Atomic Vapor Research Articles

Comparison and analysis of methods for measuring the spin transverse relaxation time of rubidium atomic vapor

Comparison and analysis of methods for measuring the spin transverse relaxation time of rubidium atomic vapor

Broad Instantaneous Bandwidth Microwave Spectrum Analyzer with a Microfabricated Atomic Vapor Cell

We report on broad instantaneous bandwidth microwave spectrum analysis with hot Rb87 atoms in a microfabricated vapor cell in a large magnetic field gradient. The sensor is a MEMS atomic vapor cell filled with isotopically pure Rb87 and N2 buffer gas to localize the motion of the atoms. The microwave signals of interest are coupled through a coplanar waveguide to the cell, inducing spin-flip transitions between optically pumped ground states of the atoms. A static magnetic field with large gradient maps the frequency spectrum of the input microwave signals to a position-dependent spin-flip pattern on absorption images of the cell recorded with a laser beam onto a camera. In our proof-of-principle experiment, we demonstrate a microwave spectrum analyzer that has ≈1 GHz instantaneous bandwidth centered around 13 GHz, 3 MHz frequency resolution, 2 kHz refresh rate, and a −23 dBm single-tone microwave power detection limit in 1 s measurement time. A theoretical model is constructed to simulate the image signals by considering the processes of optical pumping, microwave interaction, diffusion of Rb87 atoms, and laser absorption. We expect to reach more than 25 GHz instantaneous bandwidth in an optimized setup, limited by the applied magnetic field gradient. Our demonstration offers a practical alternative to conventional microwave spectrum analyzers based on electronic heterodyne detection. Published by the American Physical Society 2024

Room temperature single-photon terahertz detection with thermal Rydberg atoms

Single-photon terahertz (THz) detection is one of the most demanding technologies for a variety of fields and could lead to many breakthroughs. Although significant progress has been made in the past two decades, operating it at room temperature still remains a great challenge. Here, we demonstrate, for the first time, a room temperature THz detector at single-photon levels based on nonlinear wave mixing in thermal Rydberg atomic vapor. The low-energy THz photons are coherently upconverted to high-energy optical photons via a nondegenerate Rydberg state involved in a six-wave mixing process, and therefore, single-photon THz detection is achieved by a conventional optical single-photon counting module. The noise equivalent power of such a detector reaches 9.5 × 10−19 W/Hz1/2, which is more than four orders of magnitude lower than the state-of-the-art room temperature THz detectors. The optimum quantum efficiency of the whole-wave mixing process is about 4.3%, with 40.6 dB dynamic range, and the maximum conversion bandwidth is 172 MHz, which is all-optically controllable. The developed fast and continuous-wave single-photon THz detector at room temperature operation has a great potential for portability and chip-scale integration, and could be revolutionary for a wide range of applications in remote sensing, wireless communication, biomedical diagnostics, and quantum optics.

Observation of microwave enhancement effect based on Rydberg atomic vapor cell

Observation of microwave enhancement effect based on Rydberg atomic vapor cell

Continuous broadband Rydberg receiver using AC Stark shifts and Floquet states

We demonstrate the continuous broadband microwave receivers based on AC Stark shifts and Floquet states of Rydberg levels in a cesium atomic vapor cell. The resonant transition frequency of two adjacent Rydberg states 78 S1/2 and 78 P1/2 is tuned based on AC Stark effect of 70 MHz radio frequency (RF) field that is applied outside the vapor cell. The use of the j=1/2 Rydberg states ensures that only a single mj sublevel is involved. The generated Rydberg Floquet states act to enhance the sensitivity of the AC-Stark-tuned states when the frequency is matched and further extend the bandwidths. We achieve microwave field measurements with over 1.172 GHz continuous frequency tuning and a sensitivity ranging from 280.2 nVcm−1Hz−1/2 to 14.6 μ Vcm−1Hz−1/2. The achieving of continuous frequency and high sensitivity microwave detection will promote the application of Rydberg receivers in the radar technique and wireless communication.

Rydberg electromagnetically induced transparency based laser lock to Zeeman sublevels with 0.6GHz scanning range.

