Maximum frequent pattern generation from a large database of transactions and items for association rule mining is an important research topic in data mining. Association rule mining aims to discover interesting corre...Maximum frequent pattern generation from a large database of transactions and items for association rule mining is an important research topic in data mining. Association rule mining aims to discover interesting correlations, frequent patterns, associations, or causal structures between items hidden in a large database. By exploiting quantum computing, we propose an efficient quantum search algorithm design to discover the maximum frequent patterns. We modified Grover’s search algorithm so that a subspace of arbitrary symmetric states is used instead of the whole search space. We presented a novel quantum oracle design that employs a quantum counter to count the maximum frequent items and a quantum comparator to check with a minimum support threshold. The proposed derived algorithm increases the rate of the correct solutions since the search is only in a subspace. Furthermore, our algorithm significantly scales and optimizes the required number of qubits in design, which directly reflected positively on the performance. Our proposed design can accommodate more transactions and items and still have a good performance with a small number of qubits.展开更多
The modification of polysulfide electrolyte with additives has been demonstrated as an effective way to improve the photovoltaic performance of quantum dot-sensitized solar cells(QDSCs). Most of these additives can in...The modification of polysulfide electrolyte with additives has been demonstrated as an effective way to improve the photovoltaic performance of quantum dot-sensitized solar cells(QDSCs). Most of these additives can inhibit the charge recombination processes at photoanode/electrolyte interface and favor the improvement of V oc of cell devices. Herein, we showed that the incorporation of elemental selenium(Se) in polysulfide electrolyte to form polyselenosulfide species can notably improve the performance of QDSCs. Unlike previous reports, we present here an integrated investigation of the effects of polyselenosulfide species in polysulfide electrolyte on the photovoltaic performance of QDSCs from both of the photoanode and counter electrode(CE) aspects. Electrochemical impedance spectroscopy(IS) and opencircuit voltage-decay(OCVD) measurements demonstrated that the introduction of Se into polysulfide electrolyte can not only retard charge recombination at photoanode/electrolyte interface, but also reduce the charge transfer resistance at CE/electrolyte interface, resulting in the improvement of J sc and FF values. Consequently, the average efficiency of Zn-Cu-In-Se QDSCs was improved from 9.26% to 9.78% under AM 1.5 G full one sun illumination.展开更多
