Radio-frequency Spectroscopy Research Articles

Radio-frequency spectroscopy and the dimensional crossover in interacting spin-polarized Fermi gases

Radio-frequency spectroscopy and the dimensional crossover in interacting spin-polarized Fermi gases

Floquet engineering of a dynamical Z2 lattice gauge field with ultracold atoms

Abstract Gauge field theory is a fundamental concept in modern physics, attracting many theoretical and experimental efforts towards its simulation. In this paper we propose that a simple model, in which fermions coupled to a dynamical lattice gauge field, can be engineered via the Floquet approach. The model possesses both an independent Maxwell term and local Z 2 gauge symmetry. Our proposal relies on a species-dependent optical lattice, and can be achieved in one, two or three dimensions. By a unitary transformation, this model can be mapped into a non-interacting composite fermion system with fluctuating background charge. With the help of this composite fermion picture, two characteristic observations are predicted. One is radio-frequency spectroscopy, which exhibits no dispersion in all parameter regimes. The second is dynamical localization, which depends on the structure of the initial states.

Two atoms in a harmonic trap with spin-orbital-angular-momentum coupling

We study the problem of two harmonically trapped atoms in the presence of spin-orbital-angular-momentum (SOAM) coupling. The two-body energy spectrum is numerically calculated by utilizing the exact diagonalization method. We analyze how the degeneracy of energy levels is lifted under the interplay between the interatomic interaction and SOAM coupling. The exact numerical results show excellent agreement with that of perturbation theory in the weak-interaction limit as well as that in the absence of SOAM coupling. The properties of correlations between the two atoms are also discussed with respect to the interaction strength. The findings in this paper may provide valuable insights into few-body physics subjected to SOAM coupling and the possible experimental detection of spectrum functions in many-body systems, such as radiofrequency spectroscopy. Published by the American Physical Society 2024

Evaluating the Effect of MarginProbe® Use on Re-excisions After Partial Mastectomy: A Single-Institution Analysis.

Breast conservation therapy is a widely accepted approach in treating breast cancer, yet the average re-excision rates are approximately 25% despite surgical advancements. The Food and Drug Administration (FDA)-approved MarginProbe® device uses radiofrequency spectroscopy for intraoperative margin assessment, potentially reducing re-excision rates. This study evaluated the effectiveness of MarginProbe® in reducing re-excisions compared with standard of care (SOC). A prospective cohort with MarginProbe® usage during partial mastectomies from June 2019 to July 2023 (153 patients) was compared with a retrospective control group without the device from January 2015 to May 2019 (300 patients). Both groups underwent partial mastectomies performed by two breast surgeons. Positive margins were defined as tumor on ink for invasive cancers and within 2 mm for ductal carcinoma in situ. When control was used for patient demographics and tumor characteristics, the findings showed that MarginProbe® significantly decreased the probability of re-excision by 58% (p<0.001), although it led to a higher shave volume, with an average of 9.8cc additional tissue removed compared with SOC (p < 0.001). Human epidermal growth factor 2 (HER2) positivity was significantly associated with increased odds of re-excision (p = 0.036). MarginProbe® demonstrated a sensitivity of 70.1% and a specificity of 47.5%. MarginProbe® is an effective adjunct for intraoperative margin assessment to decrease re-excision rates. However, patient selection is paramount. Given its significant increase in shave volume, women with small breasts may be at higher risk for poor cosmesis. Surgeons should exercise clinical judgement when determining the suitability of MarginProbe® use for patients undergoing breast conservation. Further research is necessary to refine MarginProbe®'s specificity and to optimize its clinical application.

Spectral Signatures of Vibronic Coupling in Trapped Cold Ionic Rydberg Systems.

