Power amplification and pulse compression of short-pulse laser beams by three-wave nonlinear processes in a plasma was proposed by Malkin, Shvets, and Fisch [Phys. Rev. Lett. 82, 4448 (1999)] as a potential path to exceed the limits of the highly successful technique of chirped pulse amplification [D. Strickland and G. Mourou, Opt. Commun. 56, 219 (1985)] developed three decades ago. The parametric processes considered, Raman and Brillouin scattering, are notoriously difficult to control and to predict theoretically because of the dependence on plasma properties and other nonlinear processes. Previous experiments of backward Raman and Brillouin amplifiers have fallen far short of the predictions of simulations and theory and achieved only a very small energy transfer. In this paper, laser-plasma amplification of subpicosecond pulses above the Joule level is demonstrated with a large energy transfer and a very high efficiency, up to 20%, a major milestone for this scheme to become a solution for the next generation of ultrahigh-intensity lasers. In addition, three-dimensional simulations of the amplification process quantitatively match the experimental results and demonstrate the ability of predictive simulations for the optimization of experiments. The global behavior of the amplification process is reproduced, including the evolution of the spatial profile of the amplified seed, the pulse length of the amplified seed, and the influence of parasitic spontaneous Raman and Brillouin scattering.

When an extended system is coupled at its opposite boundaries to two reservoirs at different temperatures or chemical potentials, it cannot achieve a global thermal equilibrium and is instead driven to a set of current-carrying nonequilibrium states. Despite the broad relevance of such a scenario to metallic systems, there have been limited investigations of the entanglement structure of the resulting long-time states, in part due to the fundamental difficulty in solving realistic models for disordered, interacting electrons. We investigate this problem by carefully analyzing two “toy” models for coherent quantum transport of diffusive fermions: the celebrated three-dimensional, noninteracting Anderson model, and a class of random quantum circuits acting on a chain of qubits, which exactly maps to a diffusive, interacting fermion problem. Crucially, the random circuit model can also be tuned to have no interactions between the fermions, similar to the Anderson model. We show that the long-time states of driven noninteracting fermions exhibit volume-law mutual information and entanglement, both for our random circuit model and for the nonequilibrium steady state of the Anderson model. With interactions, the random circuit model is quantum chaotic and approaches local equilibrium, with only short-range entanglement. These results provide a generic picture for the emergence of local equilibrium in current-driven, quantum-chaotic systems, and also provide examples of stable, highly entangled, many-body states out of equilibrium. We discuss experimental techniques to probe these effects in low-temperature mesoscopic wires or ultracold atomic gases.

We introduce two new complementary concepts, frictional rigidity percolation and minimal rigidity proliferation, to help identify the nature of the frictional jamming transition as well as significantly broaden the scope of rigidity percolation. To probe frictional rigidity percolation, we construct rigid clusters using a (3,3) pebble game for sliding and frictional contacts first on a honeycomb lattice with next-nearest neighbors, and second on a hierarchical lattice. For both lattices, we find a continuous rigidity transition. Our numerically obtained transition exponents for frictional rigidity percolation on the honeycomb lattice are distinct from those of central-force rigidity percolation. We propose that localized motifs, such as hinges connecting rigid clusters that are allowed only with friction, could give rise to this new frictional universality class. And yet, the distinction between the exponents characterizing the spanning rigid cluster for frictional and central-force rigidity percolation is small, motivating us to look for a limit in which they are identical, i.e., a search for mechanisms of superuniversality. To achieve this goal, we construct a minimally rigid cluster generating algorithm invoking generalized Henneberg moves, dubbed minimal rigidity proliferation. For both frictional and central-force rigidity percolation, these clusters appear to be in the same universality class as connectivity percolation, suggesting superuniversality between all three transitions for such minimally rigid clusters. These combined results allow us, for the first time in rigidity percolation, to directly compare two universality classes on the same lattice and to highlight unifying and distinguishing concepts of rigidity transitions in disordered systems.

