Cavendish Hospital

Abstract As the diversity of exoplanets continues to grow, it is important to revisit assumptions about habitability and classical HZ definitions. In this work, we introduce an expanded ’temperate’ zone, defined by instellation fluxes between 0.1 < S/S⊕ < 5, thus encompassing a broader range of potentially habitable worlds. We also introduce the TEMPOS survey, which aims to produce a catalogue of precise radii for temperate planets orbiting M dwarfs with Teff ≤ 3400 K. This work reports the discovery and characterisation of two planets in this temperate regime orbiting mid-type M dwarfs: TOI-6716 b, a Rb = 0.98 ± 0.07 R⊕ planet orbiting its M4 host star (R⋆ = 0.231 ± 0.015R ⊙, M⋆ = 0.223 ± 0.011 M ⊙, Teff = 3110 ± 80 K) with a period $P=4.7185898^{+0.0000054}_{-0.0000041}\, \mathrm{d}$ , and TOI-7384 b, a Rb = 3.56 ± 0.21 R⊕ planet orbiting an M4 (R⋆ = 0.319 ± 0.018R ⊙, M⋆ = 0.318 ± 0.016 M ⊙, Teff = 3185 ± 75 K) star every $P=6.2340258^{+0.0000034}_{-0.0000036}\, \mathrm{d}$ . The radii of TOI-6716 b and TOI-7384 b have precisions of 6.8 % and 5.9 % respectively. We validate these planets with multi-band ground-based photometric observations, high-resolution imaging and statistical analyses. We find these planets to have instellation fluxes close to the inner (hotter) edge of the temperate zone, with Sb = 4.4 ± 1.1 S⊕ and Sb = 4.9 ± 1.1 S⊕ for TOI-6716 b and TOI-7384 b respectively. Also, with a predicted TSM similar to the TRAPPIST-1 planets, TOI-6716 b is likely to be a good rocky-world JWST target, should it have retained its atmosphere.

We uncover features of generalized contextuality by connecting it to the Kirkwood-Dirac (KD) quasiprobability distribution. Quantum states can be represented by KD distributions, which take values in the complex unit disk. Only for “KD-positive” states are the KD distributions joint probability distributions. A KD distribution can be measured by a series of weak and projective measurements. We design such an experiment and show that it is contextual iff the underlying state is not KD positive. We analyze this connection with respect to mixed KD-positive states that cannot be decomposed as convex combinations of pure KD-positive states. Our result is the construction of a noncontextual experiment that enables an experimenter to verify contextuality.

Abstract We report the discovery and characterization of three transiting giant planets in the TIC 118798035 system. The three planets were identified as transiting candidates from data of the TESS mission and confirmed with ground-based photometric transit observations along with radial velocity variations obtained with FEROS, HARPS, and ESPRESSO. The three planets present transit timing variations (TTVs). We performed an N -body orbital fitting to the TTVs and radial velocities, finding that TIC 118798035 b is a warm low-density Neptune with a mass of 0.0250 ± 0.0023 M J , a radius of 0.655 ± 0.018 R J , and an orbital period of 11.507 days; TIC 118798035 c is a warm Saturn with a mass of 0.403 ± 0.024 M J , a radius of 0.973 ± 0.023 R J , and an orbital period of 22.564 days; and TIC 118798035 d is a warm Jupiter with a mass of 0.773 ± 0.052 M J , a radius of 0.923 ± 0.044 R J , and an orbital period of 48.925 days. The bulk metallicities of the three planets do not fully follow the mass–metallicity correlation found for the giant planets of the solar system, which hints at a somewhat different formation history for the planets of the TIC 118798035 system.

We study optical manifestations of multigap band topology in multiband superconductors with a nontrivial topological Euler class. We introduce a set of lattice models for non-Abelian superconductors with the Euler invariant signified by a nontrivial quantum geometry. We then demonstrate that the topological Bogoliubov excitations realized in these models provide for a characteristic first-order optical response distinct from those of the other known topological superconductors. We find that the spectral distribution of the optical conductivity universally admits a topological jump originating from the Euler class in the presence of d-wave superconducting pairings and naturally differs from the features induced by the quantum geometry in the noninteracting bands without pairing terms. Further to uncovering observable signatures in first-order optical conductivities, we showcase that the higher-order optical responses of the non-Abelian Euler superconductor can result in enhanced nonlinear currents that fingerprint the exotic topological invariant. Finally, by employing a diagrammatic approach, we generalize our findings beyond the specific models of Euler superconductors.

