Pressure-driven coarsening triggers bubble rearrangements in liquid foams. Our experiments show that changing the continuous phase rheology can alter these internal bubble dynamics without influencing the coarsening kinetics. Through bubble tracking, we find that increasing the matrix yield stress permits bubble growth without stress relaxation via neighbor-switching events, promoting more spatially homogeneous rearrangements and decoupling bubble growth from mobility. This eventually leads to a structural change that directly impacts the foam mechanical and stability properties, essential for applications in various technological and industrial contexts.

We observe strong dynamical suppression of optically induced loss in a weakly interacting Fermi gas as the $s$-wave scattering length is increased. A single trapped cigar-shaped cloud behaves as a large spin lattice in energy space with a tunable Heisenberg Hamiltonian. The loss suppression occurs as the lattice transitions into a magnetized state, where the fermionic nature of the atoms inhibits interactions. The data are quantitatively explained by incorporating spin-dependent loss into a quasiclassical collective spin vector model, the success of which enables the application of optical control of effective long-range interactions to this system.

Experimental demonstration of tunable temporal Goos-Hänchen shift (GHS) in synthetic discrete-time heterolattices with scalar and vector gauge potentials is reported. By using Heaviside-function modulation in two fiber loops, we create a sharp gauge-potential interface and observe temporal GHS for total internal reflection (TIR), which manifests as a time delay rather than a spatial shift. The TIR occurs as the incident mode falls into the band gap of transmitted region with band shifting by scalar and vector potential. We find that both scalar and vector potential codetermine GHS by controlling the decay (imaginary part) and oscillation (real part) of a penetrated evanescent wave, in stark contrast to traditional spatial GHS only determined by the decay factor. We also observe diverging characteristics of GHS at band-gap edges where evanescent-to-propagating wave transition occurs. GHS for frustrated total internal reflection (FTIR) by a finite-width evanescent barrier is also demonstrated, which shows saturation properties to the single-interface TIR case under infinite-width limit. Finally, we develop an accumulation measurement method using multiple TIRs to improve the precision for measuring even tinier GHS. The study initiates precise measurement of temporal GHS for discrete-time reflections, which may feature potential applications in precise time-delay control and measurement.

The existence of gapped boundaries of bosonic topological orders can be tested in terms of the vanishing of higher central charges, which can be easily computed in terms of the modular data. For fermionic topological orders, even the chiral central charge admits no simple expression in terms of the modular data. Using the congruence property of representations formed by the modular data, we develop a method that tests whether the higher central charges of a fermionic topological order, including the chiral central charge, vanish. The test can be carried out entirely in terms of the modular data of the super-modular tensor category describing the fermionic topological order, and does not require explicit computation of modular extensions. This leads to a stringent set of easily computable necessary conditions for a fermionic topological order to admit a gapped boundary. We apply our test to known examples of fermionic topological orders to determine which of them potentially admit a gapped boundary.

The dominant noise in an “erasure qubit” is an erasure—a type of error whose occurrence and location can be detected. Erasure qubits have potential to reduce the overhead associated with fault tolerance. To date, research on erasure qubits has primarily focused on quantum computing and quantum networking applications. Here, we consider the applicability of erasure qubits to quantum sensing and metrology. We show theoretically that, for the same level of noise, an erasure qubit acts as a more precise sensor or clock compared to its nonerasure counterpart. We experimentally demonstrate this by artificially injecting either erasure errors (in the form of atom loss) or dephasing errors into a differential optical lattice clock comparison, and observe enhanced precision in the case of erasure errors for the same injected error rate. In the context of a clock with repeated measurement cycles, erasure can improve the stability by a factor of 2. Similar benefits of erasure qubits to sensing can be realized in other quantum platforms like Rydberg atoms and superconducting qubits.

Measuring physical observables requires averaging experimental outcomes over numerous identical measurements. The complete distribution function of possible outcomes or its Fourier transform, known as the full counting statistics, provides a more detailed description. This method captures the fundamental quantum fluctuations in many-body systems and has gained significant attention in quantum transport research. In this Letter, we propose that cusp singularities in the full counting statistics are a novel tool for distinguishing between ordered and disordered phases. As a specific example, we focus on the superfluid-to-Mott transition in the Bose-Hubbard model. Through both analytical analysis and numerical simulations, we demonstrate that the full counting statistics exhibit a cusp singularity as a function of the phase angle in the superfluid phase when the subsystem size is sufficiently large, while it remains smooth in the Mott phase. This discontinuity can be interpreted as a first-order transition between different semiclassical configurations of vortices. We anticipate that our discoveries can be readily tested using state-of-the-art ultracold atom and superconducting qubit platforms.

