaneous emission is presented. Then recent numerical calculations performed by workers in the field of Rydberg atom spectroscopy are utilized to estimate the principal quantum number for which blackbody radiation significantly alters the spectrum.