Rabi Resonance Research Articles

Study of Saturation Properties of an Inhomogeneous CW-EPR Line in the Vicinity of Rabi Resonance: Possible Application for B1 Estimation

Study of Saturation Properties of an Inhomogeneous CW-EPR Line in the Vicinity of Rabi Resonance: Possible Application for B1 Estimation

Using a single nitrogen-vacancy center in diamond to detect microwave magnetic field vectors at resonant frequency

This study introduces a method for reconstructing vector microwave magnetic fields using a single nitrogen-vacancy (NV) center in locally strong effective fields with two different orientations in diamond, without the previously required external magnetic field. Due to the varying orientations of the effective fields, NV centers exhibit two distinct sets of switchable ground states. The resonant Rabi oscillations of an NV center in these two distinct states were utilized to reconstruct vector microwave magnetic fields. Remarkably, this technique achieves an angular resolution of 0.02 mrad/Hz. Overcoming the limitations inherent in previous practices of using NV ensembles, this breakthrough has the potential to substantially enhance both the spatial resolution and the sensitivity of microwave magnetic field imaging, a meaningful development for various scientific and technological applications.

Dynamic Fabry-Pérot cavity stabilization technique for atom-cavity experiments

We present a stabilization technique developed to lock and dynamically tune the resonant frequency of a moderate finesse Fabry-Pérot (FP) cavity used in precision atom-cavity quantum electrodynamics (QED) experiments. Most experimental setups with active stabilization either operate at one fixed resonant frequency or use transfer cavities to achieve the ability to tune the resonant frequency of the cavity. In this work, we present a simple and cost-effective solution to actively stabilize an optical cavity while achieving a dynamic tuning range of over 100 MHz with a precision under 1 MHz. Our unique scheme uses a reference laser locked to an electro-optic modulator (EOM) shifted saturation absorption spectroscopy (SAS) signal. The cavity is locked to the PDH error signal obtained from the dip in the reflected intensity of this reference laser. Our setup provides the feature to efficiently tune the resonant frequency of the cavity by only changing the EOM drive without unlocking and re-locking either the reference laser or the cavity. We present measurements of precision control of the resonant cavity frequency and vacuum Rabi splitting (VRS) to quantify the stability achieved and hence show that this technique is suitable for a variety of cavity QED experiments.

Phase-Driving Hole Spin Qubits.

The spin-orbit interaction in spin qubits enables spin-flip transitions, resulting in Rabi oscillations when an external microwave field is resonant with the qubit frequency. Here, we introduce an alternative driving mechanism mediated by the strong spin-orbit interactions in hole spin qubits, where a far-detuned oscillating field couples to the qubit phase. Phase-driving at radio frequencies, orders of magnitude slower than the microwave qubit frequency, induces highly nontrivial spin dynamics, violating the Rabi resonance condition. By using a qubit integrated in a silicon fin field-effect transistor, we demonstrate a controllable suppression of resonant Rabi oscillations and their revivals at tunable sidebands. These sidebands enable alternative qubit control schemes using global fields and local far-detuned pulses, facilitating the design of dense large-scale qubit architectures with local qubit addressability. Phase-driving also decouples Rabi oscillations from noise, an effect due to a gapped Floquet spectrum and can enable Floquet engineering high-fidelity gates in future quantum processors.

A Ramsey apparatus for proton spins in flowing water

We present an apparatus that applies Ramsey’s method of separated oscillatory fields to proton spins in water molecules. The setup consists of a water circuit, a spin polarizer, a magnetically shielded interaction region with various radio frequency elements, and a nuclear magnetic resonance system to measure the spin polarization. We show that this apparatus can be used for Rabi resonance measurements and to investigate magnetic and pseudomagnetic field effects in Ramsey-type precision measurements with a sensitivity below 100 pT.