Atoms and ions confined with electric and optical fields form the basis of many current quantum simulation and computing platforms. When excited to high-lying Rydberg states, long-ranged dipole interactions emerge which strongly couple the electronic and vibrational degrees of freedom through state-dependent forces. This vibronic coupling and the ensuing hybridization of internal and external degrees of freedom manifest through clear signatures in the many-body spectrum. We illustrate this by considering the case of two trapped Rydberg ions, for which the interaction between the relative vibrations and Rydberg states realizes a quantum Rabi model. We proceed to demonstrate that the aforementioned hybridization can be probed by radio frequency spectroscopy and discuss observable spectral signatures at finite temperatures and for larger ion crystals.

Cost minimization in breast conserving surgery: a comparative study of radiofrequency spectroscopy and full cavity shave margins

BackgroundIn an effort to minimize positive margins and subsequent re-excision after breast conserving surgery (BCS), many providers and facilities have implemented either a Full Cavity Shave (FCS) approach or adding the MarginProbe Radiofrequency Spectroscopy System.ObjectiveWe sought to create a functioning Pro-Forma for use by facilities and payers to evaluate and compare the cost savings of implementing FCS or MarginProbe based on personalized variable inputs.MethodsA decision tree demonstrating three possible surgical pathways, BCS, BCS + FCS, and BCS + MarginProbe was developed with clinical inputs for re-excision rate, mastectomy as 2nd surgery, rate of reconstruction, and rate of 3rd surgery derived by a literature review. A surgical pathway cost formula was created using the decision tree and financial inputs derived by utilizing the nation’s largest database of privately billed health insurance claims and Medicare claims data (fairhealth.org). Using the surgical pathway formula and financial inputs, a customizable Pro-Forma was created for immediate cost savings analysis of BCS + FCS and BCS + Marginprobe using variable inputs. Costs are from the perspective of third-party payers.ResultsUtilizing MarginProbe to reduce re-excisions for positive margins can be associated with better cost-savings than FCS due to the increased pathology processing costs by using an FCS approach. The reduction in re-excision provided by both FCS and MarginProbe offset their increased expense to various degrees with cost savings of each method improving as baseline re-excisions rates increase, until ultimately each may become cost-neutral or cost-prohibitive when compared to BCS alone. Our data suggest that in the privately insured population, MarginProbe provides a cost-savings over BCS alone when baseline re-excision rates are over 20% and that FCS becomes cost-saving when baseline re-excision rates are over 29%. For Medicare patients, MarginProbe provides a cost-savings when baseline re-excision rates exceed 34%, and FCS becomes cost-saving for re-excision rates over 52%. Our Pro-Forma allows an individual provider or institution to evaluate the cost savings of the FCS approach and/or utilization of the MarginProbe device such that the additional cost or cost-savings of utilizing one or both of these methods can be quickly calculated based on their facility’s volume and baseline re-excision rate.ConclusionsOur data suggest that utilizing either an FCS approach or the MarginProbe radiofrequency spectroscopy system may be a cost-saving solution to reducing the rate of re-excisions depending on a facility or practice’s surgical volume and baseline re-excision rate. The degree to which each of these interventions provides an added cost or cost-savings to healthcare payers can be evaluated by utilizing the Pro-Forma outlined herein with customizable variable inputs.

Robust and scalable rf spectroscopy in first-order magnetic sensitive states at second-long coherence time

