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  • Heralded fidelity-robust high-dimensional quantum computing
    In high-dimensional quantum systems, qudits offer a richer resource than traditional two-dimensional qubits, increasing the capacity of quantum channels and enhancing the efficiency of fault-tolerant quantum computation. These advantages can be utilized to solve complex problems across various fields. In the paper, we propose a 2-qudit controlled-NOT (CNOT) gate in a -dimensional space and a 3-qudit controlled-controlled-NOT (Toffoli) gate in a -dimensional space, both equipped with error-heralded units. Our designs do not require auxiliary photons or extra negatively charged nitrogen-vacancy (NV−) center, resulting in saving resources. Moreover, since the imperfect NV−-cavity interaction processes are predicted in real-time by sensitive single-photon detectors, both high-dimensional CNOT and Toffoli gates boast robust fidelities using existing technology. Furthermore, our protocols simplify circuits with error-heralded units, significantly contributing to the effectiveness of quantum information technology and paving the way for advanced high-dimensional quantum computing.

  • Physical interpretation of large Lorentz violation via Weyl semimetals
    The physical intepretation of effective field theories of fundamental interactions incorporating large Lorentz violation is a long-standing challenge, known as the concordance problem. In condensed-matter physics, certain Weyl semimetals with emergent Lorentz invariance exhibit large Lorentz violation, thereby offering prospective laboratory analogues for exploration of this issue. We take advantage of the mathematical equivalence between the descriptions of large Lorentz violation in fundamental and condensed-matter physics to investigate the primary aspects of the concordance problem, which arise when the coefficients for Lorentz violation are large or the observer frame is highly boosted. Using thermodynamic arguments, we present a physical solution to the concordance problem and explore some implications.

  • Exact solution of the relationship between the eigenvalue discreteness and the behavior of eigenstates in Su–Schrieffer–Heeger lattices
    The interplay between eigenvalue discreteness and eigenstate localization is a fundamental characteristic of one-dimensional Su–Schrieffer–Heeger (SSH) lattices. In this study, we investigate the relationship between the eigenvalue discreteness and the eigenstates behavior in 1D SSH lattices. The discreteness fraction (D) are introduced in combination with the inverse participation ratio to quantify this relationship. By employing the bulk-edge correspondence and perturbation theory, we derive an exact solution that accounts for both zero and non-zero modes. Our findings reveal a logarithmic relationship between the degree of eigenvalue discreteness and eigenstate localization in both the Hermitian and non-Hermitian conditions. This result provides a direct measure of edge-state localization strength in the topologically nontrivial phase.

  • Machine-learning certification of multipartite entanglement for noisy quantum hardware
    Entanglement is a fundamental aspect of quantum physics, both conceptually and for its many applications. Classifying an arbitrary multipartite state as entangled or separable—a task referred to as the separability problem—poses a significant challenge, since a state can be entangled with respect to many different of its partitions. We develop a certification pipeline that feeds the statistics of random local measurements into a non-linear dimensionality reduction algorithm, to determine with respect to which partitions a given quantum state is entangled. After training a model on randomly generated quantum states, entangled in different partitions and of varying purity, we verify the accuracy of its predictions on simulated test data, and finally apply it to states prepared on IBM quantum computing hardware.

  • Harnessing temporal dispersion for integrated pump filtering in spontaneous heralded single-photon generation processes
    Cointegration of heralded single-photon generation and on-chip detection requires the ability to differentiate between pump light and single photons. We explored the dispersion-induced temporal separation of optical pulses to reach this goal. Our method exploits the distinct group velocities of pump light and single photons, as well as single-photon detectors with high timing resolution. We simulate the propagation for photon pair generation by spontaneous parametric down-conversion in titanium in-diffused waveguides in lithium niobate and thin-film lithium niobate, and spontaneous four-wave mixing in silicon on insulator and silicon nitride. For the different integration platforms, we show the propagation distance required to sufficiently distinguish between pump and single photons for different timing resolutions, and demonstrate that this should be feasible with current superconducting nanowire single-photon detector technologies. Finally, we experimentally simulate our approach using the dispersion in the optical fiber.