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1. A Mach-Zehnder Fabry-Perot hybrid fiber-optic interferometer operating at the thermal noise limit

   https://doi.org/10.1038/s41598-022-16474-y  

   Hoque, Nabil Md Rakinul ; Duan, Lingze ( July 2022 , Scientific Reports)

   A new type of interferometric fiber sensor based on a Mach-Zehnder Fabry-Perot hybrid scheme has been experimentally demonstrated. The interferometer combines the benefits of both a double-path configuration and an optical resonator, leading to record-high strain and phase resolutions limited only by the intrinsic thermal noise in optical fibers across a broad frequency range. Using only off-the-shelf components, the sensor is able to achieve noise-limited strain resolutions of 40 f$$\varepsilon $$$\epsilon$/$$\sqrt{(}Hz)$$$\sqrt{(}Hz)$at 10 Hz and 1 f$$\varepsilon $$$\epsilon$/$$\sqrt{(}Hz)$$$\sqrt{(}Hz)$at 100 kHz. With a proper scale-up, atto-strain resolutions are believed to be within reach in the ultrasonic frequency range with such interferometers.

    

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2. Rate of convergence in periodic homogenization for convex Hamilton–Jacobi equations with multiscales

   https://doi.org/10.1088/1361-6544/acf17c  

   Han, Yuxi ; Jang, Jiwoong ( August 2023 , Nonlinearity)

   We study the rate of convergence in periodic homogenization for convex Hamilton–Jacobi equations with multiscales, where the Hamiltonian$H=H(x,y,p):{\mathbb{R}}^n\times {\mathbb{T}}^n\times {\mathbb{R}}^n\to \mathbb{R}$depends on both of the spatial variable and the oscillatory variable. In particular, we show that for the Cauchy problem, the rate of convergence is$O(t\sqrt{ϵ})$by optimal control formulas, scale separations and curve cutting techniques. We also show the rate$O(\frac{\sqrt{ϵ}}{\lambda })$of homogenization for the static problem based on the same idea. Additionally, we provide examples that illustrate the rate of convergence for the Cauchy problem is optimal for$0<t<\sqrt{ϵ}$and$t\sim \sqrt{ϵ}$.

    

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3. Optomechanical lasers for inertial sensing

   https://doi.org/10.1364/JOSAA.396774  

   Wisniewski, Hayden ; Richardson, Logan ; Hines, Adam ; Laurain, Alexandre ; Guzmán, Felipe ( August 2020 , Journal of the Optical Society of America A)

   We have developed an inertially sensitive optomechanical laser by combining a vertical-external-cavity surface-emitting laser (VECSEL) with a monolithic fused silica resonator. By placing the external cavity mirror of the VECSEL onto the optomechanical resonator test mass, we create a sensor where external accelerations are directly transcribed onto the lasing frequency. We developed a proof-of-principle laboratory prototype and observe test mass oscillations at the resonance frequency of the sensor through the VECSEL lasing frequency,$4.18\pm <\#comment/>0.03\mathrm{H}\mathrm{z}$. In addition, we set up an ancillary heterodyne interferometer to track the motion of the mechanical oscillator’s test mass, observing a resonance of$4.194\pm <\#comment/>0.004\mathrm{H}\mathrm{z}$. The interferometer measurements validate the VECSEL results, confirming the feasibility of using optomechanical lasers for inertial sensing.

    

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4. A search for decays of the Higgs boson to invisible particles in events with a top-antitop quark pair or a vector boson in proton-proton collisions at $$\sqrt{s} = 13\,\text {Te}\hspace{-.08em}\text {V} $$

   https://doi.org/10.1140/epjc/s10052-023-11952-7  

   Tumasyan, A. ; Adam, W. ; Andrejkovic, J. W. ; Bergauer, T. ; Chatterjee, S. ; Damanakis, K. ; Dragicevic, M. ; Escalante Del Valle, A. ; Hussain, P. S. ; Jeitler, M. ; et al ( October 2023 , The European Physical Journal C)

   A search for decays to invisible particles of Higgs bosons produced in association with a top-antitop quark pair or a vector boson, which both decay to a fully hadronic final state, has been performed using proton-proton collision data collected at$${\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V}}$$$\sqrt{s}=13\text{Te}\text{V}$by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138$$\,\text {fb}^{-1}$$${\text{fb}}^{-1}$. The 95% confidence level upper limit set on the branching fraction of the 125$$\,\text {Ge}\hspace{-.08em}\text {V}$$$\text{Ge}\text{V}$Higgs boson to invisible particles,$${\mathcal {B}({\textrm{H}} \rightarrow \text {inv})}$$$B(\text{H}\to \text{inv})$, is 0.54 (0.39 expected), assuming standard model production cross sections. The results of this analysis are combined with previous$${\mathcal {B}({\textrm{H}} \rightarrow \text {inv})}$$$B(\text{H}\to \text{inv})$searches carried out at$${\sqrt{s}=7}$$$\sqrt{s}=7$, 8, and 13$$\,\text {Te}\hspace{-.08em}\text {V}$$$\text{Te}\text{V}$in complementary production modes. The combined upper limit at 95% confidence level on$${\mathcal {B}({\textrm{H}} \rightarrow \text {inv})}$$$B(\text{H}\to \text{inv})$is 0.15 (0.08 expected).

    

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5. Spin structure and dynamics of the topological semimetal Co3Sn2-xInxS2

   https://doi.org/10.1038/s41535-022-00523-w  

   Neubauer, Kelly J. ; Ye, Feng ; Shi, Yue ; Malinowski, Paul ; Gao, Bin ; Taddei, Keith M. ; Bourges, Philippe ; Ivanov, Alexandre ; Chu, Jiun-Haw ; Dai, Pengcheng ( December 2022 , npj Quantum Materials)

   The anomalous Hall effect (AHE), typically observed in ferromagnetic (FM) metals with broken time-reversal symmetry, depends on electronic and magnetic properties. In Co₃Sn_2-xIn_xS₂, a giant AHE has been attributed to Berry curvature associated with the FM Weyl semimetal phase, yet recent studies report complicated magnetism. We use neutron scattering to determine the spin dynamics and structures as a function ofxand provide a microscopic understanding of the AHE and magnetism interplay. Spin gap and stiffness indicate a contribution from Weyl fermions consistent with the AHE. The magnetic structure evolves fromc-axis ferromagnetism at$$x = 0$$$x=0$to a canted antiferromagnetic (AFM) structure with reducedc-axis moment and in-plane AFM order at$$x = 0.12$$$x=0.12$and further reducedc-axis FM moment at$$x = 0.3$$$x=0.3$. Since noncollinear spins can induce non-zero Berry curvature in real space acting as a fictitious magnetic field, our results revealed another AHE contribution, establishing the impact of magnetism on transport.

    

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