Trapped-ion quantum sensors have become highly sensitive tools for the search of physics beyond the Standard Model. Recently, stringent tests of local Lorentz-invariance (LLI) have been conducted with precision spectroscopy in trapped ions (Pruttivarasin et al 2015 Nature 517 592–5, Megidish et al 2019 Phys. Rev. Lett. 122 123605, Sanner et al 2019 Nature 567 204–8, Dreissen et al 2022 Nat. Commun. 13 1–6) . We here elaborate on robust radio-frequency composite-pulse spectroscopy at second long coherence times in the magnetic sublevels of the long-lived state of a trapped 172Yb+ ion which is scalable to spatially extended multi-ion systems. We compare two Ramsey-type composite rf pulse sequences, a generalized spin-echo (GSE) sequence (Shaniv et al 2018 Phys. Rev. Lett. 120 103202) and a sequence based on universal rotations with 10 rephasing pulses (UR10) (Genov et al 2017 Phys. Rev. Lett. 118 133202) that decouple the energy levels from magnetic field noise, enabling robust and accurate spectroscopy. Both sequences are characterized theoretically and experimentally in the spin- electronic ground state of 172Yb+ and results show that the UR10 sequence is 38 (13) times more robust against pulse duration (frequency detuning) errors than the GSE sequence. We extend our simulations to the eight-level manifold of the state, which is highly sensitive to a possible violation of LLI, and show that the UR10 sequence can be used for high-fidelity Ramsey spectroscopy in noisy environments. The UR10 sequence is implemented experimentally in the manifold and a coherent signal of up to 2.5 s is reached. In (Dreissen et al 2022 Nat. Commun. 13 1–6) we have implemented this sequence and used it to perform the most stringent test of LLI in the electron–photon sector to date with a single Yb+ ion. Due to the high robustness of the UR10 sequence, it can be applied on larger ion crystals to improve tests of Lorentz symmetry further. We demonstrate that the sequence can also be used to extract the quadrupole moment of the meta-stable state, obtaining a value of which is in agreement with the value deduced from clock measurements (Lange et al 2020 Phys. Rev. Lett. 125 143201).

Antihydrogen and Hydrogen: Search for the Difference

Our universe consists mainly of regular matter, while the amount of antimatter seems to be negligible. The origin of this difference, known as the baryon asymmetry, remains undiscovered. Since the discovery of antimatter, many experiments have been carried out to study antiparticles and to compare matter and antimatter twins. Two of the most sensitive methods in physics, radiofrequency and optical spectroscopy, can be efficiently used to search for the difference. The successful synthesis and trapping of cold antihydrogen atoms opened the possibility of significantly increasing the sensitivity of matter/antimatter tests. This brief review focuses on a hydrogen/antihydrogen comparison using other independent spectroscopic measurements of single particles in traps and other simple atomic systems like positronium. Although no significant difference is detected in today’s level of accuracy, one can push forward the sensitivity by improving the accuracy of 1S–2S positronium spectroscopy, spectroscopy of hyperfine transition in antihydrogen, and gravitational measurements.

Evaluating the impact of radiofrequency spectroscopy on reducing reoperations after breast conserving surgery: A meta-analysis.

The benefits of breast conserving surgery for breast cancer patients are well established. To achieve adequate margins of excision, intraoperative management of breast margins is a critical factor through reducing reoperation for inadequate positive margin excision and associated morbidity and cost. Radiofrequency spectroscopy is a technology that could significantly reduce positive margins when used intraoperatively as an adjunct to other margin management methods. A meta-analysis was completed with 10 publications comparing use of radiofrequency spectroscopy technology (MarginProbe) with standard margin assessment procedures. Three randomized controlled studies and seven retrospective studies comparing MarginProbe to historical controls were included. The primary endpoint was reduction of re-excision rates. Statistical significance level was set at the two-sided 5% level corresponding to two-sided 95% confidence intervals (CIs) of the pooled relative risk estimates. A total of 2335 patients from 10 publications were included in this meta-analysis. The overall relative reduction in re-excision rate was 0.49 (95% CI: 0.38-0.64, p < 0.001). Statistical methods were used to examine publication bias. Despite the limited randomized controlled trials available comparing radiofrequency spectroscopy to standard operation procedures, the data from the 10 studies demonstrate a statistically significant reduction in re-excision rate of 49% for MarginProbe usage, currently the only technology indicated for intraoperative identification of breast cancer tissue at the lumpectomy specimen margin.

