Double Radio-optical Resonance Research Articles

Double Radio-Optical Resonance in the Hanle Configuration under the Excitation of the D1 Absorption Line in Alkali Metal Atoms

Double Radio-Optical Resonance in the Hanle Configuration under the Excitation of the D1 Absorption Line in Alkali Metal Atoms

Microwave Magnetic Field Pattern Evaluation of Horn and Patch Antennas Using Cs Atomic Sensor

In this study, microwave (9.2 GHz) magnetic field radiation patterns of a horn antenna in the near-field (10 cm) and of a patch antenna in the near-field (3 mm, 2 cm) and far-field (10 cm) are measured using a Cs atomic sensor with $7\pi $ and $8~\sigma $ Zeeman double radio optical resonance (DROR) spectra at 6S1/2(F = 3, $\text{m}_{f}$ ) – 6S1/2 (F = 4, $\text{m}_{f}$ ) - 6P3/2(F = 4) transition by applying a 6 Gauss external magnetic field. Radiation patterns of a horn antenna and a patch antenna are characterized by measuring the DROR amplitude, while rotating the antennas 360 degrees relative to the atomic sensor, and the results are compared to patterns measured in the anechoic chamber using traditional methods. Radiation patterns in both polarizations are measured in a single full rotation, by measuring the $\pi $ and $\sigma $ Zeeman DROR fluorescence amplitudes at the same time. In addition, near-field microwave magnetic field radiation patterns of the patch antenna at orthogonal polarizations are measured at 3 mm distance by moving the antenna ±12.5 mm on the horizontal plane. Advantages and possible applications of small-sized atomic sensors in radiation pattern measurements at different polarizations and radiation analysis of complicated emitters such as circuit boards are discussed.

Raman − Ramsey pulsed excitation of coherent population trapping resonances in a 87Rb cell with a buffer gas

We report the results of experimental investigation of the Raman – Ramsey method of pulsed excitation of coherent population trapping (CPT) resonances in a rubidium vapour cell filled with a mixture of Ar and Ne buffer gases. For the development of compact quantum microwave frequency standards, this method is an alternative to the pulsed optical pumping method recently implemented using the same rubidium cell. Both methods have advantages over the traditional double radio-optical resonance technique, the main of which is the substantial suppression of the light shift of the clock transition frequency, since the evolution of the coherence of atomic states forming the clock transition occurs in the absence of laser radiation in the cell. The narrow (110 – 240 Hz) Raman – Ramsey resonances are obtained using the scheme of pulsed excitation of CPT resonances on the D1 lines of the 87Rb atom with the same linear (lin||lin) polarisations of the bichromatic laser radiation components. The process of optimising the central fringe linewidth, its contrast, and the linewidth-to-contrast ratio is described. The magnetic dependence of the Raman – Ramsey line central fringe linewidth is experimentally investigated.

Technique of pulsed optical pumping and pulsed excitation of microwave resonances using the Ramsey scheme in a 87Rb cell with a buffer gas

A laboratory prototype of a compact quantum frequency standard based on a rubidium vapour cell with pulsed laser pumping is developed. With significantly smaller overall dimensions (a volume of ∼10 L and a mass of ∼10 kg), the frequency standard is expected to have the short-term instability comparable with that of the commercial passive hydrogen masers and even the laboratory fountain-type atomic clocks based on cold atoms. The advantages of the technique of pulsed optical pumping and pulsed excitation of microwave resonances over the traditional techniques of double radio-optical resonance detection are substantiated. The results of the experimental study of pulsed optical pumping of a rubidium cell with a mixture of buffer Ar – Ne gases implemented at the VNIIFTRI are presented, the Ramsey resonances are obtained, and the process of optimising the contrast of the central resonance peak is described.

Solitary Line of Double Radio-Optical Magnetic Resonance in Atoms of 87Rb

Theoretical and experimental study of influence of quadratic Zeeman effect on the structure of double radio-optical resonance is presented. A specific transition in 87Rb atom is considered in the case of excitation with linearly polarized laser radiation and detection of the signal at the second harmonic of the AC magnetic field frequency. It is shown, that for small magnetic fields the magnetic resonance consists of a solitary line similarly to resonance in potassium [1]. However, for magnetic fields greater than 50μT the line acquires two additional side-peaks without breaking its symmetry and changingposition of resonance center. The described scheme can be used in magnetometry.

