Crystals of metallic rubidium are observed ``growing'' from paraffin coating of buffer-gas-free glass vapor cells. The crystals have uniform square cross-section, $\approx 30 μ$m on the side, and reach several mm in length.
We present the results of a study on relaxation and diffusion processes of rubidium atoms in a rubidium cell with an internal vapor source. The cell is an evacuated glass bulb, which is characterized in that the source of atomic vapors in the form of a metal film Rb is evenly distributed throughout the inner surface of the bulb, and the paraffin film is uniformly distributed over the entire area and over the metal surface. By using laser optical pumping, we performed measurements of the relaxation time and the average number of bounces of optical pumped rubidium atoms in the bulb. We have meas…
The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D2 transitions in atomic rubidium is described. A 5 cm-long vapor cell is placed in a double-solenoid arrangement to produce the required magnetic field; the heat from the solenoid is used to increase the vapor pressure and correspondingly the DAVLL signal. We have characterized experimentally the dependence of important features of the DAVLL signal on magnetic field and cell temperature. For the weaker transitions both the amplitude and gradient of the signal are inc…
We propose a new scheme for interrogating a warm rubidium vapor using two different clock lasers. Performance-wise, this approach is distinctly different from the recently proposed two-color two-photon rubidium clocks as our scheme does not trade off the AC Stark suppression against an increased sensitivity to the cell-temperature/pressure. Instead, our approach compensates all, the AC-Stark shift and the temperature & pressure-induced frequency shifts. The proposed scheme also makes use of the modulation transfer technique, which enables a two-orders of magnitude increase in the signal-to-noi…
We report on the experimental demonstration of light dragging effect due to atomic motion in a rubidium vapor cell. We found that the minimum group velocity is achieved for light red-shifted from the center of the atomic resonance, and that the value of this shift increases with decreasing group velocity, in agreement with the theoretical predictions by Kocharovskaya, Rostovtsev, and Scully [Phys. Rev. Lett. {\bf 86}, 628 (2001)].
Resonances in the magnetic decoupling curves for the spin relaxation of dense alkali-metal vapors prove that much of the relaxation is due to the spin-axis interaction in triplet dimers. Initial estimates of the spin-axis coupling coefficients for the dimers are 290 MHz for Rb; 2500 MHz for Cs.
Using the z-scan technique, we have measured the self-induced absorptive and refractive nonlinear behavior of hot atomic rubidium vapor within the Doppler profile of the D2 line. We observe large nonlinear amplitude and phase effects with only tens of microwatts of incident power. Our results are in good agreement with numerical calculations based on an analytic model of a Doppler- broadened two-level system.
We report on the first observation of electromagnetically induced transparency (EIT) in a ladder system in the presence of a buffer gas. In particular we study the 5S1/2 - 5P3/2 - 5D5/2 transition in thermal rubidium vapor with a neon buffer gas at a pressure of 6 Torr. In contrast to the line narrowing effect of buffer gas on Λ-systems we show that the presence of the buffer gas leads to an additional broadening of (32 +/- 5) MHz, which suggests a cross section for Rb(5D5/2)-Ne of σ = (7 +/- 1) x 10-19 m2. However, in the limit where the coupling Rabi frequency is larger than k the collisiona…
Transmission of light through an atomic sample placed between crossed polarizers in a magnetic field is jointly determined by Faraday rotation and net absorption: transmission increases with rotation and decreases with absorption. Both rotation and absorption are proportional to the atomic density N0, hence, in a certain range of N0, the two effects may compete yielding a distinct density dependence of the transmitted light. We have studied such dependence in rubidium vapor for N0 = 7.5*10^9 to 7.5*10^11 at/cm^3 with resonant laser light. We present interpretation of the competition effect and…
