Constant-potential molecular dynamics (MD) simulations are indispensable for understanding the structure, capacitance, and dynamics of electrical double layers (EDLs) at the atomistic level. However, the classical constant-potential method, relying on the so-called “fluctuating charges” to keep electrode equipotential, overlooks quantum effects on the electrode and always underestimates EDL capacitance for typical metal electrode and aqueous electrolyte interfaces. Here, we propose a constant potential method accounting for electron spillover on the outermost nuclei of the electrode. For EDLs at Au(111) electrodes, our MD simulation reveals bell-shaped capacitance curves in magnitude and shape both quantitatively consistent with experiments. It unveils the electrode-polarization-dependent local electric fields, agreeing with experimental observations of redshift vibration of interfacial water under negative polarization and predicting a blueshift under positive polarization, and further identifies geometry dependence of two timescales during charging.

We show how a driven-dissipative cavity coupled to a collective ensemble of atoms can dynamically generate metrologically useful spin-squeezed states. In contrast to other dissipative approaches, we do not rely on complex engineered dissipation or input states, nor do we require tuning the system to a critical point. Instead, we utilize a strong symmetry, a special type of symmetry that can occur in open quantum systems and emerges naturally in systems with collective dissipation, such as superradiance. This symmetry preserves coherence and allows for the accumulation of an atom number-dependent Berry phase which in turn creates spin-squeezed states via emergent one axis twisting dynamics. This work shows that it is possible to generate entanglement in an atom-cavity resonant regime with macroscopic optical excitations of the system, going beyond the typical dispersive regime with negligible optical excitations often utilized in current cavity-QED experiments.

We introduce the notion of jets, states of collinear flux-tube excitations. We argue for the analyticity, crossing, and unitarity of the multiparticle scattering of these jets and, through the S-matrix bootstrap, place bounds on a set of finite-energy multiparticle sum rules. Such bounds define a matrioska with a smaller and smaller allowed regions as we impose more constraints. The Yang-Mills flux tube, as well as other interesting flux-tube theories recently studied through lattice simulations, lie inside a tiny island hundreds of times smaller than the most general space of allowed theories.

We report on high-precision atomic mass measurements of ${}^{148–153}\mathrm{La}$ and ${}^{151}\mathrm{Ce}$ performed with the JYFLTRAP double Penning trap using the phase-imaging ion-cyclotron-resonance technique. The masses of ${}^{152,153}\mathrm{La}$ were experimentally determined for the first time. We confirm the sharp kink in the two-neutron separation energies at the neutron number $N=93$ in the cerium ($Z=58$) isotopic chain. Our precision mass measurements of the most exotic neutron-rich lanthanum ($Z=57$) isotopes reveal a unexpected sudden increase in two-neutron separation energies from $N=92$ to $N=93$. Unlike in the cerium isotopic chain, the kink is not sharp but extends to $N=94$ forming a prominent bump. The gain in energy is about 0.4 MeV, making it one of the strongest changes in two-neutron separation energies over the whole chart of nuclides, away from nuclear shell closures. The results, correlated with a predicted onset of quadrupole deformation for $N\ge 92$, call for further studies to elucidate the structure of neutron-rich lanthanum isotopes.

We present the first assessment, using hybrid PIC simulations, of the role of nonlinear Landau damping in the process of self-generated scattering in a high $\beta$ plasma, conditions appropriate for CR scattering in the halo of the Galaxy. The drift speed of CRs reduces due to scattering, but remains super-Alfvénic due to damping. Furthermore, this damping process manifests itself in the form of heating of the background plasma. We also show that the damping leads to an inverse cascade process, consisting of producing nonresonant large scale modes, a novel result with many potential phenomenological implications.