Toward High‐Throughput Single‐Spin Optically Detected Magnetic Resonance Spectroscopy with Spatially Programmable Laser Illumination

AbstractThe single nitrogen‐vacancy (NV) centers in diamond are shown as a quantum sensor with broad applications in nanoscale sensing of magnetic field, electric field, temperature, and strain. However, the basic technique, namely, optically detected magnetic resonance to manipulate and measure single NV centers needs to be highly sped up for broad and practical applications. Here, this work shows a parallel optically detected magnetic resonance (ODMR) platform of single NV centers including the programmable excitation laser spots generated by a digital micromirror device, a four‐channel uniform microwave delivery, and the fluorescence detector based on scientific complementary metal–oxide–semiconductor camera. In the viewing field of 26 µm, hundreds of distinguishable fluorescent spots are addressed and 413 NV center spots are recognized. The magnetic resonance spectrum, Rabi oscillation, and spin echo of each NV center spot are measured in parallel. As a result, a preliminary speedup of ≈20‐fold is achieved compared to the confocal‐based ODMR and can be further extended to thousands of folds after updating the digital micromirror device and camera.

High-dynamic-range microwave sensing using atomic Rabi resonances.

Detection of the microwave (MW) field with high accuracy is very important in the physical science and engineering fields. Herein, an atomic Rabi resonance-based MW magnetic field sensor with a high-dynamic-range is reported, where α and β Rabi resonances are used to measure MW fields. In MW measurement experiments, the sensor successfully measured a magnetic field of about 10 nT at 9.2GHz using the α Rabi resonance line on the cesium clock transition and continuously detected the MW magnetic field in the X-band over a high dynamic power range of >60 dB from the β Rabi resonance. Finally, the MW power frequency shift and power broadening are investigated to support more sensitive field measurements. The proposed MW detection method can be extended to cover a higher dynamic range and a wider frequency band by applying stronger excitations and exploring non-clock atomic transitions, respectively. In addition to MW magnetic field sensing, other potential application of the proposed method can be explored, including SI-traceable MW calibration and atomic communication.

Multiband Rabi antenna using nest microstrip add-drop filter (NMADF) for relativistic sensing applications

A microstrip circuit is designed, constructed, and tested based on the nest microstrip add-drop filters (NMADF). The multi-level system oscillation is generated by the wave-particle behaviors of AC driven along the microstrip ring circular path. The continuous successive filtering is applied via the device input port. The higher-order harmonic oscillations can be filtered, from which the two-level system known as a Rabi oscillation is achieved. The outside microstrip ring energy is coupled to the inside rings, from which the multiband Rabi oscillations can be formed within the inner rings. The resonant Rabi frequencies can be applied for multi-sensing probes. The relationship between electron density and Rabi oscillation frequency of each microstrip ring output can be obtained and used for multi-sensing probe applications. The relativistic sensing probe can be obtained by the warp speed electron distribution at the resonant Rabi frequency respecting the resonant ring radii. These are available for relativistic sensing probe usage. The obtained experimental results have shown that there are 3-center Rabi frequencies obtained, which can be used for 3-sensing probes simultaneously. The sensing probe speeds of 1.1c, 1.4c, and 1.5c are obtained using the microstrip ring radii of 14.20, 20.12, and 34.49 mm, respectively. The best sensor sensitivity of 1.30 ms is achieved. The relativistic sensing platform can be used for many applications.

Atom-based sensing technique of microwave electric and magnetic fields via a single rubidium vapor cell.

