Journal: Nature Physics

Abbreviation

Nat. Phys.

Publisher

Nature

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ISSN

1745-2473
1745-2481

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Publications 1 - 10 of 171
  • Correlations, indistinguishability and entanglement in Hong-Ou-Mandel experiments at microwave frequencies
    Item type: Journal Article
    Lang, C.; Eichler, C.; Steffen, L.; et al. (2013)
    Nature Physics
  • Emergent seesaw oscillations during cellular directional decision-making
    Item type: Journal Article
    Ron, Jonathan E.; Crestani, Michele; Kux, Johan M.; et al. (2024)
    Nature Physics
    Motile cells inside living tissues often encounter junctions, where their path branches into several alternative directions of migration. We present a theoretical model of cellular polarization for a cell migrating along a one-dimensional line, arriving at a symmetric Y junction and extending protrusions along the different paths that originate at the junction. The model predicts the spontaneous emergence of deterministic oscillations of growth and cellular polarization between competing protrusions during the directional decision-making process. The oscillations are modified by cellular noise but remain a dominant feature that affects the time it takes the cell to migrate across the junction. These predictions are confirmed experimentally for two different cell types (non-cancerous endothelial and cancerous glioma cells) migrating on a patterned network of thin adhesive lanes with junctions.
  • Cyclic jetting enables microbubble-mediated drug delivery
    Item type: Journal Article
    Cattaneo, Marco; Guerriero, Giulia; Shakya, Gazendra; et al. (2025)
    Nature Physics
    The pursuit of targeted therapies capable of overcoming biological barriers, including the blood-brain barrier, has spurred the investigation of stimuli-responsive microagents that can improve therapeutic efficacy and reduce undesirable side effects. Intravenously administered, ultrasound-responsive microbubbles are promising agents with demonstrated potential in clinical trials, but the mechanism underlying drug absorption remains unclear. Here we show that ultrasound-driven single microbubbles puncture the cell membrane and induce drug uptake through stable cyclic microjets. Our theoretical models successfully reproduce the observed bubble and cell dynamic responses. We find that cyclic jets arise from shape instabilities, as opposed to classical inertial jets that are driven by pressure gradients, enabling microjet formation at mild ultrasound pressures below 100 kPa. We also establish a threshold for bubble radial expansion beyond which microjets form and facilitate cellular permeation and show that the stress generated by microjetting outperforms previously suggested mechanisms by at least an order of magnitude. Overall, this work elucidates the physics behind microbubble-mediated targeted drug delivery and provides the criteria for its effective and safe application.
  • Long-lived valley states in bilayer graphene quantum dots
    Item type: Journal Article
    Garreis, Rebekka; Tong, Chuyao; Terle, Jocelyn; et al. (2024)
    Nature Physics
    Bilayer graphene is a promising platform for electrically controllable qubits in a two-dimensional material. Of particular interest is the ability to encode quantum information in the valley degree of freedom, a two-fold orbital degeneracy that arises from the symmetry of the hexagonal crystal structure. The use of valleys could be advantageous, as known spin- and orbital-mixing mechanisms are unlikely to be at work for valleys, promising more robust qubits. The Berry curvature associated with valley states allows for electrical control of their energies, suggesting routes for coherent qubit manipulation. However, the relaxation time of valley states—which ultimately limits these qubits’ coherence properties and therefore their suitability as practical qubits—is not yet known. Here we measure the characteristic relaxation times of these spin and valley states in gate-defined bilayer graphene quantum dot devices. Different valley states can be distinguished from each other with a fidelity of over 99%. The relaxation time between valley triplets and singlets exceeds 500 ms and is more than one order of magnitude longer than for spin states. This work facilitates future measurements on valley-qubit coherence, demonstrating bilayer graphene as a practical platform hosting electrically controlled, long-lived valley qubits.
  • Control of spin currents by magnon interference in a canted antiferromagnet
    Item type: Journal Article
    Sheng, Lutong; Duvakina, Anna; Wang, Hanchen; et al. (2025)
    Nature Physics
    Controlling the spin current lies at the heart of spintronics and its applications. In ferromagnets, the sign of spin currents is fixed once the current direction is determined. However, spin currents in antiferromagnets can possess opposite polarizations, but this requires enormous magnetic fields to lift the degeneracy between the two modes. Therefore, controlling spin currents with opposite polarization is still a challenge. Here we demonstrate the control of spin currents at room temperature by magnon interference in a canted antiferromagnet, namely, haematite that has recently been classified as an altermagnet. Magneto-optical characterization by Brillouin light scattering reveals that the spatial periodicity of the beating patterns is tunable via the microwave frequency. We further observe that the inverse spin Hall voltage changes sign as the frequency is tuned, evincing a frequency-controlled switching of polarization of pure spin currents. Our work highlights the use of antiferromagnetic magnon interference to control spin currents, which substantially extends the horizon for the emerging field of coherent antiferromagnetic spintronics.