Topological orders describe a new class of gapped quantum phases of matter at zero temperature, that has various patterns of many-body quantum entanglement. Previously, topological orders in one and two spatial dimensions have been systematically understood and classified. This paper [together with Phys. Rev. X 8, 021074 (2018)] develops a systematic and classifying understanding of topological orders in three-dimensional bosonic systems, where the number of topological types for the pointlike and stringlike excitations is assumed to be finite. Our systematic understanding comes from the unique canonical boundary for each $3+1\mathrm{D}$ topological order. We find that the pointlike and stringlike excitations on the canonical boundary are described fully by a mathematical theory—the so-called fusion 2-categories. This theory allows us to classify $3+1\mathrm{D}$ topological orders in bosonic systems in terms of a subset of fusion 2-categories. This systematic understanding further leads to a systematic understanding of $3+1\mathrm{D}$ topological orders in bosonic and fermionic systems with arbitrary finite unitary symmetry.

We provide a characterization of point defects in droplets of cholesteric liquid crystal, using a combination of experiment, simulation, and theoretical analysis. These droplets display a range of structures including realizations of defects with high topological charge and arrangements of multiple defects in “topological molecules.” We show that there are certain defects that are incompatible with a uniform sense of chiral twisting for topological reasons. Furthermore, those defects that are compatible with twist of a single handedness are shown to have the structure of the gradient field of an isolated critical point and, hence, are described by singularity theory. We show that the mathematical tools of singularity theory reproduce, with excellent agreement, the experimental observations of high charge defects and topological molecules. Our results have implications beyond liquid crystal droplets in characterizing chiral materials and their topology in general.

We study the spreading of initially local operators under unitary time evolution in a one-dimensional random quantum circuit model that is constrained to conserve a $U(1)$ charge and also the dipole moment of this charge. These constraints are motivated by the quantum dynamics of fracton phases. We discover that the charge remains localized at its initial position, providing a crisp example of a nonergodic dynamical phase of random circuit dynamics. This localization can be understood as a consequence of the return properties of low-dimensional random walks, through a mechanism reminiscent of weak localization, but insensitive to dephasing. The charge dynamics is well described by a system of coupled hydrodynamic equations, which makes several nontrivial predictions that are all in good agreement with numerics in one dimension. Importantly, these equations also predict localization in two-dimensional fractonic random circuits. We further find that the immobile fractonic charge emits nonconserved operators, whose spreading is governed by exponents that are distinct from those observed in nonfractonic circuits. These nonstandard exponents are also explained by our coupled hydrodynamic equations. Where entanglement properties are concerned, we find that fractonic operators exhibit a short time linear growth of observable entanglement with saturation to an area law, as well as a subthermal volume law for operator entanglement. The entanglement spectrum is found to follow semi-Poisson statistics, similar to eigenstates of many-body localized systems. The nonergodic phenomenology is found to persist to initial conditions containing nonzero density of dipolar or fractonic charge, including states near the sector of maximal charge. Our work implies that low-dimensional fracton systems should preserve forever a memory of their initial conditions in local observables under noisy quantum dynamics, thereby constituting ideal memories. It also implies that one- and two-dimensional fracton systems should realize true many-body localization (MBL) under Hamiltonian dynamics, even in the absence of disorder, with the obstructions to MBL in translation-invariant systems and in spatial dimensions greater than one being evaded by the nature of the mechanism responsible for localization. We also suggest a possible route to new nonergodic phases in high dimensions.

Quantum simulations with ultracold atoms typically create atomic wave functions with structures at optical length scales, where direct imaging suffers from the diffraction limit. In analogy to advances in optical microscopy for biological applications, we use a nonlinear atomic response to surpass the diffraction limit. Exploiting quantum interference, we demonstrate imaging with superresolution of $\lambda /50$ and excellent temporal resolution of 500 ns. We characterize our microscope’s performance by measuring the ensemble-averaged probability density of atoms within the unit cells of an optical lattice and observe the dynamics of atoms excited into motion. This approach can be readily applied to image any atomic or molecular system, as long as it hosts a three-level system.