We present an atom-based approach for determining microwave electric and magnetic fields by using a single rubidium vapor cell in a microwave waveguide. For a 87Rb cascade three-level system employed in our experiment, a weak probe laser driving the lower transition, 5S1/2→5P3/2, is first used to measure the microwave magnetic field based on the atomic Rabi resonance. When a counter-propagating strong coupling laser is subsequently turned on to drive the Rydberg transition, 5P3/2→67D5/2, the same probe laser is then used as a Rydberg electromagnetically induced transparency (EIT) probe to measure the microwave electric field by investigating the resonant microwave dressed Autler-Townes splitting (ATS). By tuning the hyperfine transition frequency of the ground state using an experimentally feasible static magnetic field, we first achieved a measurement of the microwave electric and magnetic field strength at the same microwave frequency of 6.916 GHz. Based on the ideal relationship between the electric and magnetic field components, we obtained the equivalent microwave magnetic fields by fitting the inversion to the measured microwave electric fields, which demonstrated that the results were in agreement with the experimental measurement of the microwave magnetic fields in the same microwave power range. This study provides new experimental evidence for quantum-based microwave measurements of electric and magnetic fields by a single sensor in the same system.

Структура и особенности автомодуляции сверхизлучательных состояний в асимметричном резонаторе Фабри-Перо

The dependence of the structure and stability of strongly asymmetric stationary states of a superradiant laser with a slightly asymmetric low-Q Fabry-Perot cavity on its length, reflection factors of mirrors, and pumping level is studied. The states are related to a self-consistent inhomogeneous half-wavelength population inversion grating. The possibility of the existence of two dynamic phase transitions from a stationary (monochromatic) state of this type to a nonstationary one is established: 1) a dissipative superradiant transition to a regime with a quasi-continuous lasing spectrum (in a weakly asymmetric cavity) and 2) a self-modulation transition to a regime with a discrete lasing spectrum. It is shown that the latter can be caused by excitation of both polariton and electromagnetic laser modes due to resonant Rabi oscillations of active centers with a sufficiently long phase relaxation time.

Photon and magnetic field controlled electron transport of a multiply-resonant photon-cavity double quantum dot system

We study electron transport through double quantum dots (DQD) coupled to a cavity with a single photon mode. The DQD is connected to two electron reservoirs, and the total system is under an external perpendicular magnetic field. The DQD system exhibits a complex multi-level energy spectrum. By varying the photon energy, several anti-crossings between photon dressed electron states of the DQD-cavity system are found at low strength of the magnetic field. The anti-crossings are identified as multiple Rabi resonances arising from the photon exchange between these states. As the results, a dip in the current is seen caused by the multiple Rabi resonances. By increasing the strength of the external magnetic field, a dislocation of the current dip to a lower photon energy is found and the current dip can be diminished. The interplay of the strength of the magnetic field and the geometry of the states the DQD system can weaken the multiple Rabi resonances in which the exchange of photon between the anti-crossings is decreased. We can therefore confirm that the electron transport behavior in the DQD-cavity system can be controlled by manipulating the external magnetic field and the photon cavity parameters.

Effects of coupling strength of the electron–photon and the photon–environment interactions on the electron transport through multiple-resonances of a double quantum dot system in a photon cavity

We study electron transport properties through a double quantum dot (DQD) system coupled to a single mode photon cavity, DQD-cavity. The DQD system has a complex multilevel energy spectrum, in which by tuning the photon energy several anti-crossings between the electron states of the DQD system and photon dressed states are produced, which have not been seen in a simple two level DQD system. Three different regions of the photon energy are studied based on anti-crossings, where the photon energy ranges are classified as “low”, “intermediate”, and “high”. The anti-crossings represent multiple Rabi-resonances, which lead to a current dip in the electron transport at the “intermediate” photon energy. Increasing the electron–photon coupling strength, gγ, the photon exchanges between the anti-crossing states are changed leading to a dislocation of the multiple Rabi resonance states. Consequently, the current dip at the intermediate photon energy is further reduced. Additionally, we tune the cavity–environment coupling, κ, to see how the transport properties in the strong coupling regime, gγ>κ, are changed for different directions of the photon polarization. Increasing κ with a constant value of gγ, a current enhancement in the intermediate photon energy is found, and a reduction in the current is seen for the “high” photon energy range. The current enhancement in the intermediate photon energy is caused by the weakening of the multiple Rabi-resonance in the system.