We propose a technique for frequency locking a laser to the Zeeman sublevel transitions between the 5P3/2 intermediate and 32D5/2 Rydberg states in 87Rb. This method allows for continuous frequency tuning over 0.6GHz by varying an applied external magnetic field. In the presence of the applied field, the electromagnetically induced transparency (EIT) spectrum of an atomic vapor splits via the Zeeman effect according to the strength of the magnetic field and the polarization of the pump and probe lasers. We show that the 480nm pump laser, responsible for transitions between the Zeeman sublevels of the intermediate state and the Rydberg state, can be locked to the Zeeman-split EIT peaks. The short-term frequency stability of the laser lock is 0.15MHz, and the long-term stability is within 0.5MHz. The linewidth of the laser lock is ∼0.8 and ∼1.8MHz in the presence and absence of the external magnetic field, respectively. In addition, we show that in the absence of an applied magnetic field and adequate shielding, the frequency shift of the lock point has a peak-to-peak variation of 1.6MHz depending on the polarization of the pump field, while when locked to Zeeman sublevels, this variation is reduced to 0.6MHz. The proposed technique is useful for research involving Rydberg atoms, where large continuous tuning of the laser frequency with stable locking is required.

Graphene reinforced magnesium metal matrix composites by infiltrating coated-graphene preform with melt

Graphene’s exceptional mechanical, electrical, and thermal conductivity capabilities make it an ideal reinforcement for metal matrix composites. However, graphene is hard to be dispersed in the melt metal due to its high surface energy, non-wetting nature, and strong van der Waals interactions between graphene sheets, which weaken the reinforcing efficiency of composites. A novel process by infiltrating the coated-graphene preform with melt magnesium was proposed to improve the dispersion of graphene in the magnesium matrix. Graphene preforms with oriented pores were prepared by a directional freeze-drying method. Magnesium oxide coatings were deposited on the surface of graphene inside the graphene preform using the evaporation of magnesium atoms to enhance the strength as well as the wettability between the preform and magnesium matrix. Magnesium matrix composites were fabricated by liquid-solid pressure infiltrating coated-graphene preform with molten magnesium. The microstructure of graphene preforms and composites and mechanical properties of the composites were characterized. The results show that graphene is uniformly dispersed in the matrix and presents a reticular structure, and the hardness, elastic modulus, and compressive strength of the composite were improved apparently compared to the matrix. This study suggests that the method of preparing composites by infiltration provides a novel strategy for fabricating nano-material reinforced magnesium matrix composites.

Additive manufacturing of functionalised atomic vapour cells for next-generation quantum technologies

Abstract Atomic vapour cells are an indispensable tool for quantum technologies (QT), but potential improvements are limited by the capacities of conventional manufacturing techniques. Using an additive manufacturing (AM) technique – vat polymerisation by digital light processing - we demonstrate, for the first time, a 3D-printed glass vapour cell. The exploitation of AM capacities allows intricate internal architectures, overprinting of 2D optoelectronical materials to create integrated sensors and surface functionalisation, while also showing the ability to tailor the optical properties of the AM glass by in-situ growth of gold nanoparticles. The produced cells achieve ultra-high vacuum of 2 x 10-9 mbar and enable Doppler-free spectroscopy; we demonstrate laser frequency stabilisation as a QT application. These results highlight the transformative role that AM can play for QT in enabling compact, optimised and integrated multi-material components and devices.

Publisher Correction: Rydberg states of alkali atoms in atomic vapour as SI-traceable field probes and communications receivers

Publisher Correction: Rydberg states of alkali atoms in atomic vapour as SI-traceable field probes and communications receivers

Phase-modulation-induced reconfigurable rotating photonic lattices in atomic vapors.

We propose a method to prepare optically induced rotating hexagonal and honey-comb photonic lattices by employing the phase modulated three-beam interference in atomic vapors with electromagnetically induced transparency. The phase differences among the three beams are dynamically elaborated to synthesize the circular motion (in transverse dimensions) of waveguides in the photonic lattices. Further, we verify this model experimentally in the case of low-speed modulation. A weak Gaussian probe field is sent into the constructed helical photonic lattices to image their structures under electromagnetically induced transparency (EIT). The motion trajectories of the sites on the discretized output patterns exhibit repeated circles, advocating the formation of rotating lattices. By introducing phase modulations to involved beams, we provide a continent way for producing transverse motions in waveguide arrays with reconfigurability in rotational direction, radius, and speed. This work looks forward to promising applications in topological photonics with great popularity.