Raman spectroscopy of Fermi polarons

By using a non-self-consistent many-body $T$-matrix theory, we calculate the finite-temperature Raman spectroscopy of a mobile impurity immersed in a Fermi bath in three dimensions. The dependencies of the Raman spectrum on the transferred momentum, temperature, and impurity-bath interaction are discussed in detail. We confirm that the peak in the Raman spectrum shows a weaker dependence on the impurity concentration than that in the radio-frequency spectroscopy due to the nonzero transferred momentum, as anticipated. We compare our theoretical prediction with the recent measurement by Gal Ness et al. [G. Ness, C. Shkedrov, Y. Florshaim, O. K. Diessel, J. von Milczewski, R. Schmidt, and Y. Sagi, Phys. Rev. X 10, 041019 (2020)] without any adjustable parameters. At weak coupling, we find a good quantitative agreement. However, close to the Feshbach resonance the agreement becomes worse. At strong coupling, we find that an unrealistic Fermi bath temperature might be needed to account for the experimental data.

Low energy excitation spectrum of magic-angle semimetals

We theoretically study the excitation spectrum of a two-dimensional Dirac semimetal in the presence of an incommensurate potential. Such models have been shown to possess magic-angle critical points in the single particle wavefunctions, signalled by a momentum space delocalization of plane wave eigenstates and flat bands due to a vanishing Dirac cone velocity. Using the kernel polynomial method, we compute the single particle Green's function to extract the nature of the single particle excitation energy, damping rate, and quasiparticle residue. As a result, we are able to clearly demonstrate the redistribution of spectral weight due to quasiperiodicity-induced downfolding of the Brillouin zone creating minibands with effective mini Brillouin zones that correspond to emergent superlattices. By computing the damping rate we show that the vanishing of the velocity and generation of finite density of states at the magic-angle transition coincides with the development of an imaginary part in the self energy and a suppression of the quasiparticle residue that vanishes in a power law like fashion. Observing these effects with ultracold atoms using momentum resolved radiofrequency spectroscopy is discussed.

Contactless excitation of acoustic resonance in insulating wafers

Contactless excitation and detection of high harmonic acoustic overtones in a thin insulator single crystal are described using radio frequency spectroscopy techniques. Single crystal [001] silicon wafer samples were investigated, one side covered with a Nb thin film, the common starting point for the fabrication of quantum devices. The coupling between electromagnetic signals and mechanical oscillation is achieved from the Lorentz force generated by an external magnetic field. This method is suitable for any sample with a metallic surface or covered with a thin metal film. High resolution measurements of the temperature dependence of the sound velocity and elastic constants of silicon are reported and compared with known results.

Non-Hermitian Absorption Spectroscopy.

While non-Hermitian Hamiltonians have been experimentally realized in cold atom systems, it remains an outstanding open question of how to experimentally measure their complex energy spectra in momentum space for a realistic system with boundaries. The existence of non-Hermitian skin effects may make the question even more difficult to address given the fact that energy spectra for a system with open boundaries are dramatically different from those in momentum space; the fact may even lead to the notion that momentum-space band structures are not experimentally accessible for a system with open boundaries. Here, we generalize the widely used radio-frequency spectroscopy to measure both real and imaginary parts of complex energy spectra of a non-Hermitian quantum system for either bosonic or fermionic atoms. By weakly coupling the energy levels of a non-Hermitian system to auxiliary energy levels, we theoretically derive a formula showing that the decay of atoms on the auxiliary energy levels reflects the real and imaginary parts of energy spectra in momentum space. We further prove that measurement outcomes are independent of boundary conditions in the thermodynamic limit, providing strong evidence that the energy spectrum in momentum space is experimentally measurable. We finally apply our non-Hermitian absorption spectroscopy protocol to the Hatano-Nelson model and non-Hermitian Weyl semimetals to demonstrate its feasibility.

Exact Quasiparticle Properties of a Heavy Polaron in BCS Fermi Superfluids.

We present the Ramsey response and radio-frequency spectroscopy of a heavy impurity immersed in an interacting Fermi superfluid, using the exact functional determinant approach. We describe the Fermi superfluid through the conventional Bardeen-Cooper-Schrieffer theory and investigate the role of the pairing gap on quasiparticle properties revealed by the two spectroscopies. The energy cost for pair breaking prevents Anderson's orthogonality catastrophe that occurs in a noninteracting Fermi gas and allows the existence of polaron quasiparticles in the exactly solvable heavy impurity limit. Hence, we rigorously confirm the remarkable features such as dark continuum, molecule-hole continuum, and repulsive polaron. For a magnetic impurity scattering at finite temperature, we predict additional resonances related to the subgap Yu-Shiba-Rusinov bound state, whose positions can be used to measure the superfluid pairing gap. For a nonmagnetic scattering at zero temperature, we surprisingly find undamped repulsive polarons. These exact results might be readily observed in quantum gas experiments with Bose-Fermi mixtures that have a large-mass ratio.

