We propose a novel type of skin effects in non-Hermitian quantum many-body systems that we dub a “non-Hermitian Mott skin effect.” This phenomenon is induced by the interplay between strong correlations and the non-Hermitian point-gap topology. The Mott skin effect induces extreme sensitivity to the boundary conditions only in the spin degree of freedom (i.e., the charge distribution is not sensitive to boundary conditions), which is in sharp contrast to the ordinary non-Hermitian skin effect in noninteracting systems. Concretely, we elucidate that a bosonic non-Hermitian chain exhibits the Mott skin effect in the strongly correlated regime by closely examining an effective Hamiltonian. The emergence of the Mott skin effect is also supported by numerical diagonalization of the bosonic chain. The difference between the ordinary non-Hermitian skin effect and the Mott skin effect is also reflected in the time evolution of physical quantities; under the time evolution spin accumulation is observed while the charge distribution remains spatially uniform.

Entanglement propagation provides a key routine to understand quantum many-body dynamics in and out of equilibrium. Entanglement entropy (EE) usually approaches to a subsaturation known as the Page value ${\tilde{S}}_P=\tilde{S}-dS$ (with $\tilde{S}$ the maximum of EE and $dS$ the Page correction) in, e.g., the random unitary evolutions. The ballistic spreading of EE usually appears in the early time and will be deviated far before the Page value is reached. In this work, we uncover that the magnetic field that maximizes the EE robustly induces persistent ballistic spreading of entanglement in quantum spin chains. The linear growth of EE is demonstrated to persist until the maximal $\tilde{S}$ (along with a flat entanglement spectrum) is reached. The robustness of ballistic spreading and the enhancement of EE under such an optimal control are demonstrated, considering particularly perturbing the initial state by random pure states (RPSs). These are argued as the results from the endomorphism of the time evolution under such an entanglement-enhancing optimal control for the RPSs.

A key question in the thermodynamics of open quantum systems is how to partition thermodynamic quantities such as entropy, work, and internal energy between the system and its environment. We show that the only partition under which entropy is nonsingular is based on a partition of Hilbert space, which assigns half the system-environment coupling to the system and half to the environment. However, quantum work partitions nontrivially under Hilbert-space partition, and we derive a work sum rule that accounts for quantum work at a distance. All state functions of the system are shown to be path independent once this nonlocal quantum work is properly accounted for. Our results are illustrated with application to a driven resonant level strongly coupled to a reservoir.

Millicharged particles appear in several extensions of the standard model, but have not yet been detected. These hypothetical particles could be produced by an intense proton beam striking a fixed target. We use data collected in 2020 by the SENSEI experiment in the MINOS cavern at the Fermi National Accelerator Laboratory to search for ultrarelativistic millicharged particles produced in collisions of protons in the NuMI beam with a fixed graphite target. The absence of any ionization events with 3 to 6 electrons in the SENSEI data allow us to place world-leading constraints on millicharged particles for masses between 30 to 380 MeV. This work also demonstrates the potential of utilizing low-threshold detectors to investigate new particles in beam-dump experiments, and motivates a future experiment designed specifically for this purpose.

Modern hydrodynamic simulations of core-collapse supernovae and neutron-star mergers require knowledge not only of the equilibrium properties of strongly interacting matter, but also of the system’s response to perturbations, encoded in various transport coefficients. Using perturbative and holographic tools, we derive here an improved weak-coupling and a new strong-coupling result for the most important transport coefficient of unpaired quark matter, its bulk viscosity. These results are combined in a simple analytic pocket formula for the quantity that is rooted in perturbative quantum chromodynamics at high densities but takes into account nonperturbative holographic input at neutron-star densities, where the system is strongly coupled. This expression can be used in the modeling of unpaired quark matter at astrophysically relevant temperatures and densities.

Isomer spectroscopy of heavy neutron-rich nuclei beyond the $N=126$ closed shell has been performed for the first time at the Radioactive Isotope Beam Factory of the RIKEN Nishina Center. New millisecond isomers have been identified at low excitation energies, 985.3(19) keV in ${}^{213}\mathrm{Tl}$ and 874(5) keV in ${}^{215}\mathrm{Tl}$. The measured half-lives of 1.34(5) ms in ${}^{213}\mathrm{Tl}$ and 3.0(3) ms in ${}^{215}\mathrm{Tl}$ suggest spins and parities $11/2^{-}$ with the single proton-hole configuration $\pi h_{11/2}$ as leading component. They are populated via $E1$ transitions by the decay of higher-lying isomeric states with proposed spin and parity $17/2^{+}$, interpreted as arising from a single $\pi s_{1/2}$ proton hole coupled to the $8^{+}$ seniority isomer in the ${}^{A+1}\mathrm{Pb}$ cores. The lowering of the $11/2^{-}$ states is ascribed to an increase of the $\pi h_{11/2}$ proton effective single-particle energy as the second $\nu g_{9/2}$ orbital is filled by neutrons, owing to a significant reduction of the proton-neutron monopole interaction between the $\pi h_{11/2}$ and $\nu g_{9/2}$ orbitals. The new $ms$ isomers provide the first experimental observation of shell evolution in the almost unexplored $N>126$ nuclear region below doubly magic ${}^{208}\mathrm{Pb}$.