Superresolution microscopy has revolutionized the fields of chemistry and biology by resolving features at the molecular level. In atomic physics, such a scheme can be applied to resolve the atomic density distribution beyond the diffraction limit and to perform quantum control. Here we demonstrate superresolution imaging based on the nonlinear response of atoms to an optical pumping pulse. With this technique, the atomic density distribution can be imaged with a full-width-at-half-maximum resolution of 32(4) nm and a localization precision below 500 pm. The short optical pumping pulse of $1.4\mu \mathrm{s}$ enables us to resolve fast atomic dynamics within a single lattice site. A by-product of our scheme is the emergence of moiré patterns on the atomic cloud, which we show to be immensely magnified images of the atomic density in the lattice.

Strong magnetic field induces at least two phase transitions in graphite beyond the quantum limit where many-body effects are expected. We report on a study using a state-of-the-art nondestructive magnet allowing us to attain 90.5 T at 1.4 K, which reveals a new field-induced phase and evidence that the insulating state destroyed at 75 T is an excitonic condensate of electron-hole pairs. By monitoring the angle dependence of in-plane and out-of-plane magnetoresistance, we distinguish between the role of cyclotron and Zeeman energies in driving various phase transitions. We find that, with the notable exception of the transition field separating the two insulating states, the threshold magnetic field for all other transitions displays an exact cosine angular dependence. Remarkably, the threshold field for the destruction of the second insulator (phase B) is temperature independent with no detectable Landau-level crossing nearby. We conclude that the field-induced insulator starts as a weak-coupling density wave but ends as a strong-coupling excitonic insulator of spin-polarized electron-hole pairs.

To isolate individual neutral atoms in microtraps, experimenters have long harnessed molecular photoassociation to make atom distributions sub-Poissonian. While a variety of approaches have used a combination of attractive (red-detuned) and repulsive (blue-detuned) molecular states, to date all experiments have been predicated on red-detuned cooling. In our work, we present a shifted perspective—namely, the efficient way to capture single atoms is to eliminate red-detuned light in the loading stage and use blue-detuned light that both cools the atoms and precisely controls trap loss through the amount of energy released during atom-atom collisions in the photoassociation process. Subsequent application of red-detuned light then assures the preparation of maximally one atom in the trap. Using $\mathrm{\Lambda }$-enhanced gray-molasses for loading, we study and model the molecular processes and find we can trap single atoms with 90% probability even in a very shallow optical tweezer. Using 100 traps loaded with 80% probability, we demonstrate one example of the power of enhanced loading by assembling a grid of 36 atoms using only a single move of rows and columns in 2D. Our insight is key in scaling the number of particles in a bottom-up quantum simulation and computation with atoms, or even molecules.

Each living species carries a complex DNA sequence that determines their unique features and functionalities. It is generally assumed that life started from a random pool of oligonucleotide sequences, generated by a prebiotic polymerization of nucleotides. The mechanism that initially facilitated the emergence of sequences that code for the function of the first species from such a random pool of sequences remains unknown. It is a central problem of the origin of life. An interesting option would be a self-selection mechanism by spontaneous symmetry breaking. Initial concentration fluctuations of specific sequence motifs would have been amplified and outcompeted less abundant sequences, enhancing the signal to noise to replicate and select functional sequences. Here, we demonstrate with experimental and theoretical findings that templated ligation would provide such a self-selection. In templated ligation, two adjacent single sequences strands are chemically joined when a third complementary strand sequence brings them in close proximity. This simple mechanism is a likely side product of a prebiotic polymerization chemistry once the strands reach the length to form double-stranded species. As shown here, the ligation gives rise to a nonlinear replication process by the cooperative ligation of matching sequences which self-promote their own elongation. This process leads to a cascade of enhanced template binding and faster ligation reactions. A requirement is the reshuffling of the strands by thermal cycling, enabled, for example, by microscale convection. By using a limited initial sequence space and performing long-term ligations, we find that complementary sequences with an initially higher concentration prevail over either noncomplementary or less-concentrated sequences. The latter die out by the molecular degradation that we simulate in the experiment by serial dilution. The experimental results are consistent with both explicit and abstract theory models that are generated considering the ligation rates determined experimentally. Previously, other nonlinear modes of replication such as hypercycles have been discussed to overcome instabilities from first-order replication dynamics such as the error catastrophe and the dominance of structurally simple but fast-replicating sequences, known as the Spiegelman problem. Assuming that templated ligation is driven by the same chemical mechanism that generates prebiotic polymerization of oligonucleotides, the mechanism could function as a missing link between polymerization and the self-stabilized replication, offering a pathway to the autonomous emergence of Darwinian evolution for the origin of life.

