Experiments using 3D Lagrangian tracking are used to investigate Kolmogorov scaling below the bubble size in bubble-induced turbulence (BIT). Second- and third-order structure functions reveal approximate Kolmogorov scaling for homogeneous bubble swarms. A new scaling for the kinetic energy dissipation rate is derived and shown to be in excellent agreement with the data. Using this we predict the scale separation below the bubble size as a function of the parameters and find that a large inertial range is not possible in BIT since bubbles of the required size would quickly break down.

Lithium is a typical quantum solid, characterized by cubic structures at ambient pressure. As the pressure increases, it forms more complex structures and undergoes a metal-to-semiconductor transformation, complicating theoretical and experimental analyses. We employ the neural canonical transformation approach, a variational method based on probabilistic generative models, to investigate the quantum anharmonic effects in lithium solids at finite temperatures. This approach combines a normalizing flow for phonon excited-state wave functions with a probabilistic model for the occupation of energy levels, optimized jointly to minimize the free energy. Our results indicate that quantum anharmonicity lowers the bcc-fcc transition temperature compared to classical molecular dynamics predictions. At high pressures, the predicted fractional coordinates of lithium atoms in the cI16 structure show good quantitative agreement with experimental observations. Finally, contrary to previous beliefs, we find that the poor metallic oC88 structure is stabilized by the potential energy surface obtained via high-accuracy electronic structure calculations, rather than thermal or quantum effects.

Lattice degrees of freedom (d.o.f.) may induce quantum disorder (QD) when nuclear tunneling outvies long-range order, but conventional phonon theory is incapable of describing such QD phases. Here we develop a method based on path-integral molecular dynamics to solve this problem. Its accuracy is verified in a double-well chain model and it is applied to a real material from first principles. A quantum order-disorder-order phase transition sequence is demonstrated when varying the strength of quantum fluctuations using the lattice constants as the tuning factor. Combining the excitation spectra and Rényi entanglement entropy, we pinpoint the QD region. This picture may be general in lattice systems having soft phonon modes, not limited to quantum paraelectricity, in which novel entangled lattice motion and its coupling with other d.o.f. can be expected.

Two-dimensional (2D) Dirac states and Dirac points with linear dispersion are the hallmark of graphene, topological insulators, semimetals, and superconductors. Lowering a symmetry by the ferroelectric polarization opens the gap in Dirac points and introduces finite Berry curvature. Combining this with Dirac points detached from high symmetry points of the Brillouin zone offers additional ways to tailor topological properties. We explore this concept by studying topological phenomena emerging in 2D materials with movable Dirac points and broken out-of-plane mirror reflection. The resulting topological kink states and Berry curvature dipoles are changed by movable 2D Dirac points with experimental signatures in electrical conductance and second-harmonic nonlinear Hall conductivity. We identify materials platforms where our predictions can be realized and support that with the first-principles results for ${\mathrm{Cl}}_2{\mathrm{Rh}}_2{\mathrm{S}}_2$-GeS junction.

Altermagnets exhibit characteristics akin to antiferromagnets, with spin-split anisotropic bands in momentum space. ${\mathrm{RuO}}_2$ has been considered as a prototype altermagnet; however, recent reports have questioned altermagnetic ground state in this material. In this Letter, we demonstrate spin-dependent tunneling magnetoresistance (TMR) in ${\mathrm{RuO}}_2$-based magnetic tunnel junctions, which suggests the spin-splitted anisotropic band structure of our ${\mathrm{RuO}}_2$ films. The observed TMR is contingent on the direction of the Néel vector of ${\mathrm{RuO}}_2$ and reverse its sign by the inversion of the Néel vector. These results reflect the altermagnetic nature of ${\mathrm{RuO}}_2$ and highlight its potential for spintronic applications, leveraging the combined strengths of ferromagnetic and antiferromagnetic systems.