Variants of the light pulses controlling under conditions of double radio-optical resonance

On the bases of semi-classical theory of the laser light interaction with a cold atomic cloud, specifically, of the electromagnetically induced transparency (EIT), repeated reproduction and modulation of the light pulses are investigated. A scheme of the light pulses control by the use of radio-frequency (RF) pulses is shown to be very effective. Short RF pulses of appropriate areas stimulate repeated playbacks of the output light pulses similar to the input one.

Resonant Addressing and Manipulation of Silicon Vacancy Qubits in Silicon Carbide

Several systems in the solid state have been suggested as promising candidates for spin-based quantum information processing. In spite of significant progress during the last decade, there is a search for new systems with higher potential [D. DiVincenzo, Nat. Mater. 9, 468 (2010)]. We report that silicon vacancy defects in silicon carbide comprise the technological advantages of semiconductor quantum dots and the unique spin properties of the nitrogen-vacancy defects in diamond. Similar to atoms, the silicon vacancy qubits can be controlled under the double radio-optical resonance conditions, allowing for their selective addressing and manipulation. Furthermore, we reveal their long spin memory using pulsed magnetic resonance technique. All these results make silicon vacancy defects in silicon carbide very attractive for quantum applications.

Sensing of RF Magnetic Fields Using Zeeman Splitting of Double Radiooptical Resonance and a New Approach to Helmholtz Coil Calibrations

We experimentally investigated the resonance interaction of laser, microwave, and radio frequency (RF) fields with Cesium (133Cs) atomic gas. The observed Zeeman components produced by means of an external static magnetic field on the double radiooptical resonance (DROR) were used as a frequency-adjustable RF field detection sensor based on the laser spectroscopy technique. The change in the RF interaction frequency of Zeeman components with the increasing level of the static magnetic field was investigated and linear dependence of the RF interaction frequency of the Zeeman components on the external static magnetic field was observed. In addition, the change in the amplitude of the Zeeman components with the level of RF fields was investigated and an approximately linear relation in certain regions was detected. We also studied the relation of the Zeeman component amplitudes with laser and microwave powers. Finally, a new approach to Helmholtz coil calibrations by using this atomic sensor is discussed.

Toward Absolute Measurements of Far-Field Microwave Magnetic Field by Atomic Sensor Based on Double Radiooptical Resonance

By using Cs atomic sensor, the differences between the measurement results of double radiooptical resonance (DROR) and the ratio of Doppler amplitude to DROR signal (Doppler/DROR) for the far-field microwave magnetic field were illustrated experimentally. The effects of laser power and atomic sensor temperature to the DROR and Doppler/DROR ratio were investigated. At constant laser power, Cs atomic cell temperature and microwave magnetic field strength, the maximum deviations for DROR and Doppler/DROR ratio were calculated over time. The fluctuation of the Doppler/DROR ratio measurement results was calculated approximately as 0.5 dB in 24-h measurement time interval. On the other hand, the fluctuation of the measured DROR values was calculated as 0.9 dB in the same time interval. As a consequence, Doppler/DROR ratio measurements yield better and repeatable results by comparison with DROR measurements.

Characterization of a Far-Field Microwave Magnetic Field Strength Sensor Based on Double Radiooptical Resonance

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We experimentally investigated the resonance interaction of laser and microwave fields with <formula formulatype="inline"><tex Notation="TeX">$^{133}$</tex></formula>Cs atomic gas in far-field and free-space conditions. The observed double radiooptical resonance (DROR) on the D<formula formulatype="inline"><tex Notation="TeX">$_2$</tex></formula> line of Cs atoms was used as a novel-type field sensor, based on the laser spectroscopy technique, for the detection and investigation of the time-varying magnetic field. The effects of the Cs cell length, both laser and microwave powers, and their polarizations to the changing amplitude of the DROR signal were investigated. Almost linear dependencies of the DROR signal amplitude with both laser and microwave powers have been observed. The splitting of DROR signal under a constant magnetic field was detected. The time response of the sensor system was investigated under pulsed microwave. The amplitude fluctuation of the microwave magnetic field was measured using the DROR signal and the isotropic probe simultaneously. The stability of amplitude fluctuations of the microwave field with time was analyzed by using Allan variance statistics. </para>