Microwave magnetic field strength imaging based on Rabi resonance with alkali-atom vapor cell

The present Rabi resonance microwave sensing technique cannot fully describe the microwave magnetic field strength distribution due to the signal detection method. Here, we propose an alternative Rabi resonance-based microwave imaging technique using a digital micromirror device and an alkali atomic cell. The experimental results well describe the distribution of the microwave field quantitatively and agree with the absorption imaging results. This technique can also be used as a method to analyze and measure the relaxation rate in an atomic vapor cell and offers a SI-traceable imaging approach for the microwave magnetic field. Its simple architecture holds great potential for the development of compact/miniature microwave field sensors.

Edge-mode polariton chains in the dielectric whispering gallery modes and two-dimensional material’s topological system

Topological polaritons are a new topological phenomenon that has a combination of advantages such as strong nonlinearity, low effective mass, and topological invariants. However, the actual configurations of topological polaritons based on two-dimensional materials have not been discussed yet. In this paper, we theoretically demonstrate a Su-Schrieffer-Heeger (SSH) model (Sinev et al 2015 Nanoscale 7 11904; Dobrykh et al 2018 Phys. Rev. Lett. 121 163901; Qi et al 2020 Phys. Rev. A 102 022404) with topological polaritons by TiO2 whispering gallery modes and nanodisk arrays coupled with two-dimensional transition metal dichalcogenides (TMDCs) exciton materials. The transverse electric-polarized strong evanescent fields around the TiO2 nanodisks coupled with the TMDCs excitons for each atom can construct strong coupling between exciton-polaritons with a distinct resonant Rabi splitting dispersion of approximately 14 nm. By changing the distance between adjacent nanodisks, we observed obvious edge states for the SSH polariton chain at the wavelength of polaritons. This study paves the way toward new topological polaritons in large nonlinear devices with an edge transport based on two-dimensional materials.

Deep-Learning-Enhanced Single-Spin Readout in Silicon Carbide at Room Temperature

Defect spin qubits in silicon carbide have recently drawn widespread attention. Extraction of spin information in the presence of noise always requires multiple repeated measurements, which consumes a large amount of time resources. In this paper, we propose a deep-learning-enhanced method to extract effective parameters from continuous-wave optically detected magnetic resonance (ODMR) spectra and Rabi oscillations with less time consumption. Even if the signal-to-noise ratio is reasonably low, a well-trained convolutional neural network (CNN) can predict the resonance peaks of ODMR spectra or the period of Rabi oscillations. Because of the fast output of predictions by the CNN, this method can be used to sense the magnetic field in the environment and microwave intensities in real time.

CW-EPR spectra of P1 centers in HPHT diamond in the vicinity of Rabi resonance: possible standard for [formula omitted] evaluation in EPR and DNP enhanced NMR spectroscopies

Synthetic commercial type-IIa diamond crystal containing low concentration of P1 (Ns0) centers ([Ns0] <1ppm) was examined as a possible calibration standard for evaluating microwave magnetic field intensity (B1) in the spectrometer cavity. The reliability of this standard was experimentally and theoretically tested by employing two different types of microwave cavities with different distributions of B1 values. The procedure relies on the ordinary continuous wave electron paramagnetic resonance (CW-EPR) with magnetic field modulation (ωrf/2π=100 kHz) applied under the regime of the microwave power (PMW) saturation of the out-of-phase first harmonic signal. The power saturation procedure for PMW∼B11/2 was analyzed with respect to the change of spectral lineshape when Rabi frequency (ω1=γB1, γis the electron gyromagnetic ratio) approaches to ωrf. The phenomenon of the inversion of sideband lines while passing the Rabi resonance condition (ω1=ωrf) was analyzed. In specific, from the simulation of the experimental lineshapes in the close vicinity of Rabi resonance (ω1≈ωrf) the correspondingB1 can be assigned. For the chosen diamond crystal low value of B1≈3.6µT at Rabi resonance was determined what makes it a convenient standard for DNP enhanced NMR spectroscopy which requires relatively small B1.

