Hyperfine spectroscopy in a quantum-limited spectrometer
S. Probst, G. L. Zhang, M. Rančić, V. Ranjan, M. Le Dantec, Z. Zhong, B. Albanese, A. Doll, R. B. Liu, J. J. L. Morton, T. Chanelière, P. Goldner, D. Vion, D. Esteve, P. Bertet
We report measurements of electron spin echo envelope modulation (ESEEM) performed at millikelvin temperatures in a custom-built high-sensitivity spectrometer based on superconducting micro-resonators. The high quality factor and small mode volume (down to 0.2pL) of the resonator allow to probe a small number of spins, down to $5\cdot 10^2$. We measure 2-pulse ESEEM on two systems: erbium ions coupled to $^{183}$W nuclei in a natural-abundance $\text{CaWO}_4$ crystal, and bismuth donors coupled to residual $^{29}$Si nuclei in a silicon substrate that was isotopically enriched in the $^{28}$Si isotope. We also measure 3- and 5-pulse ESEEM for the bismuth donors in silicon. Quantitative agreement is obtained for both the hyperfine coupling strength of proximal nuclei, and the nuclear spin concentration.
We present the computation of two-photon transition spectra between ro-vibrational states of the H2+ molecular ion, including the effects of hyperfine structure and excitation polarization. The reduced two-photon matrix elements are obtained by means of a variational method. We discuss the implications of our results for high-resolution spectroscopy of H2+.
Using 201Hg+ contained within a linear quadrupole rf ion trap that is part of an atomic clock, we report the first high-resolution spectroscopy on the hyperfine structure of 201Hg+. We measure the absolute ground state hyperfine interval to be 29.954365821130(171)(62)(10) GHz, more than 8 orders of magnitude improvement over the previous measurement. The first error estimate in parentheses is the statistical error in the shifted line center measurement, the second is systematic uncertainty, and the third is calibration uncertainty in the hydrogen maser reference standard. By comparison to the …
In a frequency-modulation spectroscopy experiment, using the radiation from a single frequency diode laser, the spectra of molecular iodine hyperfine structure near 640 nm were recorded on the transition $B^3Π_{0_u^{+}}-X^1Σ^+_{g}$. The frequency reference given by the value of the modulation frequency (12.5 MHz in given experiment) allows determination of the frequency differences between hyperfine components with accuracy better than 0.1 MHz using the fitting procedure in experiment with only one laser.
We present an accurate computation of the g-factors of the hyperfine states of the hydrogen molecular ion H2+. The results are in good agreement with previous experiments, and can be tested further by rf spectroscopy. Their implication for high-precision two-photon vibrational spectroscopy of H2+ is also discussed. It is found that the most intense hyperfine components of two-photon lines benefit from a very small Zeeman splitting.
Measurements of hyperfine polarization quantum beats are used determine the magnetic dipole (A) and electric quadrupole (B) coupling constants in the excited atomic Cs 8p level. The experimental approach is a novel combination of pulsed optical pumping and time-delayed stimulated emission probing of the excited level. From the measured evolution of the atomic linear polarization degree as a function of probe delay time, we determine the hyperfine coupling constants A = 7.42(6) MHz and B = 0.14(29) MHz.
High-resolution Zeeman spectroscopy of electronic-nuclear hyperfine levels of ${^5\mathrm{I}_8}\rightarrow{^5\mathrm{I}_7}$ transitions in Ho$^{3+}$:Y$_2$SiO$_5$ is reported. Crystal-field parameters determined for the two $C_1$ symmetry sites in Er$^{3+}$:Y$_2$SiO$_5$ are successfully used to model the Zeeman-hyperfine data, including the prediction of avoided crossings between hyperfine levels under the influence of an external magnetic field. The two six- and seven-coordinate substitutional sites may be distinguished by comparing the spectra with crystal-field calculations.