Review on Grounds state Hanle effect on paraffin coated alkali atoms under condition EIT and EIA

IntroductionThis review is specifically aimed at a higher level of understanding of the ground-state Hanle effect through novel methods of atomic vapor interaction with resonant light. Electromagnetically Induced Transparency (EIT) and absorption (EIA) are the primary phenomena in this context. EIT is a process in which destructive interference at absorption frequencies within a medium is caused by a control laser and makes the medium clear to the probe laser light. It should be noted that this transparency is crucial for turning on/off the light pulses, slowing down or stopping in several cases, thus enhancing the effectiveness of atomic magnetometers. However, constructive interference that occurs in EIA raises the density of the medium, which is advantageous for profit-making precise measurements and the improvement of atomic clocks. ObjectiveThe objective of this study is to review the fundamental principles of the Hanle effect, EIT, EIA, and coating methods for alkali atoms. These principles and techniques are critical for improving the sensitivity and functionality of atomic magnetometers and other quantum devices. By understanding and leveraging these phenomena, significant progress has been made in the development of high-precision measurement tools and quantum technologies. ResultsAdvancements in atomic magnetometer sensitivity represent a rapidly growing area of interest, driving significant progress in the development of quantum devices. This review consolidates the existing knowledge and recent findings, offering a thorough understanding of the fundamental principles and practical applications of the Hanle effect, EIT, EIA, and coating methods for alkali atoms. This review highlights how advancements in EIT and EIA have contributed to the sensitivity improvements of atomic magnetometers, and underscores the importance of coating methods for maintaining system integrity and performance. These developments are essential to the evolution of modern quantum technologies and precision measurement devices.

Simultaneously measuring microwave electric fields at different frequencies by Rydberg-atom-based electrometry with Zeeman-resolved Autler–Townes splitting

We provide the simultaneous traceable measurements of microwave electric fields at two different frequencies by the electromagnetically induced transparency (EIT) and Autler–Townes (AT) splitting. A static magnetic field working together with a linearly polarized probe and coupling light prepares Rydberg atoms in Zeeman sublevels with maximal |mJ| in an atomic vapor cell. Using the EIT-AT splitting of these two maximal |mJ| states, the microwave electric fields at two different frequencies are simultaneously measured, in which their frequency difference can be adjustable within the linear range of magnetic field-induced level shifts. The proposed method provides a promising prospect for calibrating multiple microwave frequencies simultaneously in the future.

A Method of Laser Frequency Stabilization Based on the Effect of Linear Dichroism in Alkali Metal Vapors in a Modulated Transverse Magnetic Field

We present a method of laser frequency stabilization based on the linear dichroism signal in a transverse magnetic field. This method is similar to the DAVLL (Dichroic Atomic Vapor Laser Lock) method. It differs from DAVLL and from its existing modifications primarily by the fact that it uses signals of linearly polarized light caused by alignment, rather than circular refraction caused by orientation, and therefore allows us to obtain error signals at the magnetic field modulation frequency (or its second harmonic) by extremely simple means. The method allows the laser frequency to be stabilized in the vicinity of the low-frequency transition in the D1 line of Cs; it does not require strong magnetic fields or careful shielding of cells containing cesium atoms. Although the absorption line in a gas-filled cell is typically gigahertz wide, the achievable resolution, limited by the signal-to-noise ratio of photon shot noise, can reach units or tens of kilohertz in a one hertz bandwidth.