Laser pumping methods in cesium and rubidium atoms in new generations of highly stable industrial quantum frequency standards

Theoretical and experimental studies have been made on laser pumping in quantum discriminators containing rubidium and cesium vapor cells, including double radio-optical resonance, light shifts of frequency, quality parameters, frequency instability, and so on. Good agreement is shown between the theoretical and experimental results, which may serve as the scientific basis for constructing new generations of quantum frequency standards with elevated metrological characteristics.

Double radio-optical resonance in 87RB atomic vapour in a finite-size bufferless cell

We study theoretically the formation of a double radio-optical resonance (DROR) in 87Rb vapour in a cell with an anti-relaxation coating. We develop a quantum-kinetic approach to the study of the Dicke narrowing. We examine various DROR schemes for different polarizations of the laser radiation. We find that the short-term stability σy of a DROR-based frequency standard improves significantly (by an order of magnitude) if a laser with a broad spectrum is used, in comparison to the case of excitation by a narrow-band laser radiation, and reaches ultimately the value σy ∼ 1 × 10−14 τ−1/2, where τ is the integration time (in seconds).

Shape of the signal of double radio-optical resonance in 85Rb atomic vapors in strong fields

A transmission peak has been experimentally observed in the center of the signal of double radio-optical resonance in rubidium atomic vapors at the hyperfine splitting frequency of the ground state. It has been shown that this structure appears due to the Doppler detuning of the optical field and the corresponding optical shift of the microwave field. An analytical expression has been obtained for the shape of this resonance and the effect has been qualitatively explained.

Double radio–optical resonance in alkali metal vapors subjected to laser excitation

An investigation was made of a double radio–optical resonance (DROR) in a multilevel system of the alkali metal type. Equations for the density matrix were solved to obtain expressions for the signal, DROR line width, and shift of the maximum of DROR line peak. A study was made of the principal characteristics of a DROR in an optically dense medium in the form of a rubidium vapor. The ultimate short-term frequency instability of a rubidium discriminator was estimated to be 2 × 10 − 14 t − 1/2. Several experiments were carried out using an injection laser as an optical pump source. The results of the measurements yielded a short-term instability of 3 × 10 − 12 t − 1/2. An investigation was made of the optical frequency shift and an anomalous dependence of the shift on the intensity was observed. The results of the experimental and theoretical investigations were compared. The requirements for stabilization of the DROR parameters needed to reduce the frequency instability of a rubidium discriminator to the 10 − 14 level were identified.

CURRENT METHODS FOR THE STUDY OF THE STARK EFFECT IN ATOMS

CONTENTS I. Introduction 637 II. Theory of the Stark Effect 638 1. The Stark Effect in a Constant Electric Field 638 2. The Stark Effect in Alternating Electric Fields 640 III. The Study of the Stark Effect in a Constant Electric Field 643 1. Observation of the Shifts of Centers of Gravity of Absorption Lines in Atomic Beams 643 2. Study of the Stark Effect by Observation of Electric Double Refraction 644 3. Study of the Stark Effect by the Method of Comparison with Hyperfine Splitting 646 4. Observation of the Stark Effect by Radiospectroscopic Methods 646 5. Study of the Stark Effect by the Method of Double Radiooptical Resonance 647 6. Observation of the Stark Effect by Level-crossing and Beat Methods 649 IV. The Study of the Stark Effect in Fields of Optical Frequency 651 1. Observation of Shifts and Splittings of Levels of the Ground State of Hg199 by Resonance Light 651 2. Observation of Shifts and Splittings of Levels of Potassium Atoms in the Radiation Field of a Ruby Laser 653 V. Conclusion 654 Literature Cited 656