基于双跃迁方法的温度鲁棒金刚石磁测量方法

作为一种具有良好发展前景的室温固态传感器,基于氮-空位(NV)色心的金刚石磁力计在近年来得到了巨大的发展,大量工作展示了其在实现高空间分辨率和高灵敏度方面的潜力。尽管如此,考虑到在大多数应用场景中通常难以避免温度漂移的影响,NV色心零场分裂D对温度的依赖性使得金刚石磁测量方法在实际应用中面临巨大的挑战。在本文中,我们展示了一种基于双跃迁方法的温度鲁棒金刚石磁测量方法,通过在|m_(s)=±1>态未完全退简并的情况下,同时利用|m_(s)=0>次能级和|m_(s)=±1>次能级间的跃迁测量磁场,可以使由温度漂移导致D变化所产生的影响被抵消掉。目前,该方法已经可以使磁测量结果的漂移降低为原来的1/7,通过后续的改进,这种温度鲁棒的金刚石磁测量方法有望在未来被应用于生物磁学和空间科学研究中。

实验研究DQC1算法中的量子失谐

量子失谐被认为是确定性单比特量子计算(DQC1)中指数加速的来源。在实际噪声环境下实现DQC1算法并研究其中量子失谐的作用具有重要意义。我们在电子自旋共振(ESR)体系上演示了DQC1算法,并且观察到了非零的量子失谐。此外,我们发现量子失谐的大小与初态的纯度α及量子Fisher信息的大小具有对应关系。实验结果为揭示量子失谐在DQC1中的作用提供了有力证据,并有助于进一步理解量子算法中指数加速的来源。

Distribution and origin of brine-type Li-Rb mineralization in the Qaidam Basin,NW China

The Qaidam Basin on the Qinghai-Tibet Plateau is well endowed with a variety of critical metals,such as Li and Rb.However,little is known about the distribution,source,and enrichment mechanisms of these elements.In this paper,we present results of systematic geochemical and H-O-B isotopic analyses of brines in the Tertiary and Quaternary sediments of the Qaidam basin.The results reveal that the paleobrines from oil-bearing anticlines at Dafengshan,Nanyishan,Youquanzi,Jiandingshan,and Jianshishan are significantly enriched in Li and Rb,whose contents are 81.1-128.9 mg L^(-1)and 4.5-29.2 mg L^(-1),respectively,reaching levels of economic significance.High Rb contents(up to 12.5 mg L^(-1))and well-endowment of Li also characterize the Dongtai,Xitai,Yiliping,and Senie salt lakes in the Qaidam Basin.The Tertiary paleobrine average inδD andδ18O at-40.7‰and 2.84‰,respectively.The paleobrine with the highest Li and Rb hasδD andδ^(18)O values close to magmatic water.Theδ^(11)B values are lower than those of river water but close to those of geothermal fluids,suggesting that replenishment by deep magmatic hydrothermal fluid is most likely the key mechanism for the anomalous enrichment of these elements in the paleobrines,though evaporation and water-rock reactions have contributed to the critical metal mineralization.The anomalous enrichment of Li and Rb in modern salt lake brines is closely related to the input of volcanic geothermal water.The relatively high Li and Rb contents of intercrystalline brines in salt lakes of the western Qaidam Basin and the increase of Li and Rb contents with increasing depth were caused by upwelling of local paleobrines along the fault zones.

Highly sensitive tuning of lattice thermal conductivity of graphenelike borophene by fluorination and chlorination

Boron-based 2D materials are of current interest.However,graphene-like geometry is unstable for B due to the electron deficiency,which can be stabilized by introducing H,F and Cl.Here,using density functional theory combined with phonon Boltzmann transport equation,we perform systematic studies on how the functionalization changes the lattice thermal conductivity(LTC).We find that when going from hydrogenation to fluorination and chlorination,the LTC along zigzag direction changes from 367.6 to 211.3 and 43.0 W/(rrvK),while the corresponding values in armchair direction are 279.6,198.9,and 41.6 W/(m·K),respectively.These huge differences imply the sensitivity of LTC to functionalization,which can be attributed to the enhanced anharmonicity as revealed by analyzing group velocity,Gruneisen parameter,anharmonic scattering rates,and three-phonon scattering space.

Reservoir characteristics and controlling factor of shale gas in Lower Cambrian Niutitang Formation, South China

Large-scale exploration and development of shale gas in Lower Cambrian Niutitang Formation of South China has been carried out in recent years,but the result is not good,only except some drilling wells in Jingyan-Qianwei area of Sichuan Basin and Yichang of Hubei obtain some commercial gas flows.In order to clarify reasons for failure of shale gas exploration and development in Niutitang Formation around Sichuan Basin and to provide reservoir geological parameters for subsequent efficient exploration and development,taking a case of shale gas reservoirs in Lower Cambrian Niutitang Formation in northeast Chongqing around Sichuan Basin,some experimental methods,such as analysis of organic carbon pyrolysis,determination of equivalent vitrinite reflectance,focused ion beam scanning electron microscope(FIB-SEM)and other are adopted in this study.The results show that the average TOC of shale samples in Niutitang Formation in northeast Chongqing is 3.1%,the equivalent vitrinite reflectance ranges from 3.0%to 4.0%,and the degree of thermal evolution reaches the post-matureemetamorphic stage.Due to excessively high degree of the thermal evolution,organic pores in shale samples are not developed in Lower Cambrian Niutitang Formation in the study area,instead,micro-nano pores dominated by intergranular pores and intragranular pores are developed in the shale.The degree of the thermal evolution controls the sustaining gas generation of kerogen and retained liquid hydrocarbons in the shale,it also controls the development of organic pores of the shale.The evolution of organic pores and hydrocarbon generation in the shale of Niutitang Formation in northeast Chongqing around Sichuan Basin do not match best with each other,that is,during development period of a large number of organic pores,thermal evolution degree of reservoirs is further enhanced because the strata are not uplifted in time,therefore,the quantity of organic pores is decreased sharply,the shale gas would be escaped due to the absence of organic pores as effective storage space after the shale gas generation.Therefore,the efficient exploration and development of the shale gas in Lower Cambrian Niutitang Formation in South China should be focused on the shale development area where the shale is characterized by moderate thermal evolution degree(2.0%<R_(o)<3.0%)and shallow buried depth,that is,the shale distribution area with paleo-uplift or paleo-buried hill.