The control of low-energy electrons by carrier-envelope-phase-stable near-single-cycle THz pulses is demonstrated. A femtosecond laser pulse is used to create a temporally localized wave packet through multiphoton absorption at a well defined phase of a synchronized THz field. By recording the photoelectron momentum distributions as a function of the time delay, we observe signatures of various regimes of dynamics, ranging from recollision-free acceleration to coherent electron-ion scattering induced by the THz field. The measurements are confirmed by three-dimensional time-dependent Schrödinger equation simulations. A classical trajectory model allows us to identify scattering phenomena analogous to strong-field photoelectron holography and high-order above-threshold ionization.

Advances of high intensity lasers have opened up the field of strong field physics and led to a broad range of technological applications. Recent x-ray laser sources and optics development makes it possible to obtain extremely high intensity and brightness at x-ray wavelengths. In this Letter, we present a system design that implements chirped pulse amplification for hard x-ray free electron lasers. Numerical modeling with realistic experimental parameters shows that near-transform-limit single-femtosecond hard x-ray laser pulses with peak power exceeding 1 TW and brightness exceeding $4\times {10}^{35}{\mathrm{s}}^{-1}{\mathrm{mm}}^{-2}{\mathrm{mrad}}^{-2}0.1\%{\mathrm{bandwdith}}^{-1}$ can be consistently generated. Realization of such beam qualities is essential for establishing systematic and quantitative understanding of strong field x-ray physics and nonlinear x-ray optics phenomena.

High quality nanomechanical oscillators are promising platforms for quantum entanglement and quantum technology with phonons. Realizing coherent transfer of phonons between distant oscillators is a key challenge in phononic quantum information processing. Here, we report on the realization of robust unidirectional adiabatic pumping of phonons in a parametrically coupled nanomechanical system engineered as a one-dimensional phononic topological insulator. By exploiting three nearly degenerate local modes—two edge states and an interface state between them—and the dynamic modulation of their mutual couplings, we achieve nonreciprocal adiabatic transfer of phononic excitations from one edge to the other with near unit fidelity. We further demonstrate the robustness of such adiabatic transfer of phonons in the presence of various noises in the control signals. Our experiment paves the way toward nonreciprocal phonon dynamics via adiabatic pumping and is valuable for phononic quantum information processing.

Materials hosting kagome lattices have drawn interest for the diverse magnetic and electronic states generated by geometric frustration. In the $A{\mathrm{V}}_3{\mathrm{Sb}}_5$ compounds ($A=\mathrm{K}$, Rb, Cs), stacked vanadium kagome layers give rise to unusual charge density waves (CDW) and superconductivity. Here we report single-crystal growth and characterization of ${\mathrm{ScV}}_6{\mathrm{Sn}}_6$, a hexagonal ${\mathrm{HfFe}}_6{\mathrm{Ge}}_6$-type compound that shares this structural motif. We identify a first-order phase transition at 92 K. Single crystal x-ray and neutron diffraction reveal a charge density wave modulation of the atomic lattice below this temperature. This is a distinctly different structural mode than that observed in the $A{\mathrm{V}}_3{\mathrm{Sb}}_5$ compounds, but both modes have been anticipated in kagome metals. The diverse ${\mathrm{HfFe}}_6{\mathrm{Ge}}_6$ family offers more opportunities to tune ${\mathrm{ScV}}_6{\mathrm{Sn}}_6$ and explore density wave order in kagome lattice materials.

Near-band-gap photoemission spectroscopy experiments were performed on $p\text{−}\mathrm{GaN}$ and $p\text{−}\mathrm{InGaN}/\mathrm{GaN}$ photocathodes activated to negative electron affinity. The photoemission quantum yield of the InGaN samples with more than 5% of indium drops by more than 1 order of magnitude when the temperature is decreased while it remains constant for lower indium content. This drop is attributed to a freezing of photoelectron transport in $p$-InGaN due to electron localization in the fluctuating potential induced by the alloy disorder. This interpretation is supported by the disappearance at low temperature of the peak in the photoemission spectrum that corresponds to the contribution of the photoelectrons relaxed at the bottom of the InGaN conduction band.

In active nematic liquid crystals, activity is able to drive chaotic spatiotemporal flows referred to as active turbulence. Active turbulence has been characterized through theoretical and experimental work as a low Reynolds number phenomenon. We show that, in two dimensions, the active forcing alone is able to trigger hydrodynamic turbulence leading to the coexistence of active and inertial turbulence. This type of flow develops for sufficiently active and extensile flow-aligning nematics. We observe that the combined effect of an extensile nematic and large values of the flow-aligning parameter leads to a broadening of the elastic energy spectrum that promotes a growth of kinetic energy able to trigger an inverse energy cascade.