Fermi polarons at finite temperature: Spectral function and rf spectroscopy

We present a systematic study of a mobile impurity immersed in a three-dimensional Fermi sea of fermions at finite temperature, by using the standard non-self-consistent many-body $T$-matrix theory that is equivalent to a finite-temperature variational approach with the inclusion of one-particle-hole excitation. The impurity spectral function is determined in the real-frequency domain, avoiding any potential errors due to the numerical analytic continuation in previous $T$-matrix calculations and the small spectral broadening parameter used in variational calculations. In the weak-coupling limit, we find that the quasiparticle decay rate of both attractive and repulsive polarons does not increase significantly with increasing temperature, and therefore Fermi polarons may remain well-defined far above Fermi degeneracy. In contrast, near the unitary limit with strong coupling, the decay rate of Fermi polarons rapidly increase and the quasiparticle picture breaks down close to the Fermi temperature. We analyze in detail the recent ejection and injection radio-frequency (rf) spectroscopy measurements, performed at Massachusetts Institute of Technology (MIT) and at European Laboratory for Non-Linear Spectroscopy (LENS), respectively. We show that the momentum average of the spectral function, which is necessary to account for the observed rf-spectroscopy, has a sizable contribution to the width of the quasiparticle peak in spectroscopy. As a result, the measured decay rate of Fermi polarons could be significantly larger than the calculated quasiparticle decay rate at zero momentum. By take this crucial contribution into account, we find that there is a reasonable agreement between theory and experiment for the lifetime of Fermi polarons in the strong-coupling regime, as long as they remain well-defined.

Radiofrequency spectroscopy with intraoperative pathological assessment for breast carcinoma: synergistic or redundant?

ABSTRACT Background Published MarginProbe (Dune Medical Devices Ltd., Israel) data reports ≥50% reduction in positive lumpectomy margins. We sought to determine whether adjunctive use of MarginProbe would provide value over intraoperative pathologic assessment alone. Methods This is a retrospective chart review of 86 consecutive lumpectomies with MarginProbe from December 2018 to November 2019. Margins were considered positive using ‘no ink on tumor’ guideline for invasive cancer, and 2 mm or greater for ductal carcinoma in-situ. Significance was measured using Fisher’s exact test. Results Seventy-six patients yielded 86 lumpectomies for inclusion. Mean age was 69.8 and mean tumor size was 1.09 cm. Sixty-eight invasive cancers were assessed using adjunct MarginProbe and gross assessment, while 18 ductal carcinoma in-situ cases utilized MarginProbe only. Among all cases, gross assessment alone reduced positive margins(29.2% relative reduction, p = 0.28). Utilizing both modalities, positive margins decreased from 27.9% to 9.3% (66.7% relative reduction, p < 0.01) representing a 46.9% relative reduction versus gross assessment alone. After gross assessment and MarginProbe evaluation, additional excised volume averaged 2.9 cc. Conclusions Synergistic use of MarginProbe and gross assessment reduces positive margins during breast conserving surgery. Surgeons can weigh its cost against it benefit with the succinct analysis we provide.

