Quantum state transfer from flying photons to stationary matter qubits is an important element in the realization of quantum networks. Self-assembled semiconductor quantum dots provide a promising solid-state platform hosting both single photon and spin, with an inherent light-matter interface. Here, we develop a method to coherently and actively control the single-photon frequency bins in superposition using electro-optic modulators, and measure the spin-photon entanglement with a fidelity of $0.796\pm 0.020$. Further, by Greenberger-Horne-Zeilinger-type state projection on the frequency, path, and polarization degrees of freedom of a single photon, we demonstrate quantum state transfer from a single photon to a single electron spin confined in an InGaAs quantum dot, separated by 5 m. The quantum state mapping from the photon’s polarization to the electron’s spin is demonstrated along three different axes on the Bloch sphere, with an average fidelity of 78.5%.

Quantum memories matched to single photon sources will form an important cornerstone of future quantum network technology. We demonstrate such a memory in warm Rb vapor with on-demand storage and retrieval, based on electromagnetically induced transparency. With an acceptance bandwidth of $\delta f=0.66\mathrm{GHz}$, the memory is suitable for single photons emitted by semiconductor quantum dots. In this regime, vapor cell memories offer an excellent compromise between storage efficiency, storage time, noise level, and experimental complexity, and atomic collisions have negligible influence on the optical coherences. Operation of the memory is demonstrated using attenuated laser pulses on the single photon level. For a 50 ns storage time, we measure ${\eta }_{\mathrm{e}2\mathrm{e}}^{50\mathrm{ns}}=3.4(3)\%$ end-to-end efficiency of the fiber-coupled memory, with a total intrinsic efficiency ${\eta }_{\mathrm{int}}=17(3)\%$. Straightforward technological improvements can boost the end-to-end-efficiency to ${\eta }_{\mathrm{e}2\mathrm{e}}\approx 35\%$; beyond that, increasing the optical depth and exploiting the Zeeman substructure of the atoms will allow such a memory to approach near unity efficiency. In the present memory, the unconditional read-out noise level of $9\times {10}^{-3}$ photons is dominated by atomic fluorescence, and for input pulses containing on average ${\mu }_1=0.27(4)$ photons, the signal to noise level would be unity.

We consider a one-dimensional classical Coulomb gas of $N$-like charges in a harmonic potential—also known as the one-dimensional one-component plasma. We compute, analytically, the probability distribution of the position $x_{\max }$ of the rightmost charge in the limit of large $N$. We show that the typical fluctuations of $x_{\max }$ around its mean are described by a nontrivial scaling function, with asymmetric tails. This distribution is different from the Tracy-Widom distribution of $x_{\max }$ for Dyson’s log gas. We also compute the large deviation functions of $x_{\max }$ explicitly and show that the system exhibits a third-order phase transition, as in the log gas. Our theoretical predictions are verified numerically.

In this Letter, we present a measurement of the phase-space density distribution (PSDD) of ultracold ${}^{87}\mathrm{Rb}$ atoms performing 1D anomalous diffusion. The PSDD is imaged using a direct tomographic method based on Raman velocity selection. It reveals that the position-velocity correlation function $C_{xv}(t)$ builds up on a time scale related to the initial conditions of the ensemble and then decays asymptotically as a power law. We show that the decay follows a simple scaling theory involving the power-law asymptotic dynamics of position and velocity. The generality of this scaling theory is confirmed using Monte Carlo simulations of two distinct models of anomalous diffusion.

The first observation of the decays ${\mathrm{\Lambda }}_b^0\to {\chi }_{c1}p{K}^{-}$ and ${\mathrm{\Lambda }}_b^0\to {\chi }_{c2}p{K}^{-}$ is reported using a data sample corresponding to an integrated luminosity of $3.0{\mathrm{fb}}^{-1}$, collected by the LHCb experiment in $pp$ collisions at center-of-mass energies of 7 and 8 TeV. The following ratios of branching fractions are measured: $$\begin{gathered} \frac{\mathcal{B}({\mathrm{\Lambda }}_b^0\to {\chi }_{c1}p{K}^{-})}{\mathcal{B}({\mathrm{\Lambda }}_b^0\to J/\psi p{K}^{-})}=0.242\pm 0.014\pm 0.013\pm 0.009, \\ \frac{\mathcal{B}({\mathrm{\Lambda }}_b^0\to {\chi }_{c2}p{K}^{-})}{\mathcal{B}({\mathrm{\Lambda }}_b^0\to J/\psi p{K}^{-})}=0.248\pm 0.020\pm 0.014\pm 0.009, \\ \frac{\mathcal{B}({\mathrm{\Lambda }}_b^0\to {\chi }_{c2}p{K}^{-})}{\mathcal{B}({\mathrm{\Lambda }}_b^0\to {\chi }_{c1}p{K}^{-})}=1.02\pm 0.10\pm 0.02\pm 0.05, \end{gathered}$$where the first uncertainty is statistical, the second systematic, and the third due to the uncertainty on the branching fractions of the ${\chi }_{c1}\to J/\psi \gamma$ and ${\chi }_{c2}\to J/\psi \gamma$ decays. Using both decay modes, the mass of the ${\mathrm{\Lambda }}_b^0$ baryon is also measured to be $m_{{\mathrm{\Lambda }}_b^0}=5619.44\pm 0.28\pm 0.26\mathrm{MeV}/c^2$, where the first and second uncertainties are statistical and systematic, respectively.

