Nature Physics最新文献

Tissues eliminate unfit, unwanted or unnecessary cells through cell extrusion, and this can lead to the elimination of both apoptotic and live cells. However, the mechanical signatures that influence the fate of extruding cells remain unknown. Here we show that modified force transmission across adherens junctions inhibits apoptotic cell eliminations. By combining cell experiments with varying levels of E-cadherin junctions and three-dimensional modelling of cell monolayers, we find that these changes not only affect the fate of the extruded cells but also shift extrusion from the apical to the basal side, leading to cell invasion into soft collagen gels. We generalize our findings using xenografts and cysts cultured in matrigel, derived from patients with breast cancer. Our results link intercellular force transmission regulated by cell–cell communication to cell extrusion mechanisms, with potential implications during morphogenesis and invasion of cancer cells.

Particle-like topological structures such as polar skyrmions in ferroelectrics have the potential for application in high-density information storage. Since the polar topologies arise from a complicated competitive energy balance, such non-trivial topological states are difficult to manipulate by applying non-persistent external stimuli, such as bias or strain. Thus, a flexible strategy for manipulating topological polar states is needed to realize ultrahigh-density topological devices. Here we demonstrate that thermal excitation can simultaneously regulate the competition of elastic, electrostatic, polarization gradient and Landau energies to trigger polar topological state switching. By designing the temperature evolution pathways, the individual states that are believed to be unstable or intermediate can now be switched and stabilized. Therefore, our strategy expands the diversity of polar topologies in a single superlattice system. Furthermore, we demonstrate the laser-based thermal local switching of polar solitons ranging from several hundred nanometres to a few topologies. These findings will advance the design of polar topology-based ultrahigh-density storage.

The intrinsic anomalous Hall effect (AHE) is driven by non-zero Berry curvature and spontaneous time-reversal symmetry breaking. This effect can be realized in two-dimensional moiré systems hosting flat electronic bands but is not usually seen in inversion-symmetric materials. Here, we show that this physics is manifested in helical trilayer graphene—three graphene layers, each twisted in sequence by the same angle—although the system retains global in-plane inversion symmetry. We uncover a phase diagram of correlated and magnetic states at a magic twist angle of 1.8^∘, which is explained by a lattice relaxation that leads to the formation of large periodic domains where in-plane inversion symmetry is broken on the moiré scale. Each domain harbours flat topological bands with opposite Chern numbers in the two valleys. We find correlated states at multiple integer and fractional electron fillings per moiré unit cell and an AHE at a subset of them. The AHE disappears above a critical electric displacement field at one electron per unit cell, indicating a topological phase transition. We establish helical trilayer graphene as a platform that presents an opportunity to engineer topology due to its emergent moiré-scale symmetries.

Malignancies of epithelial tissues, called carcinomas, account for most cancer cases. Research has largely focused on correlating different carcinoma subtypes to genetic alterations. However, as well as a rewiring in the signalling networks, carcinoma progression is accompanied by mechanical changes in the epithelial cells and the extracellular matrix. Here we reveal intricate morphologies in the basement membrane at the onset of bladder cancer and propose that they emerge from a mechanical instability upon epithelial overgrowth. We imaged mouse and human bladder tissue and performed differential growth simulations, and found that stiffness changes in the different mucosa layers can result in aberrant tissue morphologies. The resulting thickening, wrinkles and folds resemble early papillary tumours and carcinomas in situ. Atomic force microscopy confirmed local stiffness changes in the pathological basement membrane. Our findings suggest a possible mechanical origin of the different bladder carcinoma subtypes and may guide future developments in treatment and prophylaxis.

