Cells employ control strategies to maintain a stable size. Dividing at a target size (the “sizer” strategy) is thought to produce the tightest size distribution. However, this result follows from phenomenological models that ignore the molecular mechanisms required to implement the strategy. Here we investigate a simple mechanistic model for exponentially growing cells whose division is triggered at a molecular abundance threshold. We find that size noise inherits the molecular noise and is consequently minimized not by the sizer but by the “adder” strategy, where a cell divides after adding a target amount to its birth size. We derive a lower bound on size noise that agrees with publicly available data from six microfluidic studies on Escherichia coli bacteria.

It has long been known that the lifetimes of superconducting qubits suffer during readout, increasing readout errors. We show that this degradation is due to the anti-Zeno effect, as readout-induced dephasing broadens the qubit so that it overlaps “hot spots” of strong dissipation, likely due to two-level systems in the qubit’s bath. Using a flux-tunable qubit to probe the qubit’s frequency-dependent loss, we accurately predict the change in lifetime during readout with a new self-consistent master equation that incorporates the modification to qubit relaxation due to measurement-induced dephasing. Moreover, we controllably demonstrate both the Zeno and anti-Zeno effects, which can explain both suppression and the rarer enhancement of qubit lifetimes during readout.

We derive an effective field theory describing a pair of gravitationally interacting point particles in an expansion in their mass ratio, also known as the self-force (SF) expansion. The 0SF dynamics are trivially obtained to all orders in Newton’s constant by the geodesic motion of the light body in a Schwarzschild background encoding the gravitational field of the heavy body. The corrections at 1SF and higher are generated by perturbations about this configuration—that is, the geodesic deviation of the light body and the fluctuation graviton—but crucially supplemented by an operator describing the recoil of the heavy body as it interacts with the smaller companion. Using this formalism we compute new results at third post-Minkowskian order for the conservative dynamics of a system of gravitationally interacting massive particles coupled to a set of additional scalar and vector fields.

Engineering pairs of massive particles that are simultaneously correlated in their external and internal degrees of freedom is a major challenge, yet essential for advancing fundamental tests of physics and quantum technologies. In this Letter, we experimentally demonstrate a mechanism for generating pairs of atoms in well-defined spin and momentum modes. This mechanism couples atoms from a degenerate Bose gas via a superradiant photon-exchange process in an optical cavity, producing pairs via a single channel or two discernible channels. The scheme is independent of collisional interactions, fast, and tunable. We observe a collectively enhanced production of pairs and probe interspin correlations in momentum space. We characterize the emergent pair statistics and find that the observed dynamics is consistent with being primarily seeded by vacuum fluctuations in the corresponding atomic modes. Together with our observations of coherent many-body oscillations involving well-defined momentum modes, our results offer promising prospects for quantum-enhanced interferometry and quantum simulation experiments using entangled matter waves.

We report the first experimental demonstration of the replica symmetry breaking (RSB) phenomenon in a fiber laser system supporting standard mode-locking (SML) regime. Though theoretically predicted, this photonic glassy phase remained experimentally undisclosed so far. We employ an ytterbium-based mode-locked fiber laser with a very rich phase diagram. Two phase transitions are observed separating three different regimes: cw, quasi-mode-locking (QML), and SML. The regimes are intrinsically related to the distinct dynamics of intensity fluctuations in the laser spectra. We set the connection between the RSB glassy phase with frustrated modes and onset of $\mathsf{L}$-shaped intensity distributions in the QML regime, which impact directly the replica overlap measure.

We study the statistics of velocity circulation in two-dimensional classical and quantum turbulence. We perform numerical simulations of the incompressible Navier-Stokes and the Gross-Pitaevskii (GP) equations for the direct and inverse cascades. Our GP simulations display clear energy spectra compatible with the double cascade theory of two-dimensional classical turbulence. In the inverse cascade, we found that circulation intermittency in quantum turbulence is the same as in classical turbulence. We compare GP data to Navier-Stokes simulations and experimental data from Zhu et al. [Phys. Rev. Lett. 130, 214001 (2023)]. In the direct cascade, for nearly incompressible GP flows, classical and quantum turbulence circulation displays the same self-similar scaling. When compressibility becomes important, quasishocks generate quantum vortices and the equivalence of quantum and classical turbulence only holds for low-order moments. Our results establish the boundaries of the equivalence between two-dimensional classical and quantum turbulence.

Electrostatic waves play a critical role in nearly every branch of plasma physics from fusion to advanced accelerators, to astro, solar, and ionospheric physics. The properties of planar electrostatic waves are fully determined by the plasma conditions, such as density, temperature, ionization state, or details of the distribution functions. Here we demonstrate that electrostatic wave packets structured with space-time correlations can have properties that are independent of the plasma conditions. For instance, an appropriately structured electrostatic wave packet can travel at any group velocity, even backward with respect to its phase fronts, while maintaining a localized energy density. These linear, propagation-invariant wave packets can be constructed with or without orbital angular momentum by superposing natural modes of the plasma and can be ponderomotively excited by space-time structured laser pulses like the flying focus.