Hook-and-Loop laser fastening of an optical frequency comb to a strongly driven two-level quantum system

In order to control the state of a two-level quantum system (e.g. the spin state of an ion qubit), optical frequency combs perform a two-photon stimulated Raman process through stimulated absorption from one comb tooth and stimulated emission into another comb tooth. If the two-level energy gap is an integer multiple of the repetition rate of the laser, resonant Rabi oscillations are excited. When these latter have a frequency close to the qubit’s transition one, a strongly anharmonic phase-locked cycle may exist on the Bloch sphere, which generates a sub-harmonic series of very narrow, equally spaced, spectral lines. If the repetition rate of an optical frequency comb is appropriately tuned to these latter (up to the average carrier envelope frequency), a highly resonant dynamical regime of the two-level system should be reached where the Raman stimulated absorption and emission processes would occur for any pair of adjacent comb teeth.

Lifetime of the ^{2}F_{7/2} Level in Yb^{+} for Spontaneous Emission of Electric Octupole Radiation.

We report a measurement of the radiative lifetime of the ^{2}F_{7/2} level of ^{171}Yb^{+} that is coupled to the ^{2}S_{1/2} ground state via an electric octupole transition. The radiative lifetime is determined to be 4.98(25)×10^{7} s, corresponding to 1.58(8)yr. The result reduces the relative uncertainty in this exceptionally long excited state lifetime by 1 order of magnitude with respect to previous experimental estimates. Our method is based on the coherent excitation of the corresponding transition and avoids limitations through competing decay processes. The explicit dependence on the laser intensity is eliminated by simultaneously measuring the resonant Rabi frequency and the induced quadratic Stark shift. Combining the result with information on the dynamic differential polarizability permits a calculation of the transition matrix element to infer the radiative lifetime.

Quantum Zeno Jumps in a Resonantly Driven Qubit under Frequent Measurements

In Nature, 570, 200 (2019), Minev and co-authors’ experiment shows how to deterministically “catch and reverse a quantum jump mid-flight” in a continuously-observed Rabi-stimulated qubit. Its interpretation is in debate (La Recherche, 555, 40, (2020)). We show that the quantum Zeno effect (QZE) of continuous measurement —by use of photon emission from a 3rd high-rate monitored ancilla level— can be described by an action-angle canonical transformation of the original Hamiltonian dynamical system (HDS) theory of QZE. Then energy whose mean value yields the well-known resonant Rabi harmonic dynamics is actually defined by large-amplitude high-frequency oscillations of the internal as well as of the overall phase of the two-level system. By making use of their standard deviation, we show that the separatrix crossing of the HDS trajectory yields the quantized action nh where n = 1, 2, 3 .... Therefore, the jump dynamics observed in Minev et al. experiment belongs to a series of discrete quantum jumps: it corresponds in this experiment to n = 3.

Demonstration of Invariant‐Based Shortcuts to Coherent Population Transfer in a Superconducting Qutrit

Invariant‐based shortcuts to adiabaticity (IB‐STA) approach is demonstrated to speed up the coherent population transfer of a three‐level quantum system on a superconducting circuit. Compared with the conventional stimulated Raman adiabatic passage (STIRAP), the scheme can achieve the same high transfer efficiency with evolution time reduced by 5.96 times. The final transfer efficiency of the scheme is measured to be , which is mainly decoherence limited. Further, the robustness of the scheme is experimentally characterized, which is superior to the time‐optimal resonant Rabi scheme under systematic pulse amplitude error. Therefore, the approach provides an alternative approach to realize high‐fidelity state manipulation and preparation for weakly coupled Λ‐ or Ξ‐type quantum systems.