Recent years have seen extraordinary progress in creating quantum states of mechanical oscillators, leading to great interest in potential applications for such systems in both fundamental as well as applied quantum science. One example is the use of these devices as transducers between otherwise disparate quantum systems. In this regard, a promising approach is to build integrated piezoelectric optomechanical devices that are then coupled to microwave circuits. Optical absorption, low quality factors, and other challenges have up to now prevented operation in the quantum regime, however. Here, we design and characterize such a piezoelectric optomechanical device fabricated from gallium phosphide in which a 2.9 GHz mechanical mode is coupled to a high quality factor optical resonator in the telecom band. The large electronic band gap and the resulting low optical absorption of this new material, on par with devices fabricated from silicon, allows us to demonstrate quantum behavior of the structure. This not only opens the way for realizing noise-free quantum transduction between microwaves and optics, but in principle also from various color centers with optical transitions in the near visible to the telecom band.

Motivated by recent interest in photon and electron vortex beams, we propose the construction of a relativistic anyon beam. Following Jackiw and Nair [R. Jackiw and V. P. Nair, Phys. Rev. D 43, 1933 (1991).] we derive an explicit form of the relativistic plane wave solution of a single anyon. Subsequently we construct the planar anyon beam by superposing these solutions. Explicit expressions for the conserved anyon current are derived. Finally, we provide expressions for the anyon beam current using the superposed waves and discuss its properties. We also comment on the possibility of laboratory construction of an anyon beam.

Neutron spectra from secondary ${}^3\mathrm{H}(d,n)\alpha$ reactions produced by an implosion of a deuterium-gas capsule at the National Ignition Facility have been measured with order-of-magnitude improvements in statistics and resolution over past experiments. These new data and their sensitivity to the energy loss of fast tritons emitted from thermal ${}^2\mathrm{H}(d,p){}^3\mathrm{H}$ reactions enable the first statistically significant investigation of charged-particle stopping via the emitted neutron spectrum. Radiation-hydrodynamic simulations, constrained to match a number of observables from the implosion, were used to predict the neutron spectra while employing two different energy loss models. This analysis represents the first test of stopping models under inertial confinement fusion conditions, covering plasma temperatures of $k_{B}T\approx 1–4\mathrm{keV}$ and particle densities of $n\approx (12–2)\times {10}^{24}{\mathrm{cm}}^{-3}$. Under these conditions, we find significant deviations of our data from a theory employing classical collisions whereas the theory including quantum diffraction agrees with our data.

We show, theoretically, that a heterostructure of monolayer ${\mathrm{FeTe}}_{1-x}{\mathrm{Se}}_x$—a superconducting quantum spin Hall material—with a monolayer of FeTe—a bicollinear antiferromagnet—realizes a higher order topological superconductor phase characterized by emergent Majorana zero modes pinned to the sample corners. We provide a minimal effective model for this system, analyze the origin of higher order topology, and fully characterize the topological phase diagram. Despite the conventional $s$-wave pairing, we find a rather surprising emergence of a novel topological nodal superconductor in the phase diagram. Featured by edge-dependent Majorana flat bands, the topological nodal phase is protected by an antiferromagnetic chiral symmetry. We also discuss the experimental feasibility, the estimation of realistic model parameters, and the robustness of the Majorana corner modes against magnetic and potential disorder. Our work provides a new experimentally feasible high-temperature platform for both higher order topology and non-Abelian Majorana physics.

We discover an excited bound three-particle state, the $2s$ trion, appearing energetically below the $2s$ exciton in monolayer ${\mathrm{WS}}_2$, using absorption spectroscopy and ab initio GW and Bethe-Salpeter equation calculations. The measured binding energy of the $2s$ trion (22 meV) is smaller compared to the $1s$ intravalley and intervalley trions (37 and 31 meV). With increasing temperature, the $1s$ and $2s$ trions transfer their oscillator strengths to the respective neutral excitons, establishing an optical fingerprint of trion-exciton resonance pairs. Our discovery underlines the importance of trions for the entire excitation spectrum of two-dimensional semiconductors.

Unusual structures and dynamic properties found in polymer nanocomposites (PNCs) are often attributed to immobilized (adsorbed) polymers at nanoparticle-polymer interfaces, which are responsible for reducing the intrinsic incompatibility between nanoparticles and polymers in PNCs. Although tremendous effort has been made to characterize the presence of immobilized polymers, a systematic understanding of the structure and dynamics under different processing conditions is still lacking. Here, we report that the initial dispersing solvent, which is not present after producing PNCs, drives these nonequilibrium effects on polymer chain dynamics at interfaces. Employing extensive small-angle scattering, proton NMR spectroscopy, and rheometry experiments, we found that the thickness of the immobilized layer can be dependent on the initial solvent, changing the structure and the properties of the PNC significantly. In addition, we show that the outcome of the initial solvent effect becomes more effective at particle volume fractions where the immobile layers begin to interact.