Kagome metals $A{\mathrm{V}}_3{\mathrm{Sb}}_5$ ($A=\mathrm{K}$, Rb, or Cs) exhibit intriguing charge density wave (CDW) instabilities, which interplay with superconductivity and band topology. However, despite firm observations, the atomistic origins of the CDW phases, as well as hidden instabilities, remain elusive. Here, we adopt our newly developed symmetry-adapted cluster expansion method to construct a first-principles-based effective Hamiltonian of ${\mathrm{CsV}}_3{\mathrm{Sb}}_5$, which not only reproduces the established inverse star of David (ISD) phase, but also predict a series of $D_{3h}\text{−}n$ states under mild tensile strains. With such atomistic Hamiltonians, the microscopic origins of different CDW states are revealed as the competition of the second-nearest neighbor V-V pairs versus the first-nearest neighbor V-V and V-Sb couplings. Interestingly, the effective Hamiltonians also reveal the existence of ionic Dzyaloshinskii-Moriya interaction in the high-symmetry phase of ${\mathrm{CsV}}_3{\mathrm{Sb}}_5$ and drives the formation of noncollinear CDW patterns. Our work thus not only deepens the understanding of the CDW formation in ${\mathrm{AV}}_3{\mathrm{Sb}}_5$, but also demonstrates that the effective Hamiltonian is a suitable approach for investigating CDW mechanisms, which can be extended to various CDW systems.

Building large-scale superconducting quantum circuits will require miniaturization and integration of supporting devices including microwave circulators, which are currently bulky, stand-alone components. Here, we report the measurement of microwave scattering from a ring of Josephson junctions, with dc-only control fields. We detect the effect of quasiparticle tunneling, and dynamically classify the system at its operating design point into different quasiparticle sectors. We optimize the device within one of the quasiparticle sectors, where we observe an unambiguous signature of nonreciprocal 3-port scattering within that sector. This enables operation as a circulator, and at the optimal circulation point, we observe on-resonance insertion loss of 2 dB, isolation of 14 dB, power reflectance of $-11\mathrm{dB}$, and a bandwidth of 200 MHz, averaged over the 3 input ports.

Spontaneous phase separation, or demixing, is important in biological phenomena such as cell sorting. In particle-based models, an open question is whether differences in diffusivity can drive such demixing. While differential-diffusivity-induced phase separation occurs in mixtures with a packing fraction up to 0.7 [S. N. Weber et al. Binary mixtures of particles with different diffusivities demix, Phys. Rev. Lett. 116, 058301 (2016)], here we investigate whether demixing persists at even higher densities relevant for cells. For particle packing fractions between 0.7 and 1.0 the system demixes, but at packing fractions above unity the system remains mixed, exposing re-entrant behavior in the phase diagram that occurs when phase separation can no longer drive a change in entropy production at high densities. We also find that a confluent Voronoi model for tissues does not phase separate, consistent with particle-based simulations.

If dark matter is ultralight, the number density of dark matter is very high, and the techniques of zero-temperature field theory are no longer valid. The dark matter number density modifies the vacuum, giving it a non-negligible particle occupation number. For fermionic dark matter, this occupation number can be no larger than one. However, in the case of bosons, the occupation number is unbounded. If there is a large occupation number, the Bose enhancement needs to be taken into consideration for any process involving particles which interact with the dark matter. Because the occupation number scales inversely with the dark matter mass, this effect is most prominent for ultralight dark matter. In fact, the Bose enhancement effect from the background is so significant for ultralight dark matter that, if dark matter is a dark photon, the correction to the anomalous magnetic moment is larger than experimental uncertainties for a mixing parameter of the order of ${10}^{-16}$ and a dark photon mass of the order of ${10}^{-20}\mathrm{eV}$. Furthermore, the constraint on the mixing parameter scales linearly with the dark photon mass, and so new significant constraints can be placed on the dark matter mass all the way up to ${10}^{-14}\mathrm{eV}$. Future experiments measuring $g-2$ will probe even smaller gauge mixing parameters.