Epithelial morphogenesis is a process through which simple cellular sheets are shaped into complex tissues and organs in a developing animal. From a physics perspective, understanding any shape change requires knowing the active forces driving its dynamics, as well as the material properties, i.e., the rheology, of the material that is undergoing the deformation. Despite a long-standing effort, rheological properties of embryonic tissues have remained elusive. Here, we develop a minimal theory providing a comprehensive explanation of rheological measurements characterizing the mechanics of epithelia in the early fly embryo. Our theory explains a key experimental observation: when subjected to concentrated pulling force, the embryonic epithelium of the fruit fly Drosophila melanogaster deforms following a power law with an exponent of $1/2$. All dimensional parameters of our theory are constrained by direct measurements and have allowed us to estimate the spring constant of an individual cellular edge. We show that stress relaxation (attributable to actin turnover), stretching elasticity of individual cellular edges, and the floppy topology of the cellular network are the sole physical properties governing tissue rheology on the developmentally relevant time scale of 1–10 minutes.

Quantum criticality often lies beyond the scope of the conventional Landau paradigm, and a unifying framework has yet to emerge, due in part to the wide variety of quantum orders. We propose a geometric approach to quantum phase transitions that shifts focus from microscopic order to the competition between noncommuting operators. This competition is encoded in the boundary geometry of their expectation values, defining a quantum observable space. We show that quantum phase transitions occur at zero-curvature points on the quantum observable space boundary, signaling maximal commutativity and suggesting an underlying integrable structure at criticality.

Competition among repetitive measurements of noncommuting observables and unitary dynamics can give rise to a wide variety of entanglement phases. Here, we propose a general framework based on Lyapunov analysis to characterize topological properties in monitored quantum systems through their spectrum and many-body topological invariants. We illustrate this framework by analyzing ($1+1$)-dimensional monitored circuits for Majorana fermions, which are known to exhibit topological and trivial area-law entangled phases as well as a critical phase with sub-volume-law entanglement. Through the Lyapunov analysis, we identify the presence (absence) of edge-localized zero modes inside the bulk gap in the topological (trivial) phase and a bulk gapless spectrum in the critical phase. Furthermore, by suitably exploiting the fermion parity with twisted measurement outcomes at the boundary, we construct a topological invariant that distinguishes the two area-law phases and dynamically characterizes the critical phase. Our framework thus provides a general route to extend the notion of bulk-edge correspondence to monitored quantum dynamics.

We classify quantum cellular automata whose cells are qubits, on hypercubic lattices ${\mathbb{Z}}^s$, with the von Neumann neighborhood scheme, in terms of realizability as finite-depth quantum circuits. We show the most general structure of such automata and use its characterisation to simulate a few steps of evolution and evaluate the rate of entanglement production between one cell and its surroundings.

We show that interactions violating the conservation of lepton numbers in the neutrino sector could significantly alter the standard low entropy picture for the presupernova collapsing core of a massive star. A rapid neutrino-antineutrino equilibration leads to entropy generation and enhanced electron capture and, hence, a lower electron fraction than in the standard model. This would affect the downstream core evolution, the prospects for a supernova explosion, and the emergent neutrino signal. If realized by lepton-number-violating neutrino self-interactions (LNV $\nu \mathrm{SI}$), the relevant mediator mass and coupling ranges can be probed by future accelerator-based experiments.

We report on a search for millicharged particles (mCPs) produced in cosmic ray atmospheric interactions using data collected during the first science run of the LUX-ZEPLIN experiment. The mCPs produced by two processes—meson decay and proton bremsstrahlung—are considered in this study. This search utilized a novel signature unique to liquid xenon (LXe) time projection chambers, allowing sensitivity to mCPs with masses ranging from 10 to $1000\mathrm{MeV}/{\mathrm{c}}^2$ and fractional charges between 0.001 and 0.02 of the electron charge ($e$). With an exposure of 60 live days and a 5.5 metric ton fiducial mass, we observed no significant excess over background. This represents the first experimental search for atmospheric mCPs and the first search for mCPs using an underground LXe experiment.

We report the first experimental demonstration of squeezed lasing in a reservoir-engineered optical parametric oscillator (OPO). The OPO provides a basis of squeezed states and parametric amplification in lasing emission, whose vacuum reservoir is coupled to a squeezed vacuum generated by a second OPO. With a precisely controlled squeezing angle and strong squeezing injection, the parametric interaction in the first OPO is exponentially enhanced. It successfully circumvents the decoherence in the system, and eliminates the undesired noise of spontaneous photon emission in the OPO. As a result, the amplified parametric process simultaneously reserves the coherence and quantum properties in the first OPO, and yields a $-6.1\mathrm{dB}$ squeezed laser in optical domain with a narrow linewidth and high brightness. Our work sheds light on potential applications of squeezed lasing in quantum metrology and quantum optics.

