Quantum information processing enhances human's power to simulate nature in quantum level and solve complex problem efficiently. During the process, a series of operators is performed to evolve the ...system or undertake a computing task. In recent year, research interest in non-Hermitian quantum systems, dissipative-quantum systems and new quantum algorithms has greatly increased, which nonunitary operators take an important role in. In this work, we utilize the linear combination of unitaries technique for nonunitary dynamics on a single qubit to give explicit decompositions of the necessary unitaries, and simulate arbitrary time-dependent single-qubit nonunitary operator F(t) using duality quantum algorithm. We find that the successful probability is not only decided by F(t) and the initial state, but also is inversely proportional to the dimensions of the used ancillary Hilbert subspace. In a general case, the simulation can be achieved in both eight- and six-dimensional Hilbert spaces. In phase matching conditions, F(t) can be simulated by only two qubits. We illustrate our method by simulating typical non-Hermitian systems and single-qubit measurements. Our method can be extended to high-dimensional case, such as Abrams-Lloyd's two-qubit gate. By discussing the practicability, we expect applications and experimental implementations in the near future.
Some patients with positive chest CT findings may present with negative results of real-time reverse-transcription polymerase chain reaction (RT-PCR) tests for coronavirus disease 2019 (COVID-19). In ...this study, the authors present chest CT findings from five patients with COVID-19 infection who had initial negative RT-PCR results. All five patients had typical imaging findings, including ground-glass opacity (five patients) and/or mixed ground-glass opacity and mixed consolidation (two patients). After isolation for presumed COVID-19 pneumonia, all patients were eventually confirmed to have COVID-19 infection by means of repeated swab tests. A combination of repeated swab tests and CT scanning may be helpful for individuals with a high clinical suspicion of COVID-19 infection but negative findings at RT-PCR screening.
Organic afterglow materials, developed recently by breaking through the difficulties in modulating ultrafast‐decayed excited states, exhibit ultralong‐lived emission for persistent luminescence with ...lifetimes of several orders of magnitude longer than traditional fluorescent and phosphorescent emissions at room temperature. Their exceptional properties, namely ultralong luminescent lifetime, large Stokes shifts, facile excited state transformation, and environmentally sensitive emission, have led to a diverse range of advanced optoelectronic applications. Here, the organic afterglow is reviewed from the perspective of fundamental concepts on both phenomenon and mechanism, examining the technical challenges in relation to excited state tuning and lifetime elongation. In particular, the advances in material design strategies that afford a large variety of organic afterglow materials for a broad utility in optoelectronics including lighting and displays, anti‐counterfeiting, optical recording, chemical sensors and bio‐imaging are highlighted.
Organic afterglow with persistent room‐temperature phosphorescence (lifetime > 0.1 s) has revolutionized current understanding of organic luminescence, exhibiting promising potential in a wide range of optoelectronic applications. Recent advances in the development of organic afterglow materials are summarized, extracting fundamental principles from excited state manipulation strategies, organic afterglow phenomena and characterizations, material constructions, and device applications.
In this paper, we first consider one of the interconnected enterprises in the economy as nodes in a complex network. Based on the SIRS risk contagion model, we describe the transmission process of ...credit risk between enterprises after the bursting of the stock market with the contagion process, and clarify their diffusion mechanism and effect. The propagation effect of SIRS model in complex network is simulated and analyzed. The results show that when the risk contagion intensity exceeds a certain threshold and the proportion of infected enterprises in the economy exceeds a certain level, it will inevitably lead to the insecurity of the whole economy. In most cases, the policy intervention of the regulatory authorities is necessary. If the crisis is allowed to infect, it is likely to induce the financial risk of the whole system; The construction of smart city credit system can use big data to solve the problem of information island, promote the co construction and sharing of data resources, assist the regulators to effectively prevent and block the transmission of credit risk, and nip the risk in the bud, so as to maintain social stability and economic security.
Non-Hermitian (NH) quantum theory has been attracting increased research interest due to its featured properties, novel phenomena, and links to open and dissipative systems. Typical NH systems ...include PT-symmetric systems, pseudo-Hermitian systems, and their anti-symmetric counterparts. In this work, we generalize the pseudo-Hermitian systems to their complex counterparts, which we call pseudo-Hermitian-φ-symmetric systems. This complex extension adds an extra degree of freedom to the original symmetry. On the one hand, it enlarges the non-Hermitian class relevant to pseudo-Hermiticity. On the other hand, the conventional pseudo-Hermitian systems can be understood better as a subgroup of this wider class. The well-defined inner product and pseudo-inner product are still valid. Since quantum simulation provides a strong method to investigate NH systems, we mainly investigate how to simulate this novel system in a Hermitian system using the linear combination of unitaries in the scheme of duality quantum computing. We illustrate in detail how to simulate a general P-pseudo-Hermitian-φ-symmetric two-level system. Duality quantum algorithms have been recently successfully applied to similar types of simulations, so we look forward to the implementation of available quantum devices.