We experimentally investigated Rabi resonance-based continuously frequency-tunable microwave (MW) magnetic field detection using a single hybrid vapor cell filled with cesium and rubidium atoms. The multispecies atomic systems, with their tunable abilities in transition frequencies, enabled this atomic sensing head to cover a broader detectable MW field scope compared to the use of a single metal atom. Here, we demonstrated the simultaneous observation of atomic Rabi resonance signals with 85Rb, 87Rb, and 133Cs in the same vapor cell. Using an experimentally feasible static magnetic field (DC …
It is clearly important to pursue atomic standards for quantities like electromagnetic fields, time, length and gravity. We have recently shown, using Rydberg states, that Rb atoms in a vapor cell can serve as a practical, compact standard for microwave electric field strength. Here, we demonstrate, for the first time, that Rb atoms excited in a vapor cell can also be used for vector microwave electrometry by using Rydberg atom electromagnetically induced transparency. We describe the measurements necessary to obtain an arbitrary microwave electric field polarization at a resolution of $0.5^\c…
We have studied modification of the fluorescence spectra of a room-temperature atomic rubidium vapor in the region of $^{85}$Rb and $^{87}$Rb D$_2$ line while changing the temporal rate of linear (triangular) scanning of laser radiation frequency. Increase of the ramping speed over certain value ($\approx$ 10$^6$ MHz/s) results in essential modification of magnitudes of individual atomic transitions, different on rising and falling slopes, which characterize transition from a steady-state interaction regime to a transient one. Our experimental results are well consistent with the developed the…
We have studied the resonance fluorescence of a room-temperature rubidium vapor exited to the atomic 5P3/2 state (D2 line) by powerful single-frequency cw laser radiation (1.25 W/cm^2) in the presence of a magnetic field. In these studies, the slow, linear scanning of the laser frequency across the hyperfine transitions of the D2 line is combined with a fast linear scanning of the applied magnetic field, which allows us to record frequency-dependent Hanle resonances from all the groups of hyperfine transitions including V- and Lambda - type systems. Rate equations were used to simulate fluores…
We present experimental and numerical studies of nonlinear magneto-optical rotation (NMOR) in rubidium vapor excited with resonant light tuned to the $5^2\!S_{1/2}\rightarrow 6^2\!P_{1/2}$ absorption line (421~nm). Contrary to the experiments performed to date on the strong $D_1$ or $D_2$ lines, in this case, the spontaneous decay of the excited state $6^2\!P_{1/2}$ may occur via multiple intermediate states, affecting the dynamics, magnitude and other characteristics of NMOR. Comparing the experimental results with the results of modelling based on Auzinsh et al., Phys. Rev. A 80, 1 (2009), w…
Electromagnetically induced transparency (EIT) on atomic D$_{1}$ line of rubidium is studied using a nanometric-thin cell with atomic vapor column length in the range of L= 400 - 800 nm. It is shown that the reduction of the cell thickness by 4 orders as compared with an ordinary cm-size cell still allows to form an EIT resonance for $L= λ$ ($λ=794$ nm) with the contrast of up to 40%. Remarkable distinctions of EIT formation in nanometric-thin and ordinary cells are demonstrated. Despite the Dicke effect of strong spectral narrowing and increase of the absorption for $L=$ $λ/2$, EIT resonance …
Diffusion is the main limitation of storage time in spatially multimode applications of warm atomic vapors. Precise knowledge of diffusional decoherence in the system is desired for designing most of vapor memory setups. Here we present a novel, efficient and direct method of measuring unbiased diffusional decoherence, clearly distinguished from all other decoherence sources. We found the normalized diffusion coefficients of rubidium atoms in noble gases to be as follows: neon 0.20 cm$^{2}$/s, krypton 0.068 cm$^{2}$/s and we are the first to give an experimental result for rubidium in xenon: 0…
We investigate the transient response of the generated light from Four-Wave Mixing (FWM) in the diamond configuration using a step-down field excitation. The transients show fast decay times and oscillations that depend on the detunings and intensities of the fields. A simplified model taking into account the thermal motion of the atoms, propagation, absorption and dispersion effects shows qualitative agreement with the experimental observations with the energy levels in rubidium (5S1/2, 5P1/2, 5P3/2 and 6S1/2). The atomic polarization comes from all the contributions of different velocity cla…