Reducing decoherence in quantum computers rapidly decreases the overhead needed to construct a logical qubit from physical qubits. In solid-state systems, a class of defects known as two-level systems is a major source of decoherence. Currently, superconducting qubit experiments reduce dissipation due to the two-level systems by using large device dimensions. However, this approach only provides partial protection and results in a trade-off between qubit size and dissipation. In this work, we instead engineer the interactions between a qubit and the surrounding two-level systems using phononics. We fabricate a superconducting qubit on a phononic-bandgap metamaterial that suppresses phonon emission mediated by the two-level systems. The phonon-engineered bath of two-level systems shows increased lifetime and affects the thermalization dynamics of the qubit. Within the phononic bandgap, we observe the emergence of a non-Markovian qubit behaviour. Combined with qubit miniaturization, our approach could substantially extend the qubit relaxation times.

Superionic materials represent a regime intermediate between the crystalline and liquid states of matter. Despite the considerable interest in potential applications for solid-state batteries or thermoelectric devices, it remains unclear whether the fast ionic diffusion observed in superionic materials reflects liquid-like dynamics or whether the hops of mobile ions are inherently coupled to more conventional lattice phonons. Here we reveal a crossover from crystalline vibrations to relaxational dynamics of ionic diffusion in the superionic compound Li₆PS₅Cl, a candidate solid-state electrolyte. By combining inelastic and quasi-elastic neutron-scattering measurements with first-principles-based machine-learned molecular dynamics simulations, we found that the vibrational density of states in the superionic state strongly deviates from the quadratic behaviour expected from the Debye law of lattice dynamics. The superionic dynamics emerges from overdamped phonon quasiparticles to give rise to a linear density of states characteristic of instantaneous normal modes in the liquid state. Further, we showed that the coupling of lattice phonons with a dynamic breathing of the Li⁺ diffusion bottleneck enables an order-of-magnitude increase in diffusivity. Thus, our results shed insights into superionics for future energy storage and conversion technologies.

The most efficient and promising operational regime for the International Thermonuclear Experimental Reactor tokamak is the high-confinement mode. In this regime, however, periodic relaxations of the plasma edge can occur. These edge-localized modes pose a threat to the integrity of the fusion device. Here we reveal the strong impact of energetic ions on the spatio-temporal structure of edge-localized modes in tokamaks using nonlinear hybrid kinetic–magnetohydrodynamic simulations. A resonant interaction between the fast ions at the plasma edge and the electromagnetic perturbations from the edge-localized mode leads to an energy and momentum exchange. Energetic ions modify, for example, the amplitude, frequency spectrum and crash timing of edge-localized modes. The simulations reproduce some observations that feature abrupt and large edge-localized mode crashes. The results indicate that, in the International Thermonuclear Experimental Reactor, a strong interaction between the fusion-born alpha particles and ions from neutral beam injection, a main heating and fast particle source, is expected with predicted edge-localized mode perturbations. This work advances the understanding of the physics underlying edge-localized mode crashes in the presence of energetic particles and highlights the importance of including energetic ion kinetic effects in the optimization of edge-localized mode control techniques and regimes that are free of such modes.

Continuous quantum phase transitions are widely assumed and frequently observed in various systems of quantum particles or spins. Their characteristic trait is a second-order, gradual suppression of the order parameter as the quantum critical point is approached. The localization of Cooper pairs in disordered superconductors and the resulting breakdown of superconductivity have long stood as a prototypical example. Here we show a departure from this paradigm, in which a discontinuous first-order quantum phase transition is tuned by disorder. We measure the plasmon spectrum in superconducting microwave resonators on amorphous superconducting films of indium oxide to provide evidence for a marked jump in both the zero-temperature superfluid stiffness and the transition temperature at the critical disorder. This discontinuous transition sheds light on the role of repulsive interactions between Cooper pairs and the subsequent competition between superconductivity and insulating Cooper-pair glass. Furthermore, we show that the critical temperature of the films no longer relates to the pairing amplitude but aligns with the superfluid stiffness, consistent with the pseudogap regime of preformed Cooper pairs. Our findings raise fundamental new questions about the role of disorder in quantum phase transitions and carry implications for superinductances in quantum circuits.