We put forward a new ab initio approach that seamlessly bridges the structure, clustering, and reactions aspects of the nuclear quantum many-body problem. The configuration interaction technique combined with the resonating group method based on a harmonic oscillator basis allows us to treat the reaction and multiclustering dynamics in a translationally invariant way and preserve the Pauli principle. Our presentation includes studies of ${}^{8,10}\mathrm{Be}$ and an exploration of $3\alpha$ clustering in ${}^{12}\mathrm{C}$.

We present an in-depth many-body investigation of the so-called mesoscopic molecular ions that can buildup when an ion is immersed into an atomic Bose-Einstein condensate in one dimension. To this end, we employ the multilayer multiconfiguration time-dependent Hartree method for mixtures of ultracold bosonic species for solving the underlying many-body Schrödinger equation. This enables us to unravel the actual structure of such massive charged molecules from a microscopic perspective. Laying out their phase diagram with respect to atom number and interatomic interaction strength, we determine the maximal number of atoms bound to the ion and reveal spatial densities and molecular properties. Interestingly, we observe a strong interaction-induced localization, especially for the ion, that we explain by the generation of a large effective mass, similarly to ions in liquid Helium. Finally, we predict the dynamical response of the ion to small perturbations. Our results provide clear evidence for the importance of quantum correlations, as we demonstrate by benchmarking them with wave function ansatz classes employed in the literature.

High harmonics driven by two-color counterrotating circularly polarized laser fields are a unique source of bright, circularly polarized, extreme ultraviolet, and soft x-ray beams, where the individual harmonics themselves are completely circularly polarized. Here, we demonstrate the ability to preferentially select either the right or left circularly polarized harmonics simply by adjusting the relative intensity ratio of the bichromatic circularly polarized driving laser field. In the frequency domain, this significantly enhances the harmonic orders that rotate in the same direction as the higher-intensity driving laser. In the time domain, this helicity-dependent enhancement corresponds to control over the polarization of the resulting attosecond waveforms. This helicity control enables the generation of circularly polarized high harmonics with a user-defined polarization of the underlying attosecond bursts. In the future, this technique should allow for the production of bright highly elliptical harmonic supercontinua as well as the generation of isolated elliptically polarized attosecond pulses.

We demonstrate the coherent coupling and the resulting transfer of phase information between microwave and optical fields in a single nitrogen vacancy center in diamond. The relative phase of two microwave fields is encoded in a coherent superposition spin state. This phase information is then retrieved with a pair of optical fields. A related process is also used for the transfer of phase information from optical to microwave fields. These studies show the essential role of dark states, including optical pumping into the dark states, in the coherent microwave-optical coupling and open the door to the full quantum state transfer between microwave and optical fields in a solid-state spin ensemble.

We compute the orbital angular momentum $L_z$ of an $s$-wave paired superfluid in the presence of an axisymmetric multiply quantized vortex. For vortices with a winding number $|k|>1$, we find that in the weak-pairing BCS regime, $L_z$ is significantly reduced from its value $\hslash Nk/2$ in the Bose-Einstein condensation (BEC) regime, where $N$ is the total number of fermions. This deviation results from the presence of unpaired fermions in the BCS ground state, which arise as a consequence of spectral flow along the vortex subgap states. We support our results analytically and numerically by solving the Bogoliubov–de Gennes equations within the weak-pairing BCS regime.