Compactness, robustness and autonomy of optical frequency references are prerequisites for reliable operation in mobile systems, on ground as well as in space. We present a standalone plug and play optical frequency reference device based on frequency modulation spectroscopy of the D2-transition in rubidium at 780 nm. After a single button press the hand-sized laser module, based on the micro-integrated laser-optical bench described in [J. Opt. Soc. Am. B 38, 1885-1891 (2021)], works fully autonomous and generates 6 mW of frequency stabilized light with a relative frequency instability of 1.4e…
We present a new technique to measure pulsed magnetic fields based on the use of Rubidium in gas phase as a metrological standard. We have therefore developed an instrument based on laser inducing transitions at about 780~nm (D2 line) in a Rubidium gas contained in a mini-cell of 3~mm~x~3~mm cross section. To be able to insert such a cell in a standard high field pulsed magnet we have realized a fibred probe kept at a fixed temperature. Transition frequencies for both the $π$ (light polarization parallel to the magnetic field) and $σ$ (light polarization perpendicular to the magnetic field) co…
We report on the observation of a Zeeman shift (order of 100 MHz) of the Doppler-broadened D2 transition of both 85Rb and 87Rb isotopes via transmission through a tapered optical nanofiber in the presence of a DC magnetic field. Linearly-polarized light propagating in the nanofiber is analyzed as a superposition of two orthogonally circularly-polarized orientations, σ+ and σ-. In the absence of the magnetic field, the absorption of these polarizations by the atomic vapor, via the evanescent field at the waist of the nanofiber, is degenerate. When a weak magnetic field is applied parallel to th…
We report on experimental and theoretical investigations of the polarization dependence of magnetic resonance generated by synchronous optical pumping. Magnetic resonances with narrow linewidth are generated experimentally using a rubidium vapor cell with octade-cyltrichlorosilane (OTS) antirelaxation coating on inner walls. We studied the effect of light ellipticity on the amplitudes and widths of magnetic resonances by matching the light modulation frequency with 2 Ω_L (alignment) and Ω_L(orientation) in a Bell-Bloom interaction geometry, where Ω_L corresponds to the Larmor frequency. Both 2…
Spatio-spectral vector light created by optical activity in rubidium vapor
University of Glasgow(格拉斯哥大学);Fraunhofer UK Research Ltd.(弗劳恩霍夫英国研究有限公司);Physikalisch-Technische Bundesanstalt(德国联邦物理技术研究院);Technische Universität Braunschweig(布伦瑞克工业大学)
Optical two-dimensional coherent spectroscopy (2DCS) has become a powerful tool for studying energy level structure, dynamics, and coupling in many systems including atomic ensembles. Various types of two-dimensional (2D) spectra, including the so-called single-quantum, zero-quantum, and double-quantum 2D spectra, of both D lines (D$_1$ and D$_2$ transitions) of potassium (K) atoms have been reported previously. For rubidium (Rb), a major difference is that the D-lines are about 15 nm apart as opposed to only about 3 nm for K. Simultaneously exciting both D-lines of Rb atoms requires a broader…
We experimentally investigate the optical storage of perfect optical vortex (POV) and spatially multimode perfect optical vortex (MPOV) beams via electromagnetically induced transparency (EIT) in a hot vapor cell. In particular, we study the role that phase gradients and phase singularities play in reducing the blurring of the retrieved images due to atomic diffusion. Three kinds of manifestations are enumerated to demonstrate such effect. Firstly, the suppression of the ring width broadening is more prominent for POVs with larger orbital angular momentum (OAM). Secondly, the retrieved double-…
We experimentally demonstrate a one-color two-photon transition from the $5\mathit{S}_{1/2}$ ground state to the $6\mathit{S}_{1/2}$ excited state in rubidium (Rb) vapor using a continuous wave laser at 993 nm. The Rb vapor contains both isotopes ($^{85}$Rb and $^{87}$Rb) in their natural abundances. The electric dipole allowed transitions are characterized by varying the power and polarization of the excitation laser. Since the optical setup is relatively simple, and the energies of the allowed levels are impervious to stray magnetic fields, this is an attractive choice for a frequency refere…