We experimentally demonstrate similarity laws for capacitive radio-frequency (rf) plasmas, showing that two rf discharges are scale-invariant in geometrically similar systems in which the gas pressure, gap dimension, and driving frequency are proportionally tuned. Spatiotemporal distributions of the excitation rate are measured based on phase-resolved optical emission spectroscopy, and the tendencies of the excitation dynamics scaling with control parameters are presented and agree well with particle-in-cell simulations. Furthermore, similarity-based scaling networks are established, which extensively correlate the discharge states (i.e., the initial, intermediate, and similarity states), enabling an effective strategy for determining scaling relations with fewer experiments. The framework of the scaling networks is interpreted based on the kinetic Boltzmann equation coupled with Poisson’s equation. The present work reveals the nature of discharge similarity and provides an additional knob for the exploration of upscaled rf plasma sources for industrial applications, such as large-area etching facilities.

We theoretically study the quantum spin Hall insulator (QSHI) in a perpendicular magnetic field. In the noninteracting case, the QSHI with space inversion and/or uniaxial spin rotation symmetry undergoes a topological transition into a normal insulator phase at a critical magnetic field $B_{\mathrm{c}}$. The exciton condensation in the lowest Landau levels is triggered by Coulomb interactions in the vicinity of $B_{\mathrm{c}}$ at low temperature and spontaneously breaks the inversion and the spin rotation symmetries. We propose that the electron spin resonance spectroscopy with the ac magnetic field also aligned in the perpendicular direction can directly probe the exciton condensation order. Our results should apply to QSHIs such as the $\mathrm{InAs}/\mathrm{GaSb}$ quantum wells and monolayer transition-metal dichalcogenides.

The study of spreading in networks presents a fascinating topic with a wide array of practical applications. Various strategies have been proposed to attack or immunize networks. However, it is often not feasible or necessary to consider the entire network in the context of real-world systems. Here, we focus on a certain group of target nodes with the aim of disconnecting them from the global network structure. For instance, it becomes possible to effectively prevent the transmission of the disease to vulnerable populations, such as infants and the elderly, by isolating some specific nodes such as their caretakers during the epidemic. From this perspective of targeted avoidance, we introduce a series of target centrality indicators and apply them to segment the target nodes from the giant component of the network. Additionally, we propose a more effective iterative graph-segmentation method for targeted immunization. Our experimental findings reveal that our proposed method can substantially reduce the number of nodes required for removal when compared with the methods based on target centrality, which implies a significant cost effectiveness in isolating target nodes from the rest of the network. Finally, we verify our method on a large mobility network in the scenario of the COVID-19 pandemic, and find that our method can effectively protect the elderly by immunizing or isolating a very small group of nodes.

Understanding quantum phenomena that go beyond classical concepts is a focus of modern quantum physics. Here, we show how the theory of non-negative polynomials emerging around Hilbert’s 17th problem, can be used to optimally exploit data capturing the nonclassical nature of light. Specifically, we show that non-negative polynomials can reveal nonclassicality in data even when it is hidden from standard detection methods up to now. Moreover, the abstract language of non-negative polynomials also leads to a unified mathematical approach to nonclassicality for light and spin systems, allowing us to map methods for one to the other. Conversely, the physical problems arising also inspire several mathematical insights into characterization of non-negative polynomials.

We investigate the hidden amplitude zeros which describe a nontrivial vanishing of scattering amplitudes on special external kinematics. We first prove that every type of hidden zero is equivalent to what we call a “subset” enhanced scaling under Britto-Cachazo-Feng-Witten shifts for any rational function built from planar Lorentz invariants $X_{ij}=(p_i+p_{i+1}+\cdots +p_{j-1}{)}^2$. This directly applies to $\mathrm{Tr}({\varphi }^3)$, nonlinear sigma models, or Yang-Mills-scalar amplitudes, revealing a novel type of enhanced UV scaling in these theories. We also use this observation to prove the conjecture that $\mathrm{Tr}({\varphi }^3)$ amplitudes are uniquely fixed by the zeros, up to an overall normalization, when assuming an ordered and local propagator structure and trivial numerators. In this context, unitarity (residue factorization) may be viewed as a consequence of the zeros. For Yang-Mills theory, we conjecture the zeros, combined with the Bern-Carrasco-Johansson color-kinematic duality in the form of amplitude relations, uniquely fix the $\lfloor n/2\rfloor$ distinct polarization structures of $n$-point gluon amplitudes. Our approach opens a new avenue for understanding previous similar uniqueness results, and also extending them beyond tree level for the first time.

