Topological phonon blockade and its transfer via dark-mode engineering.

Unidirectional topological behavior, engendered by imposing topological operations winding around an exceptional point, is sensitive to dark modes, which allow deactivating topological operations, resulting in a complete blockade of both mode conversion and phonon transfer between dark and bright modes. Here we demonstrate how to beat this challenge and achieve a versatile yet unique nonreciprocal topological phonon transfer and blockade via dark-mode engineering. This happens by harnessing the power of synthetic magnetism, leading to an extraordinary transition between the dark-mode nonbreaking and breaking regimes, in a precise and controlled manner.

Chemistry beyond the scale of exact diagonalization on a quantum-centric supercomputer.

A universal quantum computer can simulate diverse quantum systems, with electronic structure for chemistry offering challenging problems for practical use cases around the hundred-qubit mark. Although current quantum processors have reached this size, deep circuits and a large number of measurements lead to prohibitive runtimes for quantum computers in isolation. Here, we demonstrate the use of classical distributed computing to offload all but an intrinsically quantum component of a workflow for electronic structure simulations.

Provably Efficient Simulation of 1D Long-Range Interacting Systems at Any Temperature.

We introduce a method that ensures efficient computation of one-dimensional quantum systems with long-range interactions across all temperatures. Our algorithm operates within a quasipolynomial run-time for inverse temperatures up to β=poly(ln(n)). At the core of our approach is the density matrix renormalization group algorithm, which typically does not guarantee efficiency.

Topological Quantum Batteries.

We propose an innovative design for quantum batteries (QBs) that involves coupling two-level systems to a topological photonic waveguide. Employing the resolvent method, we analytically explore the thermodynamic performance of QBs. First, we demonstrate that in the long-time limit, only bound states significantly contribute to the stored energy of QBs.

Nonlinear Optical Response in Kagome Lattice with Inversion Symmetry Breaking.

The kagome lattice is a fundamental model structure in condensed matter physics and materials science featuring symmetry-protected flat bands, saddle points, and Dirac points. This structure has emerged as an ideal platform for exploring various quantum physics. By combining effective model analysis and first-principles calculations, we propose that the synergy among inversion symmetry breaking, flat bands, and saddle point-related van Hove singularities within the kagome lattice holds significant potential for generating the strong second-order nonlinear optical response.

Effects of hydroxypropyl starch on intestinal health and transcriptome of geese.

In recent years, gout resulting from uric acid metabolism disorders has led to significant economic losses in goose production. The intestine is a vital organ crucial for uric acid metabolism. Hydroxypropyl starch (HPS) is a resistant starch modified from natural starch, which can enhance intestinal health as a dietary ingredient fiber.

Research on Quantum Materials and Quantum Technology at RIKEN.

RIKEN covers fundamental research on physics, chemistry, biology, life and medical science, information and mathematical science, and engineering. Here, we outline research activities on quantum materials and quantum technology that include topological and correlated materials, spintronics, nanoscale materials and structures, atomic and quantum optics, and quantum computing.

Computable Entanglement Cost under Positive Partial Transpose Operations.

Quantum information theory is plagued by the problem of regularizations, which require the evaluation of formidable asymptotic quantities. This makes it computationally intractable to gain a precise quantitative understanding of the ultimate efficiency of key operational tasks such as entanglement manipulation. Here, we consider the problem of computing the asymptotic entanglement cost of preparing noisy quantum states under quantum operations with positive partial transpose (PPT).

Recent advances in dynamic single-molecule analysis platforms for diagnostics: Advantages over bulk assays and miniaturization approaches.

Single-molecule science is a unique technique for unraveling molecular biophysical processes. Sensitivity to single molecules provides the capacity for the early diagnosis of low biomarker amounts. Furthermore, the miniaturization of instruments for portable diagnostic tools toward point-of-care testing (POCT) is a crucial development in this field.

Thermal Area Law in Long-Range Interacting Systems.

The area law of the bipartite information measure characterizes one of the most fundamental aspects of quantum many-body physics. In thermal equilibrium, the area law for the mutual information universally holds at arbitrary temperatures as long as the systems have short-range interactions. In systems with power-law decaying interactions, r^{-α} (r: distance), conditions for the thermal area law are elusive.

Entangling Schrödinger's cat states by bridging discrete- and continuous-variable encoding.