Atomic vapor of four different paramagnetic species: gold, silver, lithium, and rubidium, is produced and studied inside several buffer gases: helium, nitrogen, neon, and argon. The paramagnetic atoms are injected into the buffer gas using laser ablation. Wires with diameters 25 $μ$m, 50 $μ$m, and 100 $μ$m are used as ablation targets for gold and silver, bulk targets are used for lithium and rubidium. The buffer gas cools and confines the ablated atoms, slowing down their transport to the cell walls. Buffer gas temperatures between 20 K and 295 K, and densities between $10^{16}$ cm$^{-3}$ and…
Antirelaxation surface coatings allow long spin relaxation times in alkali-metal cells without buffer gas, enabling faster diffusion of the alkali atoms throughout the cell and giving larger signals due to narrower optical linewidths. Effective coatings were previously unavailable for operation at temperatures above 80 C. We demonstrate that octadecyltrichlorosilane (OTS) can allow potassium or rubidium atoms to experience hundreds of collisions with the cell surface before depolarizing, and that an OTS coating remains effective up to about 170 C for both potassium and rubidium. We consider th…
Optical spectroscopy of atoms and molecules is a field where one usually operates very far from thermal equilibrium conditions. A prominent example is spectroscopy of thin vapors, where the pump irradiation leads to a non equilibrium distribution within the electronic structure that is well shielded from the environment. Here we describe experimental work investigating absorption and emission lines of rubidium vapor subject to a noble buffer gas environment with pressure 100 to 200 bar, a regime interpolating between usual gas phase and liquid solid state conditions. Frequent elastic collision…
Measurements were made to determine the density of rubidium dimer vapor in paraffin-coated cells. The number density of dimers and atoms in similar paraffin-coated and uncoated cells was measured by optical spectroscopy. Due to the relatively low melting point of paraffin, a limited temperature range of 43-80 deg C was explored, with the lower end corresponding to a dimer density of less than 10^7 cm^(-3). With one-minute integration time, a sensitivity to dimer number density of better than 10^6 cm^(-3) was achieved. No significant difference in dimer density was observed between the cells.
We present evidence for Rydberg-Rydberg interaction in a gas of rubidium atoms above room temperature. Rabi oscillations on the nanosecond timescale to different Rydberg states are investigated in a vapor cell experiment. Analyzing the atomic time evolution and comparing to a dephasing model we find a scaling with the Rydberg quantum number n that is consistent with van der Waals interaction. Our results show that the interaction strength can be larger than the kinetic energy scale (Doppler width) which is the requirement for realization of thermal quantum devices in the GHz regime.
We have developed a versatile pulsed laser system for high precision magnetometry. The operating wavelength of the system can be configured to optically pump alkali vapors such as rubidium and cesium. The laser system consists of an auto-locked, interference filter stabilized, external cavity diode laser (ECDL), a tapered waveguide amplifier, and a pulsing module. The auto-locking controller can be used by an untrained operator to stabilize the laser frequency with respect to a library of atomic, molecular, and solid-state spectral markers. The ECDL output can be amplified from 20 mW to 2 W in…
We demonstrate continuous-frequency electric field measurements of high-intensity microwaves via optical spectroscopy in a small atomic vapor cell. The spectroscopic response of a room-temperature rubidium atomic vapor in a glass cell is investigated and employed for absolute measurements of K$_a$-band microwave electric fields from $\sim$200 V/m to $>$1 kV/m over a continuous frequency range of $\pm $1 GHz (15% band coverage). It is established that in strong microwave fields frequency-specific spectral features allow for electric field measurements over a large continuous frequency range.
We present a very sensitive and scalable method to measure the population of highly excited Rydberg states in a thermal vapor cell of rubidium atoms. We detect the Rydberg ionization current in a 5 mm electrically contacted cell. The measured current is found to be in excellent agreement with a theory for the Rydberg population based on a master equation for the three level problem including an ionization channel and the full Doppler distributions at the corresponding temperatures. The signal-to-noise ratio of the current detection is substantially better than purely optical techniques.