Strong interactions between integrated microresonators and alkali atomic vapors: towards single-atom, single-photon operation

Cavity quantum electrodynamics (cQED), the interaction of a two-level system with a high quality factor (Q) cavity, is a foundational building block in different architectures for quantum computation, communication, and metrology. The strong interaction between the atom and the cavity enables single-photon operation, which is required for quantum gates and sources. Cold atoms, quantum dots, and color centers in crystals are among the systems that have shown single-photon operations, but they require significant physical infrastructure. Atomic vapors, on the other hand, require limited experimental infrastructure and are hence much easier to deploy outside a laboratory, but they consist of an ensemble of moving atoms that results in short interaction times involving multiple atoms, which can hamper quantum operations. A solution to this issue can be found in nanophotonic cavities, where the optical mode is confined to a small volume and light-matter interaction is enhanced, so that fast single-atom, single-photon operations are enabled. In this work, we study the interaction of an atomically clad microring resonator (ACMRR) with different-sized ensembles of Rb atoms. We demonstrate strong coupling between an ensemble of ≈50 atoms interacting with a high quality factor (Q=4.3×105) ACMRR, yielding a many-atom cooperativity C=(5.5±0.3). We continue to observe signatures of atom-photon interaction for a few (<3) atoms, for which we observe saturation at the level of a few intracavity photons. Further development of our platform, which includes integrated thermo-optic heaters to enable cavity tuning and stabilization, should enable the observation of interactions between single photons and single atoms.

Rydberg states of alkali atoms in atomic vapour as SI-traceable field probes and communications receivers

Rydberg states of alkali atoms in atomic vapour as SI-traceable field probes and communications receivers

Chip-scale sub-Doppler atomic spectroscopy enabled by a metasurface integrated photonic emitter

We demonstrate chip-scale sub-Doppler spectroscopy in an integrated and fiber-coupled photonic-metasurface device. The device is a stack of three planar components: a photonic mode expanding grating emitter circuit with a monolithically integrated tilt-compensating dielectric metasurface, a microfabricated atomic vapor cell, and a mirror. The metasurface photonic circuit efficiently emits a 130 μm wide (1/e2 diameter) collimated surface-normal beam with only −6.3 dB loss and couples the reflected beam back into the waveguide and connecting fiber, requiring no alignment between the stacked components. We develop a simple model based on light propagation through the photonic device to interpret the atomic spectroscopy signals and explain spectral features covering the full Rb hyperfine state manifold. The demonstration of waveguide-to-waveguide coupling through the vapor cell paves the way for atomic ensembles to be used as components in complex photonic integrated circuits, allowing the unique properties of atomic systems to be available for future highly miniaturized optical devices and systems.

Direct generation of time-energy-entangled W triphotons in atomic vapor.

Entangled multiphoton sources are essential for both fundamental tests of quantum foundations and building blocks of contemporary optical quantum technologies. While efforts over the past three decades have focused on creating multiphoton entanglement through multiplexing existing biphoton sources with linear optics and postselections, our work presents a groundbreaking approach. We observe genuine continuous-mode time-energy-entangled W-class triphotons with an unprecedented production rate directly generated through spontaneous six-wave mixing (SSWM) in a four-level triple-Λ atomic vapor cell. Using electromagnetically induced transparency and coherence control, our SSWM scheme allows versatile narrowband triphoton generation with advantageous properties, including long temporal coherence and controllable waveforms. This advancement is ideal for applications like long-distance quantum communications and information processing, bridging single photons and neutral atoms. Most importantly, our work establishes a reliable and efficient genuine triphoton source, facilitating accessible research on multiphoton entanglement.

CoOMBE: A suite of open-source programs for the integration of the optical Bloch equations and Maxwell-Bloch equations