By analyzing $7.33{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ annihilation data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, we report the observation of the semileptonic decay $D_s^{+}\to {\eta }^{\prime }{\mu }^{+}{\nu }_{\mu }$, with a statistical significance larger than $10\sigma$, and the measurements of the $D_s^{+}\to \eta {\mu }^{+}{\nu }_{\mu }$ and $D_s^{+}\to {\eta }^{\prime }{\mu }^{+}{\nu }_{\mu }$ decay dynamics for the first time. The branching fractions of $D_s^{+}\to \eta {\mu }^{+}{\nu }_{\mu }$ and $D_s^{+}\to {\eta }^{\prime }{\mu }^{+}{\nu }_{\mu }$ are determined to be $(2.235\pm 0.051_{\mathrm{stat}}\pm 0.052_{\mathrm{syst}})\%$ and $(0.801\pm 0.055_{\mathrm{stat}}\pm 0.028_{\mathrm{syst}})\%$, respectively, with precision improved by factors of 6.0 and 6.6 compared to the previous best measurements. Combined with the results for the decays $D_s^{+}\to \eta e^{+}{\nu }_e$ and $D_s^{+}\to {\eta }^{\prime }{e}^{+}{\nu }_e$, the ratios of the decay widths are examined both inclusively and in several ${\ell }^{+}{\nu }_{\ell }$ four-momentum transfer ranges. No evidence for lepton flavor universality violation is found within the current statistics. The products of the hadronic form factors $f_{+,0}^{{\eta }^{(\prime )}}(0)$ and the $c\to s$ Cabibbo-Kobayashi-Maskawa matrix element $|V_{cs}|$ are determined. The results based on the two-parameter series expansion are $f_{+,0}^{\eta }(0)|V_{cs}|=0.452\pm 0.010_{\mathrm{stat}}\pm 0.007_{\mathrm{syst}}$ and $f_{+,0}^{{\eta }^{\prime }}(0)|V_{cs}|=0.504\pm 0.037_{\mathrm{stat}}\pm 0.012_{\mathrm{syst}}$, which help to constrain present models on $f_{+,0}^{{\eta }^{(\prime )}}(0)$. The forward-backward asymmetries are determined to be $⟨A_{\mathrm{FB}}^{\eta }⟩=-0.059\pm 0.031_{\mathrm{stat}}\pm 0.005_{\mathrm{syst}}$ and $⟨A_{\mathrm{FB}}^{{\eta }^{\prime }}⟩=-0.064\pm 0.079_{\mathrm{stat}}\pm 0.006_{\mathrm{syst}}$ for the first time, which are consistent with the theoretical calculation.

Working to all orders in dimensionally regularized QCD with massless quarks, we study the radiation of a photon whose energy is much lower than that of external partons. The conventional soft photon theorem receives corrections at leading power in the photon energy, associated with soft virtual loops of massless fermions. These additive corrections give an overall factor times the nonradiative amplitude that is infrared finite and real to all orders in ${\alpha }_s$. Based on recent calculations of the three-loop soft gluon current, we identify the lowest-order three-loop correction.

With the aim of studying nonperturbative out-of-equilibrium dynamics of high-energy particle collisions on quantum simulators, we investigate the scattering dynamics of lattice quantum electrodynamics in $1+1$ dimensions. Working in the bosonized formulation of the model and in the thermodynamic limit, we use uniform-matrix-product-state tensor networks to construct multiparticle wave-packet states, evolve them in time, and detect outgoing particles post collision. This facilitates the numerical simulation of scattering experiments in both confined and deconfined regimes of the model at different energies, giving rise to rich phenomenology, including inelastic production of quark and meson states, meson disintegration, and dynamical string formation and breaking. We obtain elastic and inelastic scattering cross sections, together with time-resolved momentum and position distributions of the outgoing particles. Furthermore, we propose an analog circuit-QED implementation of the scattering process that is native to the platform, requires minimal ingredients and approximations, and enables practical schemes for particle wave-packet preparation and evolution. This study highlights the role of classical and quantum simulation in enhancing our understanding of scattering processes in quantum field theories in real time.

Three $\mathrm{\Delta }I=1$ bands with the $\pi g_{9/2}\otimes \nu g_{9/2}$ configuration have been identified in ${}_{35}{}^{74}{\mathrm{Br}}_{39}$. Angular distribution, linear polarization, and lifetime measurements were performed to determine the multipolarity, type, mixing ratio, and absolute transition probability of the transitions. By comparing these experimental observations with the corresponding fingerprints and the quantum particle rotor model calculations, the second and third lowest bands are, respectively, suggested as the chiral partner and one-phonon wobbling excitation built on the yrast band. The evidence indicates the first chiral wobbler in nuclei.

We show that a modulated longitudinal cavity-qubit coupling can be used to control the path taken by a multiphoton coherent-state wave packet conditioned on the state of a qubit, resulting in a qubit–which-path (QWP) entangled state. QWP states can generate long-range multipartite entanglement using strategies for interfacing discrete- and continuous-variable degrees of freedom. Using the approach presented here, entanglement can be distributed in a quantum network without the need for single-photon sources or detectors.

We report the existence of dissipationless currents in bilayer superconductors above the critical temperature $T_c$, assuming that the superconducting phase transition is dominated by phase fluctuations. Using a semiclassical U(1) lattice gauge theory, we show that thermal fluctuations cause a transition from the superconducting state at low temperature to a resistive state above $T_c$, accompanied by the proliferation of unbound vortices. Remarkably, while the proliferation of vortex excitations causes dissipation of homogeneous in-plane currents, we find that counterflow currents, flowing in the opposite direction within a bilayer, remain dissipationless. The presence of a dissipationless current channel above $T_c$ is attributed to the inhibition of vortex motion by local superconducting coherence within a single bilayer, in the presence of counterflow currents. Our theory presents a possible scenario for the pseudogap phase in bilayer cuprates.