We report on the observation of Rabi oscillations to a Rydberg state on a timescale below one nanosecond in thermal rubidium vapor. We use a bandwidth-limited pulsed excitation and observe up to 6 full Rabi cycles within a pulse duration of ~ 4 ns. We find good agreement between the experiment and numerical simulations based on a surprisingly simple model. This result shows that fully coherent dynamics with Rydberg states can be achieved even in thermal atomic vapor thus suggesting small vapor cells as a platform for room temperature quantum devices. Furthermore the result implies that previou…
We report on rubidium vapor-cell Rydberg electromagnetically induced transparency (EIT) in a 0.7~T magnetic field where all involved levels are in the hyperfine Paschen-Back regime, and the Rydberg state exhibits a strong diamagnetic interaction with the magnetic field. Signals from both $^{85}\mathrm{Rb}$ and $^{87}\mathrm{Rb}$ are present in the EIT spectra. This feature of isotope-mixed Rb cells allows us to measure the field strength to within a $\pm 0.12$\% relative uncertainty. The measured spectra are in excellent agreement with the results of a Monte Carlo calculation and indicate unex…
We report the fabrication of alkali-metal vapor cells using femtosecond laser machining. This laser-written vapor-cell (LWVC) technology allows arbitrarily-shaped 3D interior volumes and has potential for integration with photonic structures and optical components. We use non-evaporable getters both to dispense rubidium and to absorb buffer gas. This enables us to produce cells with sub-atmospheric buffer gas pressures without vacuum apparatus. We demonstrate sub-Doppler saturated absorption spectroscopy and single beam optical magnetometry with a single LWVC. The LWVC technology may find appl…
We measure strong radio-frequency (RF) electric fields using rubidium Rydberg atoms prepared in a room-temperature vapor cell as field sensors. Electromagnetically induced transparency is employed as an optical readout. We RF-modulate the 60$S_{1/2}$ and 58$D_{5/2}$ Rydberg states with 50~MHz and 100~MHz fields, respectively. For weak to moderate RF fields, the Rydberg levels become Stark-shifted, and sidebands appear at even multiples of the driving frequency. In high fields, the adjacent hydrogenic manifold begins to intersect the shifted levels, providing rich spectroscopic structure suitab…
Alkali vapors, and in particular rubidium, are being used extensively in several important fields of research such as slow and stored light non-linear optics3 and quantum computation. Additionally, the technology of alkali vapors plays a major role in realizing myriad industrial applications including for example atomic clocks magentometers8 and optical frequency stabilization. Lately, there is a growing effort towards miniaturizing traditional centimeter-size alkali vapor cells. Owing to the significant reduction in device dimensions, light matter interactions are greatly enhanced, enabling n…
Atomic spin polarization of alkali atoms in the ground state can survive thousands of collisions with paraffin-coated cell walls. The resulting long spin-relaxation times achieved in evacuated, paraffin-coated cells enable precise measurement of atomic spin precession and energy shifts of ground-state Zeeman sublevels. In the present work, nonlinear magneto-optical rotation with frequency-modulated light (FM NMOR) is used to measure magnetic-field-induced spin precession for rubidium atoms contained in a paraffin-coated cell. The magnetometric sensitivity of FM NMOR for the rubidium D2 line is…
We present the results of a study of the diffusion of Rb atoms in paraffin - coated resonant vapor cells. We have modeled the Rb diffusion both in the cell and in the coating, assuming that the main loss of Rb atoms is due to the physical absorption of the atoms by the glass substrate. It is demonstrated that the equilibrium atomic density in the cell is a monotonic function of the thickness of the paraffin coating: the density increases with an increase in the thickness of the coating. The diffusion coefficient for rubidium in paraffin thin films has been determined to be equal to 4,7*10^-7 c…
Atomic-vapor density change due to light induced atomic desorption (LIAD) is studied in paraffin-coated rubidium, cesium, sodium and potassium cells. In the present experiment, low-intensity probe light is used to obtain an absorption spectrum and measure the vapor density, while light from an argon-ion laser, array of light emitting diodes, or discharge lamp is used for desorption. Potassium is found to exhibit significantly weaker LIAD from paraffin compared to Rb and Cs, and we were unable to observe LIAD with sodium. A simple LIAD model is applied to describe the observed vapor-density dyn…