We perform spectroscopy on the hyperfine splitting of $^{85}$Rb atoms trapped in far-off-resonance optical traps. The existence of a spatially dependent shift in the energy levels is shown to induce an inherent dephasing effect, which causes a broadening of the spectroscopic line and hence an inhomogeneous loss of atomic coherence at a much faster rate than the homogeneous one caused by spontaneous photon scattering. We present here a number of approaches for reducing this inhomogeneous broadening, based on trap geometry, additional laser fields, and novel microwave pulse sequences. We then sh…
High precision spectroscopy of the $^1S_0$-to-${^1}D_2$ clock transition of $^{176}$Lu is reported. Measurements are performed with Hertz level precision with the accuracy of the hyperfine-averaged frequency limited by the calibration of an active hydrogen maser to the SI definition of the second via a GPS link. The measurements also provide accurate determination of the $^1D_2$ hyperfine structure. Hyperfine structure constants associated with the magnetic octupole and electric hexadecapole moments of the nucleus are considered, which includes a derivation of correction terms from third-order…
We report on spectroscopic results on the $^2S_{1/2} \rightarrow\,^2P_{3/2}$ transition in single trapped Yb$^+$ ions. We measure the isotope shifts for all stable Yb$^+$ isotopes except $^{173}$Yb$^+$, as well as the hyperfine splitting of the $^2P_{3/2}$ state in $^{171}$Yb$^+$. Our results are in agreement with previous measurements but are a factor of 5-9 more precise. For the hyperfine constant $A\left(^2P_{3/2}\right) = 875.4(10)$ MHz our results also agree with previous measurements but deviate significantly from theoretical predictions. We present experimental results on the branching …
Electron spin resonance (ESR) spectroscopy has broad applications in physics, chemistry and biology. As a complementary tool, zero-field ESR (ZF-ESR) spectroscopy has been proposed for decades and shown its own benefits for investigating the electron fine and hyperfine interaction. However, the ZF-ESR method has been rarely used due to the low sensitivity and the requirement of much larger samples than conventional ESR. In this work, we present a method for deploying ZF-ESR spectroscopy at the nanoscale by using a highly sensitive quantum sensor, the nitrogen-vacancy center in diamond. We also…
Hyperfine spectroscopy and fast, all-optical arbitrary state initialization and readout of a single, ten-level ${}^{73}$Ge vacancy nuclear spin qudit in diamond
We present the results of an experimental and theoretical study of the electronically excited $\tripletex$ state of $^{87}$Rb$_2$ molecules. The vibrational energies are measured for deeply bound states from the bottom up to $v'=15$ using laser spectroscopy of ultracold Rb$_2$ Feshbach molecules. The spectrum of each vibrational state is dominated by a 47\,GHz splitting into a $\cog$ and $\clg$ component caused mainly by a strong second order spin-orbit interaction. Our spectroscopy fully resolves the rotational, hyperfine, and Zeeman structure of the spectrum. We are able to describe to first…
Mid-infrared (mid-IR) spectroscopy is a crucial workhorse for a plethora of analytical applications and is suitable for diverse materials, including gases, polymers or biological tissue. However, this technologically significant wavelength regime between 2.5-10$μ$m suffers from technical limitations primarily related to the large noise in mid-IR detectors and the complexity and cost of bright, broadband mid-IR light sources. Here, using highly non-degenerate, broadband photon pairs from bright spontaneous parametric down-conversion (SPDC) in a nonlinear interferometer, we circumvent these limi…
Spectroscopy is a powerful tool to probe physical, chemical, and biological systems. Recent advances in microfabrication have introduced novel, intriguing mesoscopic quantum systems including superconductor-semiconductor hybrid devices and topologically non-trivial electric circuits. A sensitive, general purpose spectrometer to probe the energy levels of these systems is lacking. We propose an on-chip absorption spectrometer functioning well into the millimeter wave band which is based on a voltage-biased superconducting quantum interference device. We demonstrate the capabilities of the spect…
We measure the hyperfine structure of $nP_{1/2}$ Rydberg states using mm-wave spectroscopy on an ensemble of laser-cooled $^{85}$Rb atoms. Systematic uncertainties in our measurement from the Zeeman splittings induced by stray magnetic fields and dipole-dipole interactions between two Rydberg atoms are factored in with the obtained statistical uncertainty. Our final measurement of the $nP_{1/2}$ hyperfine coupling constant is $A_{\text{hfs}}=1.443(31)$~GHz. This measurement is useful for studies of long-range Rydberg molecules, Rydberg electrometry, and quantum simulation with dipole-dipole in…
We perform precision microwave spectroscopy--aided by Stark deceleration--to reveal the low magnetic field behavior of OH in its ^2Π_{3/2} ro-vibronic ground state, identifying two field-insensitive hyperfine transitions suitable as qubits and determining a differential Lande g-factor of 1.267(5)\times10^{-3} between opposite parity components of the Λ-doublet. The data are successfully modeled with an effective hyperfine Zeeman Hamiltonian, which we use to make a tenfold improvement of the magnetically sensitive, astrophysically important ΔF=\pm1 satellite-line frequencies, yielding 172052988…