In one-dimensional quasiperiodic systems, only a few models with exact mobility edges (MEs) have been constructed using generalized self duality theory, Avila’s global theory, or the renormalization group method. This raises an intriguing question of whether we can realize more physical models with exact solvable MEs. In this Letter, we uncover the hidden self duality within a class of quasiperiodic network models constituted by periodic and quasiperiodic sites. Although the original Hamiltonians appear to lack self duality, their effective Hamiltonians obtained by integrating out the periodic sites exhibit self duality, which yield MEs. The well-studied mosaic model, which is the simplest case of quasiperiodic network models, was previously thought to exhibit MEs due to the absence of self duality, but we show that they actually arise from the hidden self duality. Using the effective Hamiltonian, we further introduce the concept of resonant states to understand the shape of MEs. Finally, we present in detail how to determine the MEs in various network models, including some non-Hermitian models, based on the hidden self duality. These predictions can be experimentally realized using optical and acoustic waveguide arrays. Our work can greatly advance our understanding of MEs in Anderson transition.

Fractal geometries, characterized by self-similar patterns and noninteger dimensions, provide an intriguing platform for exploring topological phases of matter. In this Letter, we introduce a theoretical framework that leverages isospectral reduction to effectively simplify complex fractal structures, revealing the presence of topologically protected boundary and corner states. Our approach demonstrates that fractals can support topological phases, even in the absence of traditional driving mechanisms such as magnetic fields or spin-orbit coupling. The isospectral reduction not only elucidates the underlying topological features but also makes this framework broadly applicable to a variety of fractal systems. Furthermore, our findings suggest that these topological phases may naturally occur in materials with fractal structures found in nature. This Letter opens new avenues for designing fractal-based topological materials, advancing both theoretical understanding and experimental exploration of topology in complex, self-similar geometries.

Motivated by advances in pump-probe experiments and light-driven phenomena, we theoretically study the impact of pumped and driven phonons in Mott insulators which host multipole moments, thus going beyond conventional dipolar magnetism. As a case study, we examine pseudospin-$1/2$ Mott insulators hosting quadrupolar and octupolar moments, and investigate the effect of resonantly exciting ${\mathcal{E}}_g$ phonon modes which couple linearly to the quadrupoles. We show that this leads to multipolar precession, with the backaction resulting in pseudochiral phonon dynamics in the octupolar ordered phase. We further study the impact of a short-time two-phonon drive, showing that it can induce the buildup of octupolar order or even switch its sign on picosecond timescales. Our results are obtained using a Monte Carlo code incorporating phonons, molecular dynamics simulations to numerically integrate the coupled spin-phonon equations of motion, and analytical Floquet theory. Our work shows how driven phonons can probe and control hidden orders in solids.

Spatial structuring of materials at subwavelength scales underlies the concept of metamaterials possessing exotic properties beyond those of the constituent media. Temporal modulation of material parameters enables further functionalities. Here, we show that high-frequency oscillations of spatially uniform magnetization generate an effective dynamic axion field embedding the amplitude and phase of magnetization oscillations. This allows one to map ultrafast magnetization dynamics using a probe signal with much lower frequency.

Embedding materials in optical cavities has emerged as an intriguing perspective for controlling quantum materials, but a key challenge lies in measuring properties of the embedded matter. Here, we propose a framework for probing strongly correlated cavity-embedded materials through direct measurements of cavity photons. We derive general relations between photon and matter observables inside the cavity, and show how these can be measured via the emitted photons. As an example, we demonstrate how the entanglement phase transition of an embedded ${\mathrm{H}}_2$ molecule can be accessed by measuring the cavity photon occupation, and showcase how dynamical spin correlation functions can be accessed by measuring dynamical photon correlation functions. Our framework provides an all-optical method to measure static and dynamic properties of cavity-embedded materials.