Two- or three-dimensional metals are usually well described by weakly interacting, fermionic quasiparticles. This concept breaks down in one dimension due to strong Coulomb interactions. There, low-energy electronic excitations are expected to be bosonic collective modes, which fractionalize into independent spin- and charge-density waves. Experimental research on one-dimensional metals is still hampered by their difficult realization, their limited accessibility to measurements, and by competing or obscuring effects such as Peierls distortions or zero bias anomalies. Here we overcome these difficulties by constructing a well-isolated, one-dimensional metal of finite length present in ${\mathrm{MoS}}_2$ mirror-twin boundaries. Using scanning tunneling spectroscopy we measure the single-particle density of the interacting electron system as a function of energy and position in the 1D box. Comparison to theoretical modeling provides unambiguous evidence that we are observing spin-charge separation in real space.

Spontaneous emergence of self-organized patterns and their bifurcations towards a regime of complex dynamics in nonequilibrium dissipative systems is a paradigm of phase transition. Indeed, the behavior of these patterns in the highly nonlinear regime remains less explored, even in recent high-quality-factor resonators such as Kerr-nonlinear optical ones. Here, we investigate theoretically and experimentally the alteration of the resulting Kerr frequency combs from the weakly to the highly nonlinear regime, in the frameworks of spatiotemporal chaos, and dissipative phase transitions. We reveal the existence of a striking and easily accessible scenario of spatiotemporal chaos, free of cavity solitons, in a monostable operating regime, wherein a transition to amplitude turbulence via spatiotemporal intermittency is evidenced. Moreover, statistics of the light bursts in the resulting turbulent regime unveils the existence of rogue waves as extreme events characterized by long-tail statistics.

We derive a quantum limit to the sensitivity of laser interferometric gravitational-wave detectors from optical-loss-induced dissipation, analogous to the sensitivity limit from the mechanical dissipation. It applies universally to different interferometer configurations and cannot be surpassed unless the optical properties of the interferometer are improved. This result provides an answer to the long-standing question of how far we can push the detector sensitivity given the state-of-the-art optics.

We explore, both experimentally and theoretically, the response of an elongated Bose-Einstein condensate to modulated interactions. We identify two distinct regimes differing in modulation frequency and modulation strength. Longitudinal surface waves are generated either resonantly or parametrically for modulation frequencies near the radial trap frequency or twice the trap frequency, respectively. The dispersion of these waves, the latter being a Faraday wave, is well reproduced by a mean-field theory that accounts for the 3D nature of the elongated condensate. In contrast, in the regime of lower modulation frequencies, we find that no clear resonances occur, but with an increased modulation strength, the condensate forms an irregular granulated distribution that is outside the scope of a mean-field approach. We find that the granulated condensate is characterized by large quantum fluctuations and correlations, which are well described with single-shot simulations obtained from wave functions computed by a beyond-mean-field theory at zero temperature, the multiconfigurational time-dependent Hartree for bosons method.

We study theoretically and experimentally the emergence of supersolid properties in a dipolar Bose-Einstein condensate. The theory reveals a ground state phase diagram with three distinct regimes—a regular Bose-Einstein condensate and incoherent and coherent arrays of quantum droplets. The coherent droplets are connected by a background condensate, which leads—in addition to the periodic density modulation—to a robust phase coherence throughout the whole system. We further theoretically demonstrate that we are able to dynamically approach the ground state in our experiment and that its lifetime is limited only by three-body losses. Experimentally we probe and confirm the signatures of the phase diagram by observing the in situ density modulation as well as the phase coherence using matter wave interference.