On the basis of the relationship between the Hamiltonian of spin 1/2 quantum system under control and the energy level structure and transitions,a radio frequency pulse sequence is designed using intuitive and half co...On the basis of the relationship between the Hamiltonian of spin 1/2 quantum system under control and the energy level structure and transitions,a radio frequency pulse sequence is designed using intuitive and half counter-intuitive sequences of pulse to transfer the population of the 3-qubit system coherently.The effectiveness of the designed control sequence is verified through the system simulation experiment of the evolution of state. In principle,the design method of the control pulse sequence proposed can be generalized to use in the quantum systems of higher dimension.展开更多
量子点敏化太阳能电池(Quantum Dot-Sensitized Solar cells,QDSCs)制备工艺简单,制造成本低廉,是一种有希望的新型太阳能电池。QDSCs利用量子点具有光谱吸收强、尺寸可调和多激子效应等优点,能够提高其光电转换效率;同时,利用无机量子...量子点敏化太阳能电池(Quantum Dot-Sensitized Solar cells,QDSCs)制备工艺简单,制造成本低廉,是一种有希望的新型太阳能电池。QDSCs利用量子点具有光谱吸收强、尺寸可调和多激子效应等优点,能够提高其光电转换效率;同时,利用无机量子点替代染料作为敏化剂,能够解决染料敏化太阳能电池(DSCs)的稳定性问题。但是,QDSCs光电转换效率较低是制约其应用的主要问题。近年来,通过改变和调控对电极的材料和电子特性提高QDSCs的光电效率的方法受到了广泛关注。本文综述了QDSCs对电极材料的制备方法、微观形貌和晶体结构;重点分析了金属化合物、复合材料、杂化材料、多元金属硫族化合物、导电聚合物和碳材料对电极对量子点敏化太阳能电池的电荷转移阻抗、光电性能等参数的影响;并分析影响其电催化活性和电子传输性能的主要因素。最后,提出通过表面修饰、复合和杂化等方法构筑新型对电极材料,进而改善和提高QDSCs转换效率和稳定性,是今后的研究重点和研究方向。展开更多
采用水热法和磁控溅射法相结合,在FTO导电玻璃上分别制备金属Pt和Cu1.8S/CuS薄膜,构成复合对电极,并将其成功应用到CdS量子点敏化TiO_2纳米管太阳电池中.这种复合对电极能够与多硫电解质相匹配,有效地提高量子点敏化太阳能电池的光电转...采用水热法和磁控溅射法相结合,在FTO导电玻璃上分别制备金属Pt和Cu1.8S/CuS薄膜,构成复合对电极,并将其成功应用到CdS量子点敏化TiO_2纳米管太阳电池中.这种复合对电极能够与多硫电解质相匹配,有效地提高量子点敏化太阳能电池的光电转化效率.利用X线衍射仪(XRD)、场发射扫描电镜电极(SEM)和透射电镜(TEM)对复合对电极和TiO_2纳米管光阳极的结构与形貌进行表征,通过AM1.5模拟太阳光测试系统对其光电性能进行表征.结果表明:复合对电相较与传统的Pt对电极和Cu1.8S/CuS单一对电极而言具有明显优势,提高了CdS量子点敏化太阳能电池的短路电流密度(9.27 m A/cm^2)、开路电压(0.577 V)和填充因子(49.4%),最终获得2.64%的光电转化效率.展开更多
铜锌锡硫(CZTS)半导体常作为对电极材料被应用于量子点敏化太阳能电池(QDSCs)中,然而效率一直低于4%。本文采用热注入法合成出纳米尺寸的CZTS并制成对电极(CZTS/FTO),用其组装的Cd Se QDSCs和Cd Se Te QDSCs的效率(PCE)分别达到了5.75%...铜锌锡硫(CZTS)半导体常作为对电极材料被应用于量子点敏化太阳能电池(QDSCs)中,然而效率一直低于4%。本文采用热注入法合成出纳米尺寸的CZTS并制成对电极(CZTS/FTO),用其组装的Cd Se QDSCs和Cd Se Te QDSCs的效率(PCE)分别达到了5.75%和7.64%。电化学阻抗谱、塔菲尔极化等表征证明电池效率的提高与CZTS良好的导电性及催化活性联系密切。展开更多
文摘Maximum frequent pattern generation from a large database of transactions and items for association rule mining is an important research topic in data mining. Association rule mining aims to discover interesting correlations, frequent patterns, associations, or causal structures between items hidden in a large database. By exploiting quantum computing, we propose an efficient quantum search algorithm design to discover the maximum frequent patterns. We modified Grover’s search algorithm so that a subspace of arbitrary symmetric states is used instead of the whole search space. We presented a novel quantum oracle design that employs a quantum counter to count the maximum frequent items and a quantum comparator to check with a minimum support threshold. The proposed derived algorithm increases the rate of the correct solutions since the search is only in a subspace. Furthermore, our algorithm significantly scales and optimizes the required number of qubits in design, which directly reflected positively on the performance. Our proposed design can accommodate more transactions and items and still have a good performance with a small number of qubits.