In quantum information processing, two primary research directions have emerged: one based on discrete variables (DV) and the other on the structure of quantum states in a continuous-variable (CV) space. Integrating these two approaches could unlock new potentials, overcoming their respective limitations. Here, we show that such a DV-CV hybrid approach, applied to superconducting Kerr parametric oscillators (KPOs), enables us to entangle a pair of Schrödinger's cat states by two methods.

Distillable entanglement under dually non-entangling operations.

Computing the exact rate at which entanglement can be distilled from noisy quantum states is one of the longest-standing questions in quantum information. We give an exact solution for entanglement distillation under the set of dually non-entangling (DNE) operations-a relaxation of the typically considered local operations and classical communication, comprising all channels which preserve the sets of separable states and measurements. We show that the DNE distillable entanglement coincides with a modified version of the regularised relative entropy of entanglement in which the arguments are measured with a separable measurement.

Causal Classification of Spatiotemporal Quantum Correlations.

From correlations in measurement outcomes alone, can two otherwise isolated parties establish whether such correlations are atemporal? That is, can they rule out that they have been given the same system at two different times? Classical statistics says no, yet quantum theory disagrees. Here, we introduce the necessary and sufficient conditions by which such quantum correlations can be identified as atemporal. We demonstrate the asymmetry of atemporality under time reversal and reveal it to be a measure of spatial quantum correlation distinct from entanglement.

High-performance fault-tolerant quantum computing with many-hypercube codes.

Standard approaches to quantum error correction for fault-tolerant quantum computing are based on encoding a single logical qubit into many physical ones, resulting in asymptotically zero encoding rates and therefore huge resource overheads. To overcome this issue, high-rate quantum codes, such as quantum low-density parity-check codes, have been studied over the past decade. In this case, however, it is difficult to perform logical gates in parallel while maintaining low overheads.

Demonstration of microwave single-shot quantum key distribution.

Security of modern classical data encryption often relies on computationally hard problems, which can be trivialized with the advent of quantum computers. A potential remedy for this is quantum communication which takes advantage of the laws of quantum physics to provide secure exchange of information. Here, quantum key distribution (QKD) represents a powerful tool, allowing for unconditionally secure quantum communication between remote parties.

Experimental Search for Invisible Dark Matter Axions around 22  μeV.

The axion has emerged as the most attractive solution to two fundamental questions in modern physics related to the charge-parity invariance in strong interactions and the invisible matter component of our Universe. Over the past decade, there have been many theoretical efforts to constrain the axion mass based on various cosmological assumptions. Interestingly, different approaches from independent groups produce good overlap between 20 and 30  μeV.

Reversibility of quantum resources through probabilistic protocols.

Among the most fundamental questions in the manipulation of quantum resources such as entanglement is the possibility of reversibly transforming all resource states. The key consequence of this would be the identification of a unique entropic resource measure that exactly quantifies the limits of achievable transformation rates. Remarkably, previous results claimed that such asymptotic reversibility holds true in very general settings; however, recently those findings have been found to be incomplete, casting doubt on the conjecture.

Water-Wave Vortices and Skyrmions.

Topological wave structures-phase vortices, skyrmions, merons, etc.-are attracting enormous attention in a variety of quantum and classical wave fields. Surprisingly, these structures have never been properly explored in the most obvious example of classical waves: water-surface (gravity-capillary) waves.

Virtual Quantum Resource Distillation.

Distillation, or purification, is central to the practical use of quantum resources in noisy settings often encountered in quantum communication and computation. Conventionally, distillation requires using some restricted "free" operations to convert a noisy state into one that approximates a desired pure state. Here, we propose to relax this setting by only requiring the approximation of the measurement statistics of a target pure state, which allows for additional classical postprocessing of the measurement outcomes.

Observation and manipulation of quantum interference in a superconducting Kerr parametric oscillator.

Quantum tunneling is the phenomenon that makes superconducting circuits "quantum". Recently, there has been a renewed interest in using quantum tunneling in phase space of a Kerr parametric oscillator as a resource for quantum information processing. Here, we report a direct observation of quantum interference induced by such tunneling and its dynamics in a planar superconducting circuit through Wigner tomography.

Probing the symmetry breaking of a light-matter system by an ancillary qubit.

Hybrid quantum systems in the ultrastrong, and even more in the deep-strong, coupling regimes can exhibit exotic physical phenomena and promise new applications in quantum technologies. In these nonperturbative regimes, a qubit-resonator system has an entangled quantum vacuum with a nonzero average photon number in the resonator, where the photons are virtual and cannot be directly detected. The vacuum field, however, is able to induce the symmetry breaking of a dispersively coupled probe qubit.