Inserting a rigid object into a soft elastic tube produces conformal contact between the two, resulting in contact lines. The curvature of the tube walls near these contact lines is often large and is typically regularized by the finite bending rigidity of the tube. Here, it is demonstrated using experiments and a Föppl–von Kármán–like theory that a second, independent, mechanism of curvature regularization occurs when the tube is axially stretched. In contrast with the effects of finite bending rigidity, the radius of curvature obtained increases with the applied stretching force and decreases with sheet thickness. The dependence of the curvature on a suitably rescaled stretching force is found to be universal, independent of the shape of the intruder, and results from an interplay between the longitudinal stresses due to the applied stretch and hoop stresses characteristic of curved geometry. These results suggest that curvature measurements can be used to infer the mechanical properties of stretched tubular structures.

We report on the theoretical model and experimental results of the experiment made in a limit of absolute zero temperature ($\sim 600\mu \mathrm{K}$) studying the spin wave analog of black- and white-hole horizons using spin (magnonic) superfluidity in superfluid ${}^3\mathrm{He}\text{−}B$. As an experimental tool simulating the properties of the black- and white-hole horizons, we used the spin-precession waves propagating on the background of the spin supercurrents between two Bose-Einstein condensates of magnons in the form of homogeneously precessing domains. We provide experimental evidence of the white hole formation for spin precession waves in this system, together with the observation of an amplification effect. Moreover, the estimated temperature of the spontaneous Hawking radiation in this system is about 4 orders of magnitude lower than the system’s background temperature which makes it a promising tool for studying the effect of spontaneous Hawking radiation.

We construct a theory in which the solution to the strong $CP$ problem is an emergent property of the background of the dark matter in the Universe. The role of the axion degree of freedom is played by multibody collective excitations similar to spin waves in the medium of the dark matter of the Galactic halo. The dark matter is a vector particle whose low energy interactions with the standard model take the form of its spin density coupled to $G\tilde{G}$, which induces a potential on the average spin density inducing it to compensate $\overline{\theta }$, effectively removing $CP$ violation in the strong sector in regions of the Universe with sufficient dark matter density. We discuss the viable parameter space, finding that light dark matter masses within a few orders of magnitude of the fuzzy limit are preferred, and discuss the associated signals with this type of solution to the strong $CP$ problem.

The Polarized Atomic Hydrogen Gas Jet Target polarimeter is employed by the Relativistic Heavy Ion Collider (RHIC) to measure the absolute polarization of each colliding proton beam. Polarimeter detectors and data acquisition were upgraded in 2015 to increase solid angle, energy range, and energy resolution. These upgrades and advanced systematic error analysis along with improved beam intensity and polarization in RHIC runs 2015 ($E_{\mathrm{beam}}=100\mathrm{GeV}$) and 2017 (255 GeV) allowed us to greatly reduce the statistical and systematic uncertainties for elastic spin asymmetries, $A_{\mathrm{N}}(t)$ and $A_{\mathrm{NN}}(t)$, in the Coulomb-nuclear interference momentum transfer range $0.0013<-t<0.018{\mathrm{GeV}}^2$. For the first time hadronic single spin-flip $r_5$ and double spin-flip $r_2$ amplitude parameters were reliably isolated at these energies and momentum transfers. Measurements at two beam energies enable a separation of Pomeron and Regge pole contributions to $r_5(s)$ and $r_2(s)$, indicating that the spin component may persist at high energies.

We report the first measurement of rapidity-odd directed flow ($v_1$) for $D^0$ and $\overline{D^0}$ mesons at midrapidity ($|y|<0.8$) in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=200\mathrm{GeV}$ using the STAR detector at the Relativistic Heavy Ion Collider. In 10–80% $\mathrm{Au}+\mathrm{Au}$ collisions, the slope of the $v_1$ rapidity dependence ($d{v}_1/dy$), averaged over $D^0$ and $\overline{D^0}$ mesons, is $-0.080\pm 0.017(\text{stat})\pm 0.016(\text{syst})$ for transverse momentum $p_T$ above $1.5\mathrm{GeV}/c$. The absolute value of $D^0$ meson $d{v}_1/dy$ is about 25 times larger than that for charged kaons, with $3.4\sigma$ significance. These data give a unique insight into the initial tilt of the produced matter, and offer constraints on the geometric and transport parameters of the hot QCD medium created in relativistic heavy-ion collisions.