Emergence of a Sharp Quantum Collective Mode in a One-Dimensional Fermi Polaron

The Fermi-polaron problem of a mobile impurity interacting with fermionic medium emerges in various contexts, ranging from the foundations of Landau's Fermi-liquid theory to electron-exciton interaction in semiconductors, to unusual properties of high-temperature superconductors. While classically the medium provides only a dissipative environment to the impurity, quantum picture of polaronic dressing is more intricate and arises from the interplay of few- and many-body aspects of the problem. The conventional expectation for the dynamics of Fermi polarons is that it is dissipative in character, and any excess energy is rapidly emitted away from the impurity as particle-hole excitations. Here we report a strikingly different type of polaron dynamics in a one-dimensional system of the impurity interacting repulsively with the fermions. When the total momentum of the system equals the Fermi momentum, there emerges a sharp collective mode corresponding to long-lived oscillations of the polaronic cloud surrounding the impurity. This mode can be observed experimentally with ultracold atoms using Ramsey interferometry and radio-frequency spectroscopy.

Radiofrequency spectroscopy of one-dimensional trapped Bose polarons: crossover from the adiabatic to the diabatic regime

We investigate the crossover of the impurity-induced dynamics, in trapped one-dimensional Bose polarons subject to radio frequency (RF) pulses of varying intensity, from an adiabatic to a diabatic regime. Utilizing adiabatic pulses for either weak repulsive or attractive impurity-medium interactions, a multitude of polaronic excitations or mode-couplings of the impurity-bath interaction with the collective breathing motion of the bosonic medium are spectrally resolved. We find that for strongly repulsive impurity-bath interactions, a temporal orthogonality catastrophe manifests in resonances in the excitation spectra where impurity coherence vanishes. When two impurities are introduced, impurity–impurity correlations, for either attractive or strong repulsive couplings, induce a spectral shift of the resonances with respect to the single impurity. For a heavy impurity, the polaronic peak is accompanied by a series of equidistant side-band resonances, related to interference of the impurity spin dynamics and the sound waves of the bath. In all cases, we enter the diabatic transfer regime for an increasing bare Rabi frequency of the RF field with a Lorentzian spectral shape featuring a single polaronic resonance. The findings in this work on the effects of external trap, RF pulse and impurity–impurity interaction should have implications for the new generations of cold-atom experiments.

On-Farm Assessment of AquaSpy Soil Moisture Sensors for Irrigation Scheduling

The aim of this study was to compare a commercially-available radio-frequency (RF) spectroscopy soil moisture sensor with an array of calibrated research-grade soil water reflectometers in a no-till irrigated corn field from June to September 2020. The RF probe consisted of 12 sensors spaced at 4-inch intervals across 48 inches in length, while the array of soil water reflectometers consisted of four sensors deployed along the soil profile at 4, 12, 20, and 28 in. depth. Soil moisture sensors were installed at approximately 30-ft apart in two different regions within the same field characterized by contrasting soil textural classes. Hourly soil moisture and soil temperature were collected by both sensors and compared across the study period. The RF probe closely followed the soil moisture dynamics captured by the research-grade sensors. Preliminary results reveal that the tested RF sensor is useful for irrigation scheduling based on relative soil moisture values. Field-specific calibrations are required to translate the relative soil moisture measurements of the RF sensor into soil water storage in terms of volumetric water content or inches of water in the soil profile.

Core polarizability of rubidium using spectroscopy of the ng to nh, ni Rydberg transitions

We present a precise measurement of the rubidium ionic core polarizability. The results can be useful for interpreting experiments such as parity violation or black-body radiation shifts in atomic clocks since the ionic core electrons contribute significantly to the total electrical polarizability of rubidium. We report a dipole polarizability $\alpha_d$ = $9.116 \pm 0.009$ $a_0^3$ and quadrupole polarizability $\alpha_q$ = $38.4 \pm 0.6$ $a_{0}^{5}$ derived from microwave and radio-frequency spectroscopy measurements of Rydberg states with large angular momentum. By using a relatively low principal quantum number ($17 \leq n \leq 19$) and high angular momentum ($4 \leq \ell \leq 6$), systematic effects are reduced compared to previous experiments. We develop an empirical approach to account for non-adiabatic corrections to the polarizability model. The corrections have less than a 1\% effect on $\alpha_d$ but almost double $\alpha_q$ from its adiabatic value, bringing it into much better agreement with theoretical values.