Recent observation of $\sim 10$ times higher critical temperature in a FeSe monolayer compared with its bulk phase has drawn a great deal of attention because the electronic structure in the monolayer phase appears to be different than bulk FeSe. Using a combination of density functional theory and dynamical mean field theory, we find electronic correlations have important effects on the predicted atomic-scale geometry and the electronic structure of the monolayer FeSe on ${\mathrm{SrTiO}}_3$. The electronic correlations are dominantly controlled by the Se-Fe-Se angle either in the bulk phase or the monolayer phase. But the angle sensitivity increases and the orbital differentiation decreases in the monolayer phase compared to the bulk phase. The correlations are more dependent on Hund’s $J$ than Hubbard $U$. The observed orbital selective incoherence to coherence crossover with temperature confirms the Hund’s metallic nature of the monolayer FeSe. We also find electron doping by oxygen vacancies in ${\mathrm{SrTiO}}_3$ increases the correlation strength, especially in the $d_{xy}$ orbital by reducing the Se-Fe-Se angle.

We present and analyze Raman spectra of the Mott insulator ${\mathrm{Ca}}_2{\mathrm{RuO}}_4$, whose quasi-two-dimensional antiferromagnetic order has been described as a condensate of low-lying spin-orbit excitons with angular momentum $J_{\text{eff}}=1$. In the $A_g$ polarization geometry, the amplitude (Higgs) mode of the spin-orbit condensate is directly probed in the scalar channel, thus avoiding infrared-singular magnon contributions. In the $B_{1g}$ geometry, we observe a single-magnon peak as well as two-magnon and two-Higgs excitations. Model calculations using exact diagonalization quantitatively agree with the observations. Together with recent neutron scattering data, our study provides strong evidence for excitonic magnetism in ${\mathrm{Ca}}_2{\mathrm{RuO}}_4$ and points out new perspectives for research on the Higgs mode in two dimensions.

We demonstrate that multiply coupled spinor polariton condensates can be optically tuned through a sequence of spin-ordered phases by changing the coupling strength between nearest neighbors. For closed four-condensate chains these phases span from ferromagnetic (FM) to antiferromagnetic (AFM), separated by an unexpected crossover phase. This crossover phase is composed of alternating FM-AFM bonds. For larger eight-condensate chains, we show the critical role of spatial inhomogeneities and demonstrate a scheme to overcome them and prepare any desired spin state. Our observations thus demonstrate a fully controllable nonequilibrium spin lattice.

We use a first-principles density functional theory approach to calculate the shift current and linear absorption of uniformly illuminated single-layer Ge and Sn monochalcogenides. We predict strong absorption in the visible spectrum and a large effective three-dimensional shift current ($\sim 100\mu \mathrm{A}/{\mathrm{V}}^2$), larger than has been previously observed in other polar systems. Moreover, we show that the integral of the shift-current tensor is correlated to the large spontaneous effective three-dimensional electric polarization ($\sim 1.9\mathrm{C}/{\mathrm{m}}^2$). Our calculations indicate that the shift current will be largest in the visible spectrum, suggesting that these monochalcogenides may be promising for polar optoelectronic devices. A Rice-Mele tight-binding model is used to rationalize the shift-current response for these systems, and its dependence on polarization, in general terms with implications for other polar materials

We present a study of the hydrodynamics of an active particle—a model squirmer—in an environment with a broken rotational symmetry: a nematic liquid crystal. By combining simulations with analytic calculations, we show that the hydrodynamic coupling between the squirmer flow field and liquid crystalline director can lead to reorientation of the swimmers. The preferred orientation depends on the exact details of the squirmer flow field. In a steady state, pushers are shown to swim parallel with the nematic director while pullers swim perpendicular to the nematic director. This behavior arises solely from hydrodynamic coupling between the squirmer flow field and anisotropic viscosities of the host fluid. Our results suggest that an anisotropic swimming medium can be used to characterize and guide spherical microswimmers in the bulk.

We study triggering processes in triaxial compression experiments under a constant displacement rate on sandstone and granite samples using spatially located acoustic emission events and their focal mechanisms. We present strong evidence that event-event triggering plays an important role in the presence of large-scale or macrocopic imperfections, while such triggering is basically absent if no significant imperfections are present. In the former case, we recover all established empirical relations of aftershock seismicity including the Gutenberg-Richter relation, a modified version of the Omori-Utsu relation and the productivity relation—despite the fact that the activity is dominated by compaction-type events and triggering cascades have a swarmlike topology. For the Gutenberg-Richter relations, we find that the $b$ value is smaller for triggered events compared to background events. Moreover, we show that triggered acoustic emission events have a focal mechanism much more similar to their associated trigger than expected by chance.