Chu’s limit determines the minimum radiation quality factor $Q$ of an electrically small resonator, and hence its maximum operational bandwidth, which is inversely proportional to its volume. This bound imposes severe restrictions in several areas of technology, from wireless communications to nanophotonics and metamaterials. We show that a suitably tailored temporal modulation of the matching network, combined with proper detuning of the feeding impedance, can overcome this limit and enable radiation over broader bandwidths, which scale as $1/\sqrt{Q}$, ensuring at the same time stability. Our findings open opportunities for communication systems, nanophotonics, and sensor technology.

The iron-based superconductor FeSe offers a unique possibility to study the interplay of superconductivity with purely nematic as well magnetic-nematic order by pressure ($p$) tuning. By measuring specific heat under $p$ up to 2.36 GPa, we study the multiple phases in FeSe using a thermodynamic probe. We conclude that superconductivity is bulk across the entire $p$ range and competes with magnetism. In addition, whenever magnetism is present, fluctuations exist over a wide temperature range above both the bulk superconducting and the magnetic transitions. Whereas the magnetic fluctuations are likely temporal, the superconducting fluctuations may be either temporal or spatial. These observations highlight similarities between FeSe and underdoped cuprate superconductors.

Coherent generation of indistinguishable single photons is crucial for many quantum communication and processing protocols. Solid-state realizations of two-level atomic transitions or three-level spin-$\mathrm{\Lambda }$ systems offer significant advantages over their atomic counterparts for this purpose, albeit decoherence can arise due to environmental couplings. One popular approach to mitigate dephasing is to operate in the weak-excitation limit, where the excited-state population is minimal and coherently scattered photons dominate over incoherent emission. Here we probe the coherence of photons produced using two-level and spin-$\mathrm{\Lambda }$ solid-state systems. We observe that the coupling of the atomiclike transitions to the vibronic transitions of the crystal lattice is independent of the driving strength, even for detuned excitation using the spin-$\mathrm{\Lambda }$ configuration. We apply a polaron master equation to capture the non-Markovian dynamics of the vibrational manifolds. These results provide insight into the fundamental limitations to photon coherence from solid-state quantum emitters.

Coherent scattering of light by a single quantum emitter is a fundamental process at the heart of many proposed quantum technologies. Unlike atomic systems, solid-state emitters couple to their host lattice by phonons. Using a quantum dot in an optical nanocavity, we resolve these interactions in both time and frequency domains, going beyond the atomic picture to develop a comprehensive model of light scattering from solid-state emitters. We find that even in the presence of a low-$Q$ cavity with high Purcell enhancement, phonon coupling leads to a sideband that is completely insensitive to excitation conditions and to a nonmonotonic relationship between laser detuning and coherent fraction, both of which are major deviations from atomlike behavior.

Quantum chaotic interacting $N$-particle systems are assumed to show fast and irreversible spreading of quantum information on short (Ehrenfest) time scales $\sim \log N$. Here, we show that, near criticality, certain many-body systems exhibit fast initial scrambling, followed subsequently by oscillatory behavior between reentrant localization and delocalization of information in Hilbert space. We consider both integrable and nonintegrable quantum critical bosonic systems with attractive contact interaction that exhibit locally unstable dynamics in the corresponding many-body phase space of the large-$N$ limit. Semiclassical quantization of the latter accounts for many-body correlations in excellent agreement with simulations. Most notably, it predicts an asymptotically constant local level spacing $\hslash /\tau$, again given by $\tau \sim \log N$. This unique timescale governs the long-time behavior of out-of-time-order correlators that feature quasiperiodic recurrences indicating reversibility.

We report results on the searches of weakly interacting massive particles (WIMPs) with sub-GeV masses ($m_{\chi }$) via WIMP-nucleus spin-independent scattering with Migdal effect incorporated. Analysis on time-integrated (TI) and annual modulation (AM) effects on CDEX-1B data are performed, with 737.1 kg day exposure and 160 eVee threshold for TI analysis, and 1107.5 kg day exposure and 250 eVee threshold for AM analysis. The sensitive windows in $m_{\chi }$ are expanded by an order of magnitude to lower DM masses with Migdal effect incorporated. New limits on ${\sigma }_{\chi N}^{\mathrm{SI}}$ at 90% confidence level are derived as $2\times {10}^{-32}\sim 7\times {10}^{-35}{\mathrm{cm}}^2$ for TI analysis at $m_{\chi }\sim 50–180\mathrm{MeV}/c^2$, and $3\times {10}^{-32}\sim 9\times {10}^{-38}{\mathrm{cm}}^2$ for AM analysis at $m_{\chi }\sim 75\mathrm{MeV}/c^2–3.0\mathrm{GeV}/c^2$.