The programs described in this article and distributed with it aim (1) at integrating the optical Bloch equations governing the time evolution of the density matrix representing the quantum state of an atomic system driven by laser or microwave fields, and (2) at integrating the 1D Maxwell-Bloch equations for one or two laser fields co-propagating in an atomic vapour. The rotating wave approximation is assumed. These programs can also be used for more general quantum dynamical systems governed by the Lindblad master equation. They are written in Fortran 90; however, their use does not require any knowledge of Fortran programming. Methods for solving the optical Bloch equations in the rate equations limit, for calculating the steady-state density matrix and for formulating the optical Bloch equations in the weak probe approximation are also described. Program summaryProgram Title: CoOMBECPC Library link to program files:https://doi.org/10.17632/5wsg9d52dk.1Developers' repository link:https://github.com/durham-qlm/CoOMBELicensing provisions: GPLv3Programming language: Fortran 90Nature of problem: The present programs can be used for the following operations: (1) Integrating the optical-Bloch equations within the rotating wave approximation for a multi-state atomic system. At the choice of the user, the calculation will return either the time-dependent density matrix at given times or the density matrix in the long time limit if the system evolves into a steady state in that limit. The calculation can be done with or without averaging over the thermal velocity distribution of the atoms. The number of atomic states which can be included in the calculation is limited only by the CPU time available and possibly by memory requirements. An arbitrarily large number of laser or microwave fields can be included in the calculation if these fields are all CW. This number is currently limited to one or two for fields that are not all CW. The calculation can be done in the weak probe approximation, or in the rate equations approximation, or without assuming either of these two approximations. Calculating refractive indexes, absorption coefficients and complex susceptibilities is also possible. (2) Integrating the 1D Maxwell-Bloch equations in the slowly varying envelope approximation for one or two fields co-propagating in a single-species atomic vapour. Although geared towards the case of atoms interacting with laser fields, this code can also be used for more general quantum systems with similar equations of motion (e.g., molecular systems, spin systems, etc.).Solution method: The Lindblad master equation is expressed as a system of homogeneous first order linear differential equations, which are transformed as required and solved to obtain the density matrix representing the state of the atomic system. A variety of methods are offered to this end. The same approach is also used in the calculation of the polarisation of the medium when integrating the Maxwell-Bloch equations. The latter are integrated over space using predictor-corrector methods. The library includes a general driving program making it possible to use these codes without additional program development. The distribution also includes examples of the use of a container for running these programs without a pre-installed Fortran compiler.

EVALUATION AND RISK ASSESSMENT OF TRACE METAL IN Solanum aethiopicum GROWN AROUND MECHANIC WORKSHOPS IN UMUAHIA ABIA STATE, NIGERIA.

The careless dumping of waste from automobile workshops has significantly increased the concentration of trace metals in the surrounding environment. This study investigated the health risk assessment associated with Solanum aethiopicum fruit consumption. Soil and Solanum aethiopicum, plant from Umuahia automobile workshop were analyzed for As, Cd, Cr, Cu, Fe, Hg, Li, Ni, Pb and Zn. This was done using Inductively Coupled Plasma Optical Emission Spectrophotometer (ICP-OES), while Hg was analysed using a Cold Vapour Atomic Fluorescence Spectrophotometer (CV-AFS) after acid digestion. The average concentration of As, Cd, Cu, Zn, Fe, Pb, Ni, Hg, Li and Cr in the fruit were 7.16±0.03, 1.68±0.16, 5.03±0.03, 19.45±0.32, 76.21±0.73, 6.23±0.45, 3.87±0.17, 0.0003±0.0001, 0.003±0.001 and 15.35±0.22 mg/kg, respectively. The HRI obtained for Cd was the highest 1.821 while the THQ was 1.82135. Fruit had trace metal concentrations higher than the USEPA, WHO, and FAO's approved permitted standards. Cd, Cr and Pb were determined to be the primary contributing factor linked to the development of health hazards and carcinogenic risk based on the results of the risk assessment. It is therefore appropriate to educate the public on the potential risks associated with consuming garden eggs from Umuahia automobile workshop.

Deep removal of Sn, Pb, and Sb in refined indium by vacuum distillation

To deeply separate the azeotropic impurities from the refined indium, three novel processes of vacuum distillation by considering the variables of vacuum pressure, loading mass, distillation time, temperature, and the effective vacuum evaporation area are firstly presented. Thermodynamic calculations show that Pb, Sb and Sn can be separated from indium melt by vacuum distillation due to their great difference in saturated vapor pressure and separation coefficient. Experiments show that distillation at 800 ℃ for 7 h under a pressure of 10−3 Pa could achieve the Pb concentration of 0.004 ppm in indium melt by enlarging the evaporation area and small ratio of h1/h4. After 950 ℃ distillation, the concentrations of Sb and Sn in the condensing indium reduced respectively from 0.15 ppm to 0.009 ppm, and 8.1 ppm to 0.05 ppm. Multiple processes of vacuum distillation were used to achieve the 7 N purity of indium, with the removal ratio of over 99.5 %. Besides, it is found out that when the temperature dropped from 1075 ℃ to 780 ℃, the movement stroke of vapor atoms reduced from 509 mm to 209 mm.