We develop a general theory of Fermi polarons at nonzero temperature, including particle-hole excitations of the Fermi sea shakeup to arbitrarily high orders. The exact set of equations of the spectral function is derived by using both Chevy ansatz and diagrammatic approach, and their equivalence is clarified to hold in free space only, with an unregularized infinitesimal interaction strength. The correction to the polaron spectral function arising from two-particle-hole excitations is explicitly examined for an exemplary case of Fermi polarons in one-dimensional optical lattices. We find quantitative improvements at low temperatures with the inclusion of two-particle-hole excitations, in both polaron energies and decay rates. Our exact theory of Fermi polarons with arbitrary orders of particle-hole excitations might be used to better understand the intriguing polaron dynamical responses in two or three dimensions, whether in free space or within lattices.

We theoretically show that the spin-spin interactions realized in two-dimensional Mott insulators of large-spin magnetic atoms (such as Cr, Er, or Dy) lead to scalable spin squeezing along the nonequilibrium unitary evolution initialized in a coherent spin state. An experimentally relevant perturbation to the collective squeezing dynamics is offered by a quadratic Zeeman shift, which leads instead to squeezing of individual spins. Making use of a truncated cumulant expansion for the quantum fluctuations of the spin array, we show that, for sufficiently small quadratic shifts, the spin squeezing dynamics is akin to that produced by the paradigmatic one-axis-twisting model—as expected from an effective separation between collective-spin and spin-wave variables. Scalable spin squeezing is shown to be protected by the robustness of long-range ferromagnetic order to quadratic shifts in the equilibrium phase diagram of the system that we reconstruct via quantum Monte Carlo and mean-field theory.

We show a new class of optical silk torsion pendulum (TOP) with zepto-Newton-meter (zNm) sensitivity achieved by exploiting hitherto unknown ultrasoft twist response of tough silk fibers in ultrahigh vacuum. We demonstrate several macroscopic microgram TOPs using three different silk types showing 6 orders of magnitude wide range of sensitivity calibrated using up to zNm optical torques. Remarkably, a nanoscale diameter capture silk exhibits about $20\mathrm{fNm}/\mathrm{rad}$ torsion constant with low damping and responds to sub-400 zNm impulses over many oscillation cycles. We have isolated sub-$3.0\pm 0.2\mathrm{zNm}/\mathrm{s}$ torque velocity sensitivity with an integration time of the order of hours. We show systematic measurements of optical torsional damping induced by well-timed subcycle impulses as well as periodic on-off torquing down to 470 zNm amplitude, in quantitative agreement with model simulations. Our calculation suggests that a 100 nm diameter silk nanofibril can open a route to sub-yocto-Nm sensitive macroscopic TOP thereby making silk sensors attractive for real-world ultrasensitive metrology applications.

We study the buckling of a clamped beam immersed in a creeping flow within a rectangular channel. Via a combination of precision experiments, simulations, and theoretical modeling, we show how the instability depends on a pressure feedback mechanism and rationalize it in terms of dimensionless parameters. As the beam can bend until touching the wall above a critical flow rate, we finally demonstrate how the system can be used as a tunable passive flow selector, effectively redirecting the flow within a designed hydraulic circuit.

Driven-dissipative physics lie at the core of quantum optics. However, the full interplay between a driven quantum many-body system and its environment remains relatively unexplored in the solid state realm. In this Letter, we inspect this interplay beyond the commonly employed stroboscopic Hamiltonian picture based on the specific example of a driven superconductor. Using the Shirley-Floquet and Keldysh formalisms as well as a generalization of the notion of superconducting fitness to the driven case, we show how a drive which anticommutes with the superconducting gap operator generically induces an unusual particle-hole structure in the spectral functions from the perspective of the thermal bath. Concomitant with a driving frequency which is near resonant with the intrinsic cutoff frequency of the underlying interaction, this spectral structure can be harnessed to enhance the superconducting transition temperature. Our work paves the way for further studies for driven-dissipative engineering of exotic phases of matter in solid-state systems.