基金supported by the National Natural Science Foundation of China (NFSC nos. 51732004 , 91433106 , 21703071 , 21805093)
文摘The modification of polysulfide electrolyte with additives has been demonstrated as an effective way to improve the photovoltaic performance of quantum dot-sensitized solar cells(QDSCs). Most of these additives can inhibit the charge recombination processes at photoanode/electrolyte interface and favor the improvement of V oc of cell devices. Herein, we showed that the incorporation of elemental selenium(Se) in polysulfide electrolyte to form polyselenosulfide species can notably improve the performance of QDSCs. Unlike previous reports, we present here an integrated investigation of the effects of polyselenosulfide species in polysulfide electrolyte on the photovoltaic performance of QDSCs from both of the photoanode and counter electrode(CE) aspects. Electrochemical impedance spectroscopy(IS) and opencircuit voltage-decay(OCVD) measurements demonstrated that the introduction of Se into polysulfide electrolyte can not only retard charge recombination at photoanode/electrolyte interface, but also reduce the charge transfer resistance at CE/electrolyte interface, resulting in the improvement of J sc and FF values. Consequently, the average efficiency of Zn-Cu-In-Se QDSCs was improved from 9.26% to 9.78% under AM 1.5 G full one sun illumination.
基金supported by the National Natural Science Foundation of China (60774098)the National Key Basic Research Program (2006922004)
文摘On the basis of the relationship between the Hamiltonian of spin 1/2 quantum system under control and the energy level structure and transitions,a radio frequency pulse sequence is designed using intuitive and half counter-intuitive sequences of pulse to transfer the population of the 3-qubit system coherently.The effectiveness of the designed control sequence is verified through the system simulation experiment of the evolution of state. In principle,the design method of the control pulse sequence proposed can be generalized to use in the quantum systems of higher dimension.
文摘量子点敏化太阳能电池(Quantum Dot-Sensitized Solar cells,QDSCs)制备工艺简单,制造成本低廉,是一种有希望的新型太阳能电池。QDSCs利用量子点具有光谱吸收强、尺寸可调和多激子效应等优点,能够提高其光电转换效率;同时,利用无机量子点替代染料作为敏化剂,能够解决染料敏化太阳能电池(DSCs)的稳定性问题。但是,QDSCs光电转换效率较低是制约其应用的主要问题。近年来,通过改变和调控对电极的材料和电子特性提高QDSCs的光电效率的方法受到了广泛关注。本文综述了QDSCs对电极材料的制备方法、微观形貌和晶体结构;重点分析了金属化合物、复合材料、杂化材料、多元金属硫族化合物、导电聚合物和碳材料对电极对量子点敏化太阳能电池的电荷转移阻抗、光电性能等参数的影响;并分析影响其电催化活性和电子传输性能的主要因素。最后,提出通过表面修饰、复合和杂化等方法构筑新型对电极材料,进而改善和提高QDSCs转换效率和稳定性,是今后的研究重点和研究方向。
文摘采用水热法和磁控溅射法相结合,在FTO导电玻璃上分别制备金属Pt和Cu1.8S/CuS薄膜,构成复合对电极,并将其成功应用到CdS量子点敏化TiO_2纳米管太阳电池中.这种复合对电极能够与多硫电解质相匹配,有效地提高量子点敏化太阳能电池的光电转化效率.利用X线衍射仪(XRD)、场发射扫描电镜电极(SEM)和透射电镜(TEM)对复合对电极和TiO_2纳米管光阳极的结构与形貌进行表征,通过AM1.5模拟太阳光测试系统对其光电性能进行表征.结果表明:复合对电相较与传统的Pt对电极和Cu1.8S/CuS单一对电极而言具有明显优势,提高了CdS量子点敏化太阳能电池的短路电流密度(9.27 m A/cm^2)、开路电压(0.577 V)和填充因子(49.4%),最终获得2.64%的光电转化效率.
文摘铜锌锡硫(CZTS)半导体常作为对电极材料被应用于量子点敏化太阳能电池(QDSCs)中,然而效率一直低于4%。本文采用热注入法合成出纳米尺寸的CZTS并制成对电极(CZTS/FTO),用其组装的Cd Se QDSCs和Cd Se Te QDSCs的效率(PCE)分别达到了5.75%和7.64%。电化学阻抗谱、塔菲尔极化等表征证明电池效率的提高与CZTS良好的导电性及催化活性联系密切。