Herein, the first acceptorless dehydrogenation of tetrahydroquinolines (THQs), indolines, and other related N‐heterocycles, by merging visible‐light photoredox catalysis and cobalt catalysis at ...ambient temperature, is described. The potential applications to organic transformations and hydrogen‐storage materials are demonstrated. Primary mechanistic investigations indicate that the catalytic cycle occurs predominantly by an oxidative quenching pathway.
Cobalt and blue: The titled method is utilized for the reversible dehydrogenation‐hydrogenation protocol at ambient temperature under mild reaction conditions. Primary mechanistic investigations indicate that the catalytic cycle relies predominantly on an oxidative quenching pathway.
Operation optimization for modern subway trains usually requires the speed curve optimization and speed curve tracking simultaneously. For the speed curve optimization, a multi-objective seeking ...issue should be addressed by considering the requirements of energy saving, punctuality, accurate parking, and comfortableness at the same time. But most traditional searching methods lack in efficiency or tend to fall into the local optimum. For the speed curve tracking, the widely applied proportional integral differential (PID) and fuzzy controllers rely on complicated parameter tuning, whereas robust adaptive methods can hardly ensure the finite-time convergence strictly, and thus are not suitable for applications in fixed time intervals of trains. To address the above-mentioned two problems, this paper presents a novel approach for speed curve seeking and tracking control. First, we present the random reinforcement genetic algorithm (GA) algorithm to avoid the local optimum efficiently. Then, a sliding mode controller is developed for speed curve tracking with bounded disturbance. The Lyapunov theory is adopted to prove that the system can be stabilized in the finite time. Finally, using the real datasets of Yizhuang Line in Beijing Subway, the proposed approach is validated, demonstrating its effectiveness and superiorities for the operation optimization.
Instability of perovskite photovoltaics is still a topic that is currently under intense debate, especially the role of the water environment. Unraveling the mechanism of this instability is urgent ...to enable practical application of perovskite solar cells. Here, ab initio metadynamics is employed to investigate the initial phase of a dissolution process of CH3NH3PbI3 (MAPbI3) in explicit water. It is found that the initial dissolution of MAPbI3 is a complex multistep process triggered by the departure of I– ion from the CH3NH3I-terminated surface. Reconstruction of the free-energy landscape indicates a low energy barrier for water dissolution of MAPbI3. In addition, we propose a two-step thermodynamic cycle for MAPbI3 dissolution in water at a finite concentration that renders spontaneity to the dissolution process. The low energy barrier for the initial dissolution step and the spontaneous nature of MAPbI3 dissolution in water explain why water immediately destroys pristine MAPbI3. The dissolution thermodynamics of all-inorganic CsPbI3 perovskite is also analyzed for comparison. Hydration enthalpies and entropies of aqueous ions play an important role for the dissolution process. Our findings provide a comprehensive understanding to the current debate on water instability of MAPbI3.
The ubiquitin‐proteasome system (UPS) is a complex process that regulates protein stability and activity by the sequential actions of E1, E2 and E3 enzymes to influence diverse aspects of eukaryotic ...cells. However, due to the diversity of proteins in cells, substrate selection is a highly critical part of the process. As a key player in UPS, E3 ubiquitin ligases recruit substrates for ubiquitination specifically. Among them, RING E3 ubiquitin ligases which are the most abundant E3 ubiquitin ligases contribute to diverse cellular processes. The multisubunit cullin‐RING ligases (CRLs) are the largest family of RING E3 ubiquitin ligases with tremendous plasticity in substrate specificity and regulate a vast array of cellular functions. The F‐box protein Skp2 is a component of CRL1 (the prototype of CRLs) which is expressed in many tissues and participates in multiple cellular functions such as cell proliferation, metabolism, and tumorigenesis by contributing to the ubiquitination and subsequent degradation of several specific tumor suppressors. Most importantly, Skp2 plays a pivotal role in a plethora of cancer‐associated signaling pathways. It enhances cell growth, accelerates cell cycle progression, promotes migration and invasion, and inhibits cell apoptosis among others. Hence, targeting Skp2 may represent a novel and attractive strategy for the treatment of different human cancers overexpressing this oncogene. In this review article, we summarized the known roles of Skp2 both in health and disease states in relation to the UPS.
In the modern financial system, division of labor and close cooperation between different departments are determinants of risk contagion. The risk resulting from the volatility of the stock market ...can easily spread to other industries and departments, leading to systemic financial and economic crises. Previous research has mostly examined financial security from the lens of macro currency security, and the security of the banking system, but has ignored its micro-basic problems, such as the bounded rationality of investors due to the lack of financial knowledge. The study analyzes the behavior of micro-investors, price fluctuations in the meso‑stock market, and the macro-financial security in a unified framework. First, we use the comprehensive analysis method to superimpose some basic values and investor behavior characteristics, such as the stock price fluctuation index, and then construct the ultimate stock price bubble index; second, the principal component method is used to establish a financial security index that is in line with basic economic reality and consistent with previous studies; the innovative MS-VAR model is used to analyze whether the stock price bubble will affect financial security, and the rhythm and correlation of the two parties under different regimes are summarized. The results show that the stock market bubble level is the Granger cause of financial security, the stock market bubble index is the leading indicator of the financial security index, and the relevant parameters of the model are significant and have obvious economic significance. This study has important implications for scientific market regulation.
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