We construct exact ground states of the J1−J3b classical Heisenberg model on the pyrochlore lattice in the presence of a magnetic field. They are noncoplanar multi-Q⃗ spin configurations with a large magnetic unit cell that generalize the previously found coplanar sublattice pairing states. Using linear spin-wave theory, we show that entropy favors these multi-Q⃗ states at low temperatures in high magnetic fields. This is confirmed by Monte Carlo simulations, and a phase diagram is constructed. We also calculate the zero-temperature dynamical structure factor. Besides the usual Goldstone modes associated with the ordering Q⃗s, we find high intensity gapless modes at momenta where there are no Bragg peaks. Published by the American Physical Society 2025

International audience

Hybrid organic–inorganic perovskite solar cells (PSCs) present a leading thin-film photovoltaic technology with superior solar-to-electric power conversion efficiencies. The most effective compositions, however, contain lead cations, which are toxic and pose environmental hazards. One of the alternatives to lead-based perovskite materials is silver bismuth halide analogues. Here, we present a comprehensive investigation of different silver bismuth iodide compositions by means of density functional theory calculations (DFT) as well as X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy measurements. Through our combined experimental and theoretical study, we have discovered that silver bismuth iodides possess several intrinsic limitations, such as limited charge transport and localized electronic states, owing to the presence of vacant sites. Such limitations result in moderate solar cell efficiencies, significantly lower than those of lead halide perovskites. However, we suggest the possibility of increasing efficiencies by adding BiCl3 to the precursor solution, yielding one of the highest efficiencies reported for this class of compounds to date. This highlights the potential of compositional engineering for these lead-free solar cell materials.

We analyze quantum-geometric bounds on optical weights in topological phases with pairs of bands hosting nontrivial Euler class, a multigap invariant characterizing non-Abelian band topology. We show how the bounds constrain the combined optical weights of the Euler bands at different dopings and further restrict the size of the adjacent band gaps. In this process, we also consider the associated interband contributions to dc conductivities in the flat-band limit. We physically validate these results by recasting the bound in terms of transition rates associated with the optical absorption of light, and demonstrate how the Euler connections and curvatures can be determined through the use of momentum and frequency-resolved optical measurements, allowing for a direct measurement of this multiband invariant. Additionally, we prove that the bound holds beyond the degenerate limit of Euler bands, resulting in nodal topology captured by the patch Euler class. In this context, we deduce optical manifestations of Euler topology within k·p models, which include quantized optical conductivity, and third-order jerk photoconductivities. We showcase our findings with numerical validation in lattice-regularized models that benchmark effective theories for real materials and are realizable in metamaterials and optical lattices.

We uncover new features of generalized contextuality by connecting it to the Kirkwood-Dirac (KD) quasiprobability distribution. Quantum states can be represented by KD distributions, which take values in the complex unit disc. Only for ``KD-positive'' states are the KD distributions joint probability distributions. A KD distribution can be measured by a series of weak and projective measurements. We design such an experiment and show that it is contextual iff the underlying state is not KD-positive. We analyze this connection with respect to mixed KD-positive states that cannot be decomposed as convex combinations of pure KD-positive states. Our result is the construction of a noncontextual experiment that enables an experimenter to verify contextuality.

ABSTRACT The AU Microscopii planetary system is only 24 Myr old, and its geometry may provide clues about the early dynamical history of planetary systems. Here, we present the first measurement of the Rossiter–McLaughlin effect for the warm sub-Neptune AU Mic c, using two transits observed simultaneously with the European Southern Observatory's (ESO's) Very Large Telescope (VLT)/Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO), CHaracterising ExOPlanet Satellite (CHEOPS), and Next-Generation Transit Survey (NGTS). After correcting for flares and for the magnetic activity of the host star, and accounting for transit-timing variations, we find the sky-projected spin–orbit angle of planet c to be in the range $\lambda _{\mathrm{c}}=67.8_{-49.0}^{+31.7}$ degrees (1$\sigma$). We examine the possibility that planet c is misaligned with respect to the orbit of the inner planet b ($\lambda _{\mathrm{b}}=-2.96_{-10.30}^{+10.44}$), and the equatorial plane of the host star, and discuss scenarios that could explain both this and the planet’s high density, including secular interactions with other bodies in the system or a giant impact. We note that a significantly misaligned orbit for planet c is in some degree of tension with the dynamical stability of the system, and with the fact that we see both planets in transit, though these arguments alone do not preclude such an orbit. Further observations would be highly desirable to constrain the spin–orbit angle of planet c more precisely.