The thermodynamic uncertainty relation (TUR) has been well studied for systems with few degrees of freedom. While, in principle, the TUR holds for more complex systems with many interacting degrees of freedom as well, little is known so far about its behavior in such systems. We analyze the TUR in the thermodynamic limit for mixtures of driven particles with short-range interactions. Our main result is an explicit expression for the optimal estimate of the total entropy production in terms of single-particle currents and correlations between two-particle currents. Quantitative results for various versions of a driven lattice gas demonstrate the practical implementation of this approach.

We consider graviton scattering in maximal supergravity on anti–de Sitter space (AdS) in $d+1$ dimensions for $d=3$, 4, and 6 with no extra compact spacetime factor. Holography suggests that this theory is dual to an exotic maximally supersymmetric conformal field theory (CFT) in $d$ dimensions whose only light single trace operator is the stress tensor. This contrasts with more standard cases like type IIB string theory on ${\mathrm{AdS}}_5\times S^5$ dual to $\mathcal{N}=4$ super-Yang-Mills, where the CFT has light single trace operators for each Kaluza-Klein mode on $S^5$. We compute the one-loop correction to the pure ${\mathrm{AdS}}_{d+1}$ theory in a small Planck length expansion, which is dual to the large central charge expansion in the CFT. We find that this correction saturates the most general nonperturbative conformal bootstrap bounds on this correlator in the large central charge regime for $d=3$, 4, 6, while the one-loop correction to CFTs with string and M-theory duals all lie inside the allowed region.

The 96.4 day exposure of a 3 kg ultralow noise germanium detector to the high flux of antineutrinos from a power nuclear reactor is described. A very strong preference ($p<1.2\times {10}^{-3}$) for the presence of a coherent elastic neutrino-nucleus scattering ($\mathrm{CE}\nu \mathrm{NS}$) component in the data is found, when compared to a background-only model. No such effect is visible in 25 days of operation during reactor outages. The best-fit $\mathrm{CE}\nu \mathrm{NS}$ signal is in good agreement with expectations based on a recent characterization of germanium response to sub-keV nuclear recoils. Deviations of order 60% from the standard model $\mathrm{CE}\nu \mathrm{NS}$ prediction can be excluded using present data. Standing uncertainties in models of germanium quenching factor, neutrino energy spectrum, and background are examined.

The cold and dense QCD equation of state at high baryon chemical potential ${\mu }_B$ involves at order ${\alpha }_s^2$ an all-loop summation of the soft mode $m_E\sim {\alpha }_s^{1/2}{\mu }_B$ contributions. Recently, the complete soft contributions at order ${\alpha }_s^3$ were calculated using the hard thermal loop formalism. By identifying massive renormalization group properties of the hard thermal loop theory, we resum to all orders ${\alpha }_s^p$, $p\ge 3$ the leading and next-to-leading logarithmic soft contributions. We obtain compact analytical expressions that show visible deviations from the state-of-the art results, and noticeably reduce residual scale dependence. Our results should help to reduce uncertainties in extending the equation of state in the intermediate ${\mu }_B$ regime, relevant in particular for the phenomenology of neutron stars.

The development of high-resolution, large-baseline optical interferometers would revolutionize astronomical imaging. However, classical techniques are hindered by physical limitations including loss, noise, and the fact that the received light is generally quantum in nature. We show how to overcome these issues using quantum communication techniques. We present a general framework for using quantum error correction codes for protecting and imaging starlight received at distant telescope sites. In our scheme, the quantum state of light is coherently captured into a nonradiative atomic state via stimulated Raman adiabatic passage, which is then imprinted into a quantum error correction code. The code protects the signal during subsequent potentially noisy operations necessary to extract the image parameters. We show that even a small quantum error correction code can offer significant protection against noise. For large codes, we find noise thresholds below which the information can be preserved. Our scheme represents an application for near-term quantum devices that can increase imaging resolution beyond what is feasible using classical techniques.

Some quantum critical states cannot be smoothly deformed into each other without either crossing some multicritical points or explicitly breaking certain symmetries even if they belong to the same universality class. This brings up the notion of “symmetry-enriched” quantum criticality. While recent works in the literature focused on critical states with robust degenerate edge modes, we propose that the conformal boundary condition (B.C.) is a more generic characteristic of such quantum critical states. We show that in two families of quantum spin chains, which generalize the Ising and the three-state Potts models, the quantum critical point between a symmetry-protected topological phase and a symmetry-breaking order realizes a conformal B.C. distinct from the simple Ising and Potts chains. Furthermore, we argue that the conformal B.C. can be derived from the bulk effective field theory, which realizes a novel bulk-boundary correspondence in symmetry-enriched quantum critical states.