The interaction of intense laser beams with plasmas created on solid targets involves a rich nonlinear physics. Because such dense plasmas are reflective for laser light, the coupling with the incident beam occurs within a thin layer at the interface between plasma and vacuum. One of the main paradigms used to understand this coupling, known as the Brunel mechanism, is expected to be valid only for very steep plasma surfaces. Despite innumerable studies, its validity range remains uncertain, and the physics involved for smoother plasma-vacuum interfaces is unclear, especially for ultrahigh laser intensities. We report the first comprehensive experimental and numerical study of the laser-plasma coupling mechanisms as a function of the plasma interface steepness, in the relativistic interaction regime. Our results reveal a clear transition from the temporally periodic Brunel mechanism to a chaotic dynamic associated to stochastic heating. By revealing the key signatures of these two distinct regimes on experimental observables, we provide an important landmark for the interpretation of future experiments.

We numerically analyze the landscape governing the evolution of the vibrational dynamics of hard disk glasses as the density increases towards jamming. We find that the dynamics becomes slow, spatially correlated, and starts to display aging dynamics across an avoided Gardner transition, with a phenomenology that resembles three-dimensional observations. We carefully analyze the behavior of single glass samples, and find that the emergence of aging dynamics is controlled by the apparition of a complex organization of the landscape that splits into a remarkable hierarchy of minima as jamming is approached. Our results show that the mean-field prediction of a Gardner phase characterized by an ultrametric structure of the landscape provides a useful description of finite-dimensional systems, even when the Gardner transition is avoided.

Dynamic diffusion of molecular solutes in concentrated electrolytes plays a critical role in many applications but is notoriously challenging to measure and model. This challenge is particularly true in the extreme case of ionic liquids (ILs), fluids composed entirely of cations and anions. Solute diffusivities in ILs show a strong concentration dependence, broadening the already vast IL design space and rendering conventional, sample-by-sample measurements impractical for screening. To gain better mechanistic insight into transport in this class of fluids, here we demonstrate a method to visualize the spatiotemporal evolution of concentration fields using microfluidic Fabry-Perot interferometry, enabling diffusivity measurements over an entire composition range within a single experiment. We focus on the absorption and diffusion of water, as both a model solute and a ubiquitous contaminant, within alkylmethylimidazolium-halide ILs. Notably, the Stokes-Einstein relation underpredicts water diffusivities ten- to 50-fold, indicating that water does not experience these ILs as continuum liquids. Based on these measurements, together with wide-angle x-ray scattering and pulsed-field gradient NMR measurements, we propose a new mechanistic framework in which water molecules hop between ion pairs within the IL, which acts as an immobile matrix over timescales relevant for water diffusion. In this case, diffusion is an activated process, with hops between hydrogen-bonding sites over an energetic barrier that decreases linearly with the water fraction. The functional form of the activation energy is consistent with NMR chemical shift measurements, which indicate that hydrogen bonding weakens in linear proportion to the water fraction. This simple model contains the key ingredients required to accurately predict the measured trends in diffusivity—an (Arrhenius) temperature dependence and an exponential composition dependence—for a range of cations, anions, water contents, and temperatures. Our results suggest a general mechanism for anomalously fast diffusion in ILs, where solutes “hop” between binding sites more quickly than the ions rearrange.

We experimentally investigate the effects of parametric instabilities on the short-time heating process of periodically driven bosons in 2D optical lattices with a continuous transverse (tube) degree of freedom. We analyze three types of periodic drives: (i) linear along the $x$-lattice direction only, (ii) linear along the lattice diagonal, and (iii) circular in the lattice plane. In all cases, we demonstrate that the Bose-Einstein condensate (BEC) decay is dominated by the emergence of unstable Bogoliubov modes, rather than scattering in higher Floquet bands, in agreement with recent theoretical predictions. The observed BEC depletion rates are much higher when shaking along both the $x$ and $y$ directions, as opposed to only $x$ or only $y$. We also report an explosion of the decay rates at large drive amplitudes and suggest a phenomenological description beyond the Bogoliubov theory. In this strongly coupled regime, circular drives heat faster than diagonal drives, which illustrates the nontrivial dependence of the heating on the choice of drive.