Excited states in ${}^{10}\mathrm{B}$ were populated with the ${}^{10}\mathrm{B}(p,p^{\prime }\gamma ){{}^{10}\mathrm{B}}^{*}$ reaction at 8.5 MeV and their $\gamma$ decay was investigated via coincidence $\gamma$-ray spectroscopy. The emitted $\gamma$ rays were measured using large-volume ${\mathrm{LaBr}}_3:\mathrm{Ce}$ and ${\mathrm{CeBr}}_3$ detectors placed in anti-Compton shields. This allowed the observation of weak $\gamma$-ray transitions, such as the $M3$ transition between the $J^{\pi },T=0^{+},1$ isobaric analog state (IAS) and the $J^{\pi },T=3^{+},0$ ground state and the $E2$ transition between the $J^{\pi },T=2_1^{+},0$ state and the IAS, i.e., performing measurements of branching ratios at the level of $\lambda \ge {10}^{-4}$. For the first time in ${}^{10}\mathrm{B}$, the competing $M1$ and $M3$ transitions from the decay of the IAS have been observed in a $\gamma$ spectroscopy experiment. The experimental results are compared with ab initio no-core shell model calculation using the newest version of the local position-space chiral ${\mathrm{N}}^3\mathrm{LO}$ nucleon-nucleon interaction. The calculations reproduce correctly the ordering of the bound states in ${}^{10}\mathrm{B}$, and are in reasonable agreement with the observed branching ratios and reduced transition probabilities.

We investigate the photoionization dynamics of atoms subjected to intense, ultrashort laser pulses through the use of quantum trajectories. This method provides a unique and consistent framework for examining electron dynamics within a time-dependent potential barrier. Our findings demonstrate that quantum trajectories offer additional insights into several key aspects of strong-field ionization, including the transition between ionization regimes, nonadiabatic effects under the barrier, the impact of the shape of the electronic potential, and the efficiency of over-the-barrier ionization.

We investigate the fundamental viability of cooling ultracold atomic gases with quantum feedback control. Our Letter shows that the trade-off between the resolution and destructiveness of optical imaging techniques imposes constraints on the efficacy of feedback cooling, and that rapid rethermalization is necessary for cooling thermal gases. We construct a simple model to determine the limits to feedback cooling set by the visibility of density fluctuations, measurement-induced heating, and three-body atomic recombination. We demonstrate that feedback control can rapidly cool high-temperature thermal clouds in quasi-2D geometries to degenerate temperatures with minimal atom loss compared to traditional evaporation. Our analysis confirms the feasibility of feedback cooling ultracold atomic gases, providing a pathway to new regimes of cooling not achievable with current approaches.

Quantum-limited timing jitter of soliton microcombs has long been recognized as their fundamental noise limit. Here, we surpass such limit by utilizing dispersive wave dynamics in multimode microresonators. Through the viscous force provided by these dispersive waves, the quantum-limited timing jitter can be suppressed to a much lower level that forms the ultimate fundamental noise limit of soliton microcombs. Our findings enable coherence engineering of soliton microcombs in the quantum regime, providing critical guidelines for using soliton microcombs to synthesize ultralow-noise microwave and optical signals.

We present a data-driven method to learn stochastic reduced models of complex systems that retain a state-dependent memory beyond the standard generalized Langevin equation with a homogeneous kernel. The constructed model naturally encodes the heterogeneous energy dissipation by jointly learning a set of state features and the non-Markovian coupling among the features. Numerical results demonstrate the limitation of the standard generalized Langevin equation and the essential role of the broadly overlooked state-dependency nature in predicting molecule kinetics related to conformation relaxation and transition.

Quantum circuits utilizing measurement to evolve a quantum wave function offer a new and rich playground to engineer unconventional entanglement dynamics. Here, we introduce a hybrid, nonreciprocal setup featuring a quantum circuit, whose updates are conditioned on the state of a classical dynamical agent. In our example the circuit is represented by a Majorana quantum chain controlled by a classical $N$-state Potts chain undergoing pair flips. The local orientation of the classical spins controls whether randomly drawn local measurements on the quantum chain are allowed or not. This imposes a dynamical kinetic constraint on the entanglement growth, described by the transfer matrix of an $N$-colored loop model. It yields an equivalent description of the circuit by an $SU(N)$-symmetric Temperley-Lieb Hamiltonian or by a kinetically constrained surface growth model for an $N$-component height field. For $N=2$, we find a diffusive growth of the half-chain entanglement toward a stationary profile $S(L)\sim L^{1/2}$ for $L$ sites. For $N\ge 3$, the kinetic constraints impose Hilbert space fragmentation, yielding subdiffusive growth toward $S(L)\sim L^{0.57}$. This showcases how the control by a classical dynamical agent can enrich the entanglement dynamics in quantum circuits, paving a route toward novel entanglement dynamics in nonreciprocal hybrid circuit architectures.

In this Letter, we use quantum trajectory theory to simulate heterodyne detection of narrow bandwidth superradiant lasing from an incoherently excited atomic ensemble. To this end, we describe the system dynamics and account for stochastic measurement backaction by second-order mean-field theory. Our simulations show how heterodyne measurements break the phase symmetry, and initiate the atomic coherence with a random phase and a long temporal phase coherence. More importantly, our theory allows direct simulation of experimental procedures for extraction of spectral information which do not lend themselves to evaluation with the quantum regression theorem.