  • Verification of the area law of mutual information in a quantum field simulator
    Item type: Journal Article
    Tajik, Mohammadamin; Kukuljan, Ivan; Sotiriadis, Spyros; et al. (2023)
    Nature Physics
    The theoretical understanding of scaling laws of entropies and mutual information has led to substantial advances in the study of correlated states of matter, quantum field theory and gravity. Experimentally measuring von Neumann entropy in quantum many-body systems is challenging, as it requires complete knowledge of the density matrix, which normally requires the implementation of full state reconstruction techniques. Here we measure the von Neumann entropy of spatially extended subsystems in an ultracold atom simulator of one-dimensional quantum field theories. We experimentally verify one of the fundamental properties of equilibrium states of gapped quantum many-body systems-the area law of quantum mutual information. We also study the dependence of mutual information on temperature and on the separation between the subsystems. Our work represents a step towards employing ultracold atom simulators to probe entanglement in quantum field theories.
  • Hydrodynamics: Modus vivendi
    Item type: Journal Article
    Fernandez, Vicente I.; Stocker, Roman (2017)
    Nature Physics
  • Attosecond circular-dichroism chronoscopy of electron vortices
    Item type: Journal Article
    Han, Meng; Ji, Jia-Bao; Balčiūnas, Tadas; et al. (2023)
    Nature Physics
    Circular dichroism (CD) describes the different responses of a chiral object to circularly polarized light of opposite handedness and serves as the basis of most chirality-sensitive spectroscopy techniques. All previously observed CD effects originate from the chiral sensitivity of the amplitudes of transition-matrix elements. However, CD effects in the phase of such matrix elements have barely been studied, even theoretically. Here we present a combined experimental and theoretical investigation of amplitude- and phase-resolved CDs of continuum-continuum transitions for electron vortices. We employ a circularly polarized attosecond pulse train to prepare electron vortices in the continuum, and a circularly polarized near-infrared laser pulse to probe the chirality of the electron vortices. Our complete experimental reconstruction of the partial-wave amplitudes and phases demonstrates that the photoionization time delays of the continuum-continuum transitions depend not only on the angular-momentum quantum number l of the populated continuum state, but also on its magnetic quantum number m. Our work defines a general technique called attosecond circular-dichroism chronoscopy (ACDC), which can provide new insights into electron-vortex beams, chiral molecules and magnetic materials on the most fundamental timescales.
  • Switching of magnetic domains reveals spatially inhomogeneous superconductivity
    Item type: Journal Article
    Gerber, Simon; Bartkowiak, Marek; Gavilano, Jorge L.; et al. (2014)
    Nature Physics
  • Chemotaxis under flow disorder shapes microbial dispersion in porous media
    Item type: Journal Article
    de Anna, Pietro; Pahlavan, Amir A.; Yawata, Yutaka; et al. (2021)
    Nature Physics
    Bacteria live in heterogeneous environments, so it is important to investigate their behaviour in porous media. Here the authors show that flow disorder enhances the effect of chemical gradients in micropockets in a porous medium, which then aid the transport of bacteria. Natural soils are host to a high density(1)and diversity(2)of microorganisms, and even deep-earth porous rocks provide a habitat for active microbial communities(3). In these environments, microbial transport by disordered flows is relevant for a broad range of natural and engineered processes, from biochemical cycling to remineralization and bioremediation(4-7). Yet, how bacteria are transported and distributed in the subsurface as a result of the disordered flow and the associated chemical gradients characteristic of porous media has remained poorly understood, in part because studies have so far focused on steady, macroscale chemical gradients(8-10). Here, we use a microfluidic model system that captures flow disorder and chemical gradients at the pore scale to quantify the transport and dispersion of the soil-dwelling bacteriumBacillus subtilisin porous media. We observe that chemotaxis strongly modulates the persistence of bacteria in low-flow regions of the pore space, resulting in a 100% increase in their dispersion coefficient. This effect stems directly from the strong pore-scale gradients created by flow disorder and demonstrates that the microscale interplay between bacterial behaviour and pore-scale disorder can impact the macroscale dynamics of biota in the subsurface.
Publications 1 - 10 of 171