We simulate ultra-cold interacting bosons in quasi-one-dimensional, incommensurate optical lattices. In the tight-binding limit, these lattices have pseudo-random on-site energies and thus can potentially lead to Ande...We simulate ultra-cold interacting bosons in quasi-one-dimensional, incommensurate optical lattices. In the tight-binding limit, these lattices have pseudo-random on-site energies and thus can potentially lead to Anderson localization. We use the Hartree-Fock-Bogoliubov formalism in the Bose-Hubbard model to explore the parameter regimes that lead to exponential localization of the ground state in a 3-colour optical lattice and investigate the role of repulsive interactions, harmonic confinement and finite temperature.展开更多
Ultra-cold atoms provide ideal platforms for interferometry.The macroscopic matter-wave property of ultra-cold atoms leads to large coherent length and long coherent time,which enable high accuracy and sensitivity to ...Ultra-cold atoms provide ideal platforms for interferometry.The macroscopic matter-wave property of ultra-cold atoms leads to large coherent length and long coherent time,which enable high accuracy and sensitivity to measurement.Here,we review our efforts to improve the performance of the interferometer.We demonstrate a shortcut method for manipulating ultra-cold atoms in an optical lattice.Compared with traditional ones,this shortcut method can reduce the manipulation time by up to three orders of magnitude.We construct a matter-wave Ramsey interferometer for trapped motional quantum states and significantly increase its coherence time by one order of magnitude with an echo technique based on this method.Efforts have also been made to enhance the resolution by multimode scheme.Application of a noise-resilient multi-component interferometer shows that increasing the number of paths could sharpen the peaks in the time-domain interference fringes,which leads to a resolution nearly twice compared with that of a conventional double-path two-mode interferometer.With the shortcut method mentioned above,improvement of the momentum resolution could also be fulfilled,which leads to atomic momentum patterns less than 0.6hkL. To identify and remove systematic noises,we introduce the methods based on the principal component analysis (PCA) that reduce the noise in detection close to the 1/√2 of the photon-shot noise and separate and identify or even eliminate noises.Furthermore,we give a proposal to measure precisely the local gravity acceleration within a few centimeters based on our study of ultracold atoms in precision measurements.展开更多
在全球能源危机与环境保护意识日益增强的背景下,超低能耗建筑暖通空调(heating,ventilation and air conditioning,HVAC)系统能效的提升尤为重要。基于此,文章探讨了冷水温度控制的基本原理及其对建筑能耗的影响,并通过实时监测和数据...在全球能源危机与环境保护意识日益增强的背景下,超低能耗建筑暖通空调(heating,ventilation and air conditioning,HVAC)系统能效的提升尤为重要。基于此,文章探讨了冷水温度控制的基本原理及其对建筑能耗的影响,并通过实时监测和数据分析,结合建筑使用特性与外部气候因素,提出了通过智能化、自动化的控制策略实现冷水温度优化控制的方法,以有效提高室内环境的舒适度并降低能耗。文章仿真分析结果表明,优化控制方法在冷水温度调节速度和水泵能耗方面均优于现有文献方法,为超低能耗建筑HVAC系统冷水温度优化控制提供了有效方案。展开更多
基金supported by contract SFB/TR 12 of the German Research Foundation and through the IB BMBF(Project NZL 07/006)by the New Zealand Foundation for Research,Science and Technology through contract NERF-UOOX0703:Quantum Technologies and the New Zealand International Science and Technology Linkages FundJT and DAWH also acknowledge support from the National Research Foundation and Ministry of Education of Singapor.
文摘We simulate ultra-cold interacting bosons in quasi-one-dimensional, incommensurate optical lattices. In the tight-binding limit, these lattices have pseudo-random on-site energies and thus can potentially lead to Anderson localization. We use the Hartree-Fock-Bogoliubov formalism in the Bose-Hubbard model to explore the parameter regimes that lead to exponential localization of the ground state in a 3-colour optical lattice and investigate the role of repulsive interactions, harmonic confinement and finite temperature.
基金Project supported by the National Basic Research Program of China(Grant No.2016YFA0301501)the National Natural Science Foundation of China(Grant Nos.61727819,11934002,91736208,and 11920101004)the Project funded by China Postdoctoral Science Foundation(Grant No.2020TQ0017)。
文摘Ultra-cold atoms provide ideal platforms for interferometry.The macroscopic matter-wave property of ultra-cold atoms leads to large coherent length and long coherent time,which enable high accuracy and sensitivity to measurement.Here,we review our efforts to improve the performance of the interferometer.We demonstrate a shortcut method for manipulating ultra-cold atoms in an optical lattice.Compared with traditional ones,this shortcut method can reduce the manipulation time by up to three orders of magnitude.We construct a matter-wave Ramsey interferometer for trapped motional quantum states and significantly increase its coherence time by one order of magnitude with an echo technique based on this method.Efforts have also been made to enhance the resolution by multimode scheme.Application of a noise-resilient multi-component interferometer shows that increasing the number of paths could sharpen the peaks in the time-domain interference fringes,which leads to a resolution nearly twice compared with that of a conventional double-path two-mode interferometer.With the shortcut method mentioned above,improvement of the momentum resolution could also be fulfilled,which leads to atomic momentum patterns less than 0.6hkL. To identify and remove systematic noises,we introduce the methods based on the principal component analysis (PCA) that reduce the noise in detection close to the 1/√2 of the photon-shot noise and separate and identify or even eliminate noises.Furthermore,we give a proposal to measure precisely the local gravity acceleration within a few centimeters based on our study of ultracold atoms in precision measurements.
文摘在全球能源危机与环境保护意识日益增强的背景下,超低能耗建筑暖通空调(heating,ventilation and air conditioning,HVAC)系统能效的提升尤为重要。基于此,文章探讨了冷水温度控制的基本原理及其对建筑能耗的影响,并通过实时监测和数据分析,结合建筑使用特性与外部气候因素,提出了通过智能化、自动化的控制策略实现冷水温度优化控制的方法,以有效提高室内环境的舒适度并降低能耗。文章仿真分析结果表明,优化控制方法在冷水温度调节速度和水泵能耗方面均优于现有文献方法,为超低能耗建筑HVAC系统冷水温度优化控制提供了有效方案。