We show that the functional renormalization group (FRG) allows for the calculation of the probability distribution function of the sum of strongly correlated random variables. On the example of the three-dimensional Ising model at criticality and using the simplest implementation of the FRG, we compute the probability distribution functions of the order parameter or, equivalently, its logarithm, called the rate functions in large deviation theory. We compute the entire family of universal scaling functions, obtained in the limit where the system size $L$ and the correlation length of the infinite system ${\xi }_{\infty }$ diverge, with the ratio $\zeta =L/{\xi }_{\infty }$ held fixed. It compares very accurately with numerical simulations.

A reliable source of identical (indistinguishable) photons is a prerequisite for exploiting interference effects, which is a necessary component for linear optical based quantum computing, and applications thereof such as Boson sampling. Generally speaking, the degree of distinguishability will determine the efficacy of the particular approach, for example by limiting the fidelity of constructed resource states, or reducing the complexity of an optical circuits output distribution. It is therefore of great practical relevance to engineer heralded sources of highly pure and indistinguishable photons. Inspired by magic state distillation, we present a protocol using standard linear optics which can be used to increase the indistinguishability of a photon source, to arbitrary accuracy. In particular, in the asymptotic limit of small error $\epsilon$, to reduce the error to ${\epsilon }^{\prime }<\epsilon$ requires $O\mathbf{(}(\epsilon /{\epsilon }^{\prime }{)}^2\mathbf{)}$ photons. We demonstrate the scheme is robust to detection and control errors in the optical components, and discuss the effect of other error sources.

A new Fano profile of a flat line is achieved experimentally by manipulating the relative amplitude of the continuum path, when $q$ takes the pure imaginary number of $-i$ in the x-ray regime. The underlying mechanism is that the interference term in the scattering will cancel the discrete term exactly. This new Fano profile renders only an observable continuum along with an invisible response to the discrete state of atomic resonance. The results suggest not only a different strategy to invisibility studies which provides a possible tool to identify weaker structures hidden by the strong white line, but also a new scenario to enrich the manipulations of two-path interference and nonlinear Fano resonance.

We show that the ponderomotive force associated with laser speckles can scatter electrons in a laser-produced plasma in a manner similar to Coulomb scattering. Analytic expressions for the effective collision rates are given. The electron-speckle collisions become important at high laser intensity or during filamentation, affecting both long- and short-pulse laser intensity regimes. As an example, we find that the effective collision rate in the laser-overlap region of hohlraums on the National Ignition Facility is expected to exceed the Coulomb collision rate by 1 order of magnitude, leading to a fundamental change to the electron transport properties. At the high intensities characteristic of short-pulse laser-plasma interactions ($I\gtrsim {10}^{17}\mathrm{W}{\mathrm{cm}}^{-2}$), the scattering is strong enough to cause the direct absorption of laser energy, generating hot electrons with energy scaling as $E\approx 1.44{(I/{10}^{18}\mathrm{W}{\mathrm{cm}}^{-2})}^{1/2}\mathrm{MeV}$, close to experimentally observed results.

Collective motion over increasing length scales is a signature of the vitrification process of liquids. We demonstrate how distinct static and dynamic length scales govern the dynamics of vitrifying films. In contrast to a monotonically growing static correlation length, the dynamical correlation length that measures the extent of surface-dynamics acceleration into the bulk displays a striking nonmonotonic temperature evolution that is robust also against changes in detailed interatomic interaction. This nonmonotonic change defines a crossover temperature $T_{*}$ that is distinct from the critical temperature $T_c$ of mode-coupling theory. We connect this nonmonotonic change to a morphological change of cooperative rearrangement regions of fast particles, and to the point where the decoupling of fast-particle motion from the bulk relaxation is most sensitive to fluctuations. We propose a rigorous definition of this new crossover temperature $T_{*}$ within a recent extension of mode-coupling theory, the stochastic $\beta$-relaxation theory.

The relativistic Dirac equation covers the fundamentals of electronic phenomena in solids and as such it effectively describes the electronic states of the topological insulators like ${\mathrm{Bi}}_2{\mathrm{Se}}_3$ and ${\mathrm{Bi}}_2{\mathrm{Te}}_3$. Topological insulators feature gapless surface states and, moreover, magnetic doping and resultant ferromagnetic ordering break time-reversal symmetry to realize quantum anomalous Hall and Chern insulators. Here, we focus on the bulk and investigate the mutual coupling of electronic and magnetic properties of Dirac electrons. Without carrier doping, spiral magnetic orders cause a ferroelectric polarization through the spin-orbit coupling. In a doped metallic state, the anisotropic magnetoresistance arises without uniform magnetization. We find that electric current induces uniform magnetization and conversely an oscillating magnetic order induces electric current. Our model provides a coherent and unified description of all those phenomena. The mutual control of electric and magnetic properties demonstrates implementations of antiferromagnetic spintronics. We also discuss the stoichiometric magnetic topological insulator ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$.