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Abstract Fractional quantum Hall (FQH) states are exotic quantum many-body phases whose elementary charged excitations are anyons obeying fractional braiding statistics. While most FQH states are believed to have Abelian anyons, the Moore–Read type states with even denominators – appearing at half filling of a Landau level (LL) – are predicted to possess non-Abelian excitations with appealing potential in topological quantum computation. These states, however, depend sensitively on the orbital contents of the single-particle LL wavefunctions and the LL mixing. Here we report magnetotransport measurements on Bernal-stacked trilayer graphene, whose multiband structure facilitates interlaced LL mixing, which can be controlled by external magnetic and displacement fields. We observe robust FQH states including even-denominator ones at filling factors ν = − 9/2, − 3/2, 3/2 and 9/2. In addition, we fine-tune the LL mixing and crossings to drive quantum phase transitions of these half-filling states and neighbouring odd-denominator ones, exhibiting related emerging and waning behaviour.

Abstract Topological materials with boundary (surface/edge/hinge) states have attracted tremendous research interest. Additionally, unconventional (obstructed atomic) materials have recently drawn lots of attention owing to their obstructed boundary states. Experimentally, Josephson junctions (JJs) constructed on materials with boundary states produce the peculiar boundary supercurrent, which was utilized as a powerful diagnostic approach. Here, we report the observations of boundary supercurrent in NiTe2-based JJs. Particularly, applying an in-plane magnetic field along the Josephson current can rapidly suppress the bulk supercurrent and retain the nearly pure boundary supercurrent, namely the magnetic field filtering of supercurrent. Further systematic comparative analysis and theoretical calculations demonstrate the existence of unconventional nature and obstructed hinge states in NiTe2, which could produce hinge supercurrent that accounts for the observation. Our results reveal the probable hinge states in unconventional metal NiTe2, and demonstrate in-plane magnetic field as an efficient method to filter out the bulk contributions and thereby to highlight the hinge states hidden in topological/unconventional materials.

Abstract Coherence and tunneling play central roles in quantum phenomena. In a tunneling event, the time that a particle spends inside the barrier has been fiercely debated. This problem becomes more complex when tunneling repeatedly occurs back and forth, and when involving many particles. Here we report the measurement of the coherence time of various charge states tunneling in a nanowire-based tunable Josephson junction; including single charges, multiple charges, and Cooper pairs. We studied all the charge tunneling processes using Landau-Zener-Stückelberg-Majorana (LZSM) interferometry, and observed high-quality interference patterns under a microwave drive. In particular, the coherence time of the charge states tunneling back and forth was extracted from the interference fringes in Fourier space. In addition, our measurements show the break-up of Cooper pairs, from a macroscopic quantum coherent state to individual particle states. Besides the fundamental research interest, our results also establish LZSM interferometry as a powerful technique to explore the coherence time of charges in hybrid devices.

Abstract The interplay between topology and interaction always plays an important role in condensed matter physics and induces many exotic quantum phases, while rare transition metal layered material (TMLM) has been proved to possess both. Here we report a TMLM Ta2Pd3Te5 has the two-dimensional second-order topology (also a quadrupole topological insulator) with correlated edge states - Luttinger liquid. It is ascribed to the unconventional nature of the mismatch between charge- and atomic- centers induced by a remarkable double-band inversion. This one-dimensional protected edge state preserves the Luttinger liquid behavior with robustness and universality in scale from micro- to macro- size, leading to a significant anisotropic electrical transport through two-dimensional sides of bulk materials. Moreover, the bulk gap can be modulated by the thickness, resulting in an extensive-range phase diagram for Luttinger liquid. These provide an attractive model to study the interaction and quantum phases in correlated topological systems.

Abstract We demonstrate that superconducting gatemon qubits based on superconductor-semiconductor-superconductor Josephson junctions can be constructed on hole-type Ge/Si core/shell nanowires. The frequency of the qubit can be set firstly by controlling the diffusion of Al in the nanowire via thermal annealing, which yields a suitable critical supercurrent allowing the qubit frequency to be within the experimentally accessible range, and then by fine tuning of a gate voltage, by which an accurate adjustment of the frequency can be realized. On the resulted qubit, Rabi oscillation with an energy relaxation time $${T}_{1} \sim 180\,{\rm{ns}}$$ T 1 ~ 180 ns was observed in the time domain, an average decoherence time $${T}_{2}^{* } \sim 15\,{\rm{ns}}$$ T 2 * ~ 15 ns was obtained, and the gate voltage dependence of both $${T}_{1}$$ T 1 and $${T}_{2}^{* }$$ T 2 * was investigated. Such a hole-type superconducting gatemon qubit, based on materials with strong spin-orbit coupling and potentially the absence of hyperfine interaction after isotope purification, could be used for exploring the quantum coherence phenomena of hole-gas and even Majorana physics in Ge-based quantum devices.

Two-dimensional transition metal dichalcogenides with peculiar spin–orbit coupling may lead to exotic phenomena. Here, the authors report a large in-plane upper critical field with a two-fold symmetry, suggesting a novel asymmetric spin–orbit coupling in few-layer 1T d-MoTe2.

Two-dimensional superconductors will likely have applications not only in devices, but also in the study of fundamental physics. Here, Wang et al. demonstrate the CVD growth of superconducting NbSe2 on a variety of substrates, making these novel materials increasingly accessible.

Heavy fermion materials: evidence for a quasi-one-dimensional Kondo lattice Evidence is provided for a heavy fermion material that is an unusual example of a quasi-one-dimensional Kondo lattice system. Heavy fermion materials are compounds with localised magnetic moments that interact strongly with the surrounding conduction electrons, causing a rich variety of exotic behaviour to arise. And when these moments form a periodic array, a Kondo lattice can be formed —where scattering off the moments becomes coherent. An international team of researchers led by Yi-feng Yang and Youguo Shi from the Institute of Physics, Chinese Academy of Sciences now present an unusual example of a Kondo lattice system that is quasi-one-dimensional in nature. Using a combination of experiments and first-principles calculations they show that the cerium atoms in single crystals of CeCo2Ga8 form chains, leading to quasi-one-dimensional Kondo lattice behaviour and unusual quantum critical scalings that are not expected in the conventional quantum critical theory.