Simulation of chemical reaction dynamics based on quantum computing

The molecular energies of chemical systems have been successfully calculated on quantum computers, however, more attention has been paid to the dynamic process of chemical reactions in practical application, especially in catalyst design, material synthesis. Due to the limited the capabilities of the noisy intermediate scale quantum (NISQ) devices, directly simulating the reaction dynamics and determining reaction pathway still remain a challenge. Here we develop the ab initio molecular dynamics based on quantum computing to simulate reaction dynamics by extending correlated sampling approach. And, we use this approach to calculate Hessian matrix and evaluate computation resources. We test the performance of our approach by simulating hydrogen exchange reaction and bimolecular nucleophilic substitution SN2 reaction. Our results suggest that it is reliable to characterize the molecular structure, property, and reactivity, which is another important expansion of the application of quantum computingComment: 8 pages, 4 figure

Variational quantum eigensolver with linear depth problem-inspired ansatz for solving portfolio optimization in finance

Great efforts have been dedicated in recent years to explore practical applications for noisy intermediate-scale quantum (NISQ) computers, which is a fundamental and challenging problem in quantum computing. As one of the most promising methods, the variational quantum eigensolver (VQE) has been extensively studied. In this paper, VQE is applied to solve portfolio optimization problems in finance by designing two hardware-efficient Dicke state ansatze that reach a maximum of 2n two-qubit gate depth and n^2/4 parameters, with n being the number of qubits used. Both ansatze are partitioning-friendly, allowing for the proposal of a highly scalable quantum/classical hybrid distributed computing (HDC) scheme. Combining simultaneous sampling, problem-specific measurement error mitigation, and fragment reuse techniques, we successfully implement the HDC experiments on the superconducting quantum computer Wu Kong with up to 55 qubits. The simulation and experimental results illustrate that the restricted expressibility of the ansatze, induced by the small number of parameters and limited entanglement, is advantageous for solving classical optimization problems with the cost function of the conditional value-at-risk (CVaR) for the NISQ era and beyond. Furthermore, the HDC scheme shows great potential for achieving quantum advantage in the NISQ era. We hope that the heuristic idea presented in this paper can motivate fruitful investigations in current and future quantum computing paradigms.Comment: 21 pages, 20 figure

Research on Climate Change and Water Heritage Tourism Based on the Adaptation Theory—A Case Study of the Grand Canal (Beijing Section)

Water is at the forefront of climate change and is seen as a major channel through which the effects of climate change are felt. The function of water heritage is closely related to the water bodies on which it depends. Under climate change, the conservation and tourism uses of water heritage resources are facing impacts and challenges. Taking the Beijing Section of the Grand Canal of China as a case, this research applied the adaptation theory to explore the impacts of climate change on heritage tourism of the section of the Grand Canal in Beijing. It was identified that changes in the temperature and the precipitation formed climate-related stimuli to tourism along the Canal from 2012 to 2021 in Beijing. Second, from the supply side of tourism, policies were formulated at a national or municipal level to respond to the changing climate and its impacts on the Canal and its tourism uses. Natural-based solutions (NbS) have been applied to rehabilitate the ecosystem of the Canal, contributing to the enhanced tourism landscape, and providing opportunities for ecological education. Third, from the demand side, high tourism participation along the Canal was examined during the high-temperature years. Meanwhile, the increasing tourist needs for water spaces and activities were observed with evident seasonal patterns. Accordingly, suggestions for climate adaptation of the Grand Canal from a tourism perspective were proposed. For heritage conservation, actions of ecological restoration and monitoring should be further implemented. To assist in the climate adaptation and sustainable development of Grand Canal tourism, suggestions are proposed to enhance the overall tourism planning, increase water accessibility, and heritage interpretation for tourists

Predicting RNA Secondary Structure on Universal Quantum Computer

It is the first step for understanding how RNA structure folds from base sequences that to know how its secondary structure is formed. Traditional energy-based algorithms are short of precision, particularly for non-nested sequences, while learning-based algorithms face challenges in obtaining high-quality training data. Recently, quantum annealer has rapidly predicted the folding of the secondary structure, highlighting that quantum computing is a promising solution to this problem. However, gate model algorithms for universal quantum computing are not available. In this paper, gate-based quantum algorithms will be presented, which are highly flexible and can be applied to various physical devices. Mapped all possible secondary structure to the state of a quadratic Hamiltonian, the whole folding process is described as a quadratic unconstrained binary optimization model. Then the model can be solved through quantum approximation optimization algorithm. We demonstrate the performance with both numerical simulation and experimental realization. Throughout our benchmark dataset, simulation results suggest that our quantum approach is comparable in accuracy to classical methods. For non-nested sequences, our quantum approach outperforms classical energy-based methods. Experimental results also indicate our method is robust in current noisy devices. It is the first instance of universal quantum algorithms being employed to tackle RNA folding problems, and our work provides a valuable model for utilizing universal quantum computers in solving RNA folding problems.Comment: 19 pages, 7 figure