Quantum computers must operate in concert with classical computers to deliver on the promise of quantum advantage for practical problems. To achieve that, it is important to understand how quantum and classical computing can interact together, and how one can characterize the scalability and efficiency of hybrid quantum–classical workflows. So far, early experiments with quantum-centric supercomputing workflows have been limited in scale and complexity. Here, we use a Heron quantum processor deployed on premises with the entire supercomputer Fugaku to perform the largest computation of electronic structure involving quantum and classical high-performance computing. We design a closed-loop workflow between the quantum processors and 152,064 classical nodes of Fugaku, to approximate the electronic structure of chemistry models beyond the reach of exact diagonalization, with accuracy comparable to some all-classical approximation methods. Our work pushes the limits of the integration of quantum and classical high-performance computing, showcasing computational resource orchestration at the largest scale possible for current classical supercomputers.
QuTiP, the Quantum Toolbox in Python, has been at the forefront of open-source quantum software for the last ten years. It is used as a research, teaching, and industrial tool, and has been downloaded millions of times by users around the world. Here we introduce the latest developments in QuTiP v5, which are set to have a large impact on the future of QuTiP and enable it to be a modern, continuously developed and popular tool for another decade and more. We summarize the code design and fundamental data layer changes as well as efficiency improvements, new solvers, applications to quantum circuits with QuTiP-QIP, and new quantum control tools with QuTiP-QOC. Additional flexibility in the data layer underlying all "quantum objects" in QuTiP allows us to harness the power of state-of-the-art data formats and packages like JAX, CuPy, and more. We explain these new features with a series of both well-known and new examples. The code for these examples is available in a static form on GitHub and will be available also in a continuously updated and documented notebook form in the qutip-tutorials package.
Stellar coronae exhibit diverse properties across different stellar environments. However, the underlying physics that governs this diversity remains incompletely understood. In this review, we summarize recent theoretical and observational efforts to characterize coronae under various stellar conditions, with a particular focus on the role of metallicity in coronal heating. We present scaling laws for coronal loops that explicitly incorporate metallicity dependence, extending conventional models of coronal structure. To evaluate these theoretical predictions, we perform one-dimensional magnetohydrodynamic (MHD) simulations of coronal loops, which account for dynamic processes such as wave propagation, shock dissipation, and turbulent heating. The simulations reveal that lower-metallicity environments lead to higher coronal densities and temperatures due to reduced radiative cooling efficiencies. We compare the simulation results with our scaling relations and with observational data from stellar X-ray studies. The overall agreement supports the validity of the metallicity-dependent model and helps to explain previous observations of bright, metal-poor coronae.
LSSmOrange is a fluorescent protein that exhibits slow photoconversion and is used as an imaging tool to highlight specific subpopulations of molecules. While photoconversion in LSSmOrange is known to involve Kolbe decarboxylation of the E215 side chain, its structural dynamics remain unexplored. We addressed the excited state dynamics of LSSmOrange by using serial femtosecond crystallography (SFX) with an X-ray free electron laser. SFX enabled us to determine the crystal structure of unconverted LSSmOrange without detectable X-ray damage, facilitating a femtosecond optical pumpX-ray probe experiment to track time-resolved structural changes. A decrease in electron density at E215 was observed 250 ps after strong pump laser illumination (mean fluence of 0.31 J/cm2), consistent with photoconversion by decarboxylation. Extrapolated structures suggested the appearance of an alternative E215 conformation in addition to illumination-induced decarboxylation. Since the photoinduced decarboxylation occurred despite the extremely low single-photon photoconversion quantum yield of LSSmOrange (8.5 × 10-6), we hypothesized that the photoconversion proceeds via a multiphoton process. Power titration using transient absorption spectroscopy revealed that photoconversion was linked to optical nonlinearity under a high pump laser energy. We propose that LSSmOrange photoconversion involves a higher-lying electronic excited state triggered by multiphoton absorption, as supported by quantum-chemical calculations. Photoconversion via a multiphoton process enables spatially confined highlighting on a microscope.