Enantioselective optical forces have garnered significant attention, because they provide a noninvasive means to separate chiral objects. A promising approach to enhance enantioselective optical forces is spatially overlapping and boosting electric and magnetic fields to create giant superchiral fields. Here, we utilize metasurfaces composed of asymmetric silicon dimers that support two distinct quasibound states in the continuum (quasi BICs). By precisely engineering these quasi BICs, we achieve nearly perfect spatial overlap of electric and magnetic fields near their anticrossing point, resulting in a remarkable ${10}^4$-fold enhancement of the superchiral field. Consequently, the enantioselective optical force exerting on a single molecule exhibits a substantial increase, with magnitude up to $\mathrm{pN}/\mathrm{mW}\mathrm{\mu }{\mathrm{m}}^2$. Furthermore, by encircling the anticrossing point, we can switch the handedness of the superchiral field and the enantioselective optical force. Last, we analyze the dynamics of quasi-BIC-assisted chiral separation, highlighting its potential applications in chiral sensing and sorting, circular dichroism spectroscopy, and pharmacology.

Monitored random circuits, consisting of alternating layers of entangling two-qubit gates and projective single-qubit measurements applied to some fraction $p$ of the qubits, have been a topic of recent interest. In particular, the resulting steady state exhibits a phase transition from highly correlated states with “volume-law” entanglement at $p<p_{\mathrm{c}}$ to localized states with “area-law” entanglement at $p>p_{\mathrm{c}}$. It is hard to access this transition experimentally, as it cannot be seen at the ensemble level. Naively, to observe it one must repeat the experiment until the set of measurement results repeats itself, with likelihood that is exponentially small in the number of measurements. To overcome this issue, we present a hybrid quantum-classical algorithm which creates a matrix product state (MPS) based “unitary mirror” of the projected circuit. Polynomial-sized tensor networks can represent quantum states with area-law entanglement, and so the unitary mirror can well approximate the experimental state above $p_{\mathrm{c}}$ but fails exponentially below it. The breaking of this mirror can thus pinpoint the critical point. We outline the algorithm and how such results would be obtained. We present a bound on the maximum entanglement entropy of any given state that is well represented by an MPS, and from the bound suggest how the volume-law phase can be bounded. We consider whether the entanglement could similarly be bounded from below where the MPS fails. Finally, we present numerical results for small qubit numbers and for monitored circuits with random Clifford gates.

We construct a candidate tree-level gravitational Compton amplitude for a rotating Kerr black hole, for any quantum spin $s=0,1/2,1,\dots ,\infty$, from which we extract the corresponding classical amplitude to all orders in the spin vector $S^{\mu }$. We use multiple insights from massive higher-spin quantum field theory, such as massive gauge invariance and improved behavior in the massless limit. A chiral-field approach is particularly helpful in ensuring correct degrees of freedom, and for writing down compact off-shell interactions for general spin. The simplicity of the interactions is echoed in the structure of the spin-$s$ Compton amplitude, for which we use homogeneous symmetric polynomials of the spin variables. Where possible, we compare to the general-relativity results in the literature, available up to eighth order in spin.

The intensity-difference spectrum technique is applied to record charge-state resolved ion energy spectra from the Coulomb explosion of small Ar clusters under well-resolved laser intensity conditions. The far-reaching control of the experimental parameters permits us to identify a striking change in the expansion pattern of the nanoplasma beyond a given intensity. The simultaneous characterization of ion charge state and energy uncovers that a reduction of the laser intensity leads to a development of low energy cuts in the ion yields, not present at higher fluence. The complex interplay of outer ionization, recombination, ion screening, and the phenomenon of ionization saturation favors a surface-driven expansion at low plasma electron temperatures. With increasing laser intensity a transition into a volume-driven Coulomb explosion is observed.

Understanding topological matter in the fractional quantum Hall (FQH) effect requires identifying the nature of edge state quasiparticles. FQH edge state at the filling factor $\nu =2/3$ in the spin-polarized and unpolarized phases is represented by the two modes of composite fermions (CF) with the parallel or opposite spins described by the chiral Luttinger liquids. Tunneling through a quantum point contact (QPC) between different or similar spin phases is solved exactly. With the increase of the applied voltage, the QPC conductance grows from zero and saturates at $e^2/2h$ while a weak electron tunneling between the edge modes with the same spin transforms into a backscattering carried by the charge $q=e/2$ quasiparticles. These unusual quasiparticles and conductance plateau emerge when one or two CF spin-polarized modes in the QPC tunnel into a single mode. We propose experiments on the applied voltage and temperature dependence of the QPC conductance and noise that can shed light on the nature of edge states and FQH transport.