We study a single exactly massless staggered fermion in the fundamental representation of an SU(2) gauge group. We utilize an nHYP-smeared fermion action supplemented with additional heavy Pauli-Villars fields that serve to decrease lattice artifacts. The phase diagram exhibits a clear two-phase structure with a conformal phase at weak coupling and a novel new phase, the symmetric mass generation (SMG) phase, appearing at strong coupling. The SMG phase is confining with all states gapped and chiral symmetry unbroken. Our finite size scaling analysis provides strong evidence that the phase transition between these two phases is continuous, which would allow for the existence of a continuum SMG phase. Furthermore, the renormalization group flows are consistent with a $\beta$ function that vanishes quadratically at the new fixed point, suggesting that the $N_f=4$ flavor SU(2) gauge theory lies at the opening of the conformal window.

The first study of $J/\psi \varphi$ production in diffractive processes in proton-proton collisions is presented. The study is based on an LHCb dataset recorded at center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $5{\mathrm{fb}}^{-1}$. The data disfavor a nonresonant $J/\psi \varphi$ production but are consistent with a resonant model including several resonant states observed previously only in $B^{+}\to J/\psi \varphi K^{+}$ decays. The ${\chi }_{c0}(4500)$ state is observed with a significance over $6\sigma$ and the ${\chi }_{c1}(4274)$ is confirmed with a significance of more than $4\sigma$.

In doped transition metal dichalcogenides, optically created excitons (bound electron-hole pairs) can strongly interact with a Fermi sea of electrons to form Fermi polaron quasiparticles. When there are two distinct Fermi seas, as is the case in ${\mathrm{WSe}}_2$, there are two flavors of lowest-energy (attractive) polarons—singlet and triplet—where the exciton is coupled to the Fermi sea in the same or opposite valley, respectively. Using two-dimensional coherent electronic spectroscopy, we analyze how their quantum decoherence evolves with doping density and determine the condition under which stable Fermi polarons form. Because of the large oscillator strength associated with these resonances, intrinsic quantum dynamics of polarons as well as valley coherence between coupled singlet- and triplet polarons occur on subpicosecond timescales. Surprisingly, we find that a dark-to-bright state conversion process leads to a particularly long-lived singlet polaron valley polarization, persisting up to 200–800 ps. Valley coherence between the singlet- and triplet polaron is correlated with their energy fluctuations. Our finding provides valuable guidance for the electrical and optical control of spin and valley indexes in atomically thin semiconductors.

Spin noise spectroscopy has become a widespread technique to extract information on spin dynamics in atomic and solid-state systems, in a potentially nonperturbative way. Here we experimentally demonstrate a new approach in spin noise spectroscopy, based on the detection of single photons. Because of the large spin-dependent polarization rotations provided by a deterministically coupled quantum dot-micropillar device, giant spin noise signals induced by a single-hole spin are extracted in the form of photon-photon cross-correlations. Ultimately, such a technique can be extended to an ultrafast regime probing mechanisms down to few tens of picoseconds.

We devise a Floquet theory of longitudinal and dispersive readout in circuit quantum electrodynamics (cQED). By studying qubits coupled to cavity photons and driven at the resonance frequency of the cavity ${\omega }_{\mathrm{r}}$, we establish a universal connection between the qubit ac Stark shift and the longitudinal and dispersive coupling to photons. We find that the longitudinal coupling $g_{\parallel }$ is controlled by the slope of the ac Stark shift as function of the driving strength $A_{\mathrm{q}}$, while the dispersive shift $\chi$ depends on its curvature. The two quantities become proportional to each other in the weak drive limit ($A_{\mathrm{q}}\to 0$). Our approach unifies the adiabatic limit (${\omega }_{\mathrm{r}}\to 0$)—where $g_{\parallel }$ is generated by the static spectrum curvature (or quantum capacitance)—with the diabatic limit, where ${\omega }_{\mathrm{r}}$ is large and the static spectrum plays no role. We derive analytical results supported by exact numerical simulations. We apply them to superconducting and spin-hybrid cQED systems, showcasing the flexibility of faster-than-dispersive longitudinal readout.