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By considering the identification problem of unknown but fixed Hamiltonian H = S0σ0 +∑i=x,y,z Siσi where σi (i = x, y, z) are pauli matrices and σ0=I, we explore the feasibility and limitation of empirically determining the Hamiltonian parameters for quantum systems under experimental conditions imposed by projective measurements and initialization procedures. It may be unsurprising to physicists that one can not obtain the knowledge of So no matter what kind of projective measurements and initialization are permitted, but the observation draws our attention to the importance of the parameter identifiability under different experimental condition. It has also been revealed that one can obtain the knowledge of |Sz| and Sx^2+Sy^2 at most when only the projective measurement {|0/(0|, |1/(1|} is permitted to perform on and initialize the qubit. Further more, we demonstrated that it is feasible to distinguish |Sx|, |Sy|, and |Sz| even without any a priori information about Hamiltonian if at least two kinds of projective measurement or initialization procedures are permitted. It should be emphasized that both projective measurements and initialization procedures play an important role in quantum system identification. 相似文献
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采用高温固相法在1 100℃下合成出一系列不同掺杂浓度的BaLa_(1-x)LiTeO_6∶xEu~(3+)(x=0.1~1)红色荧光粉,并对其结构、形貌、光谱特性及LED光色电性能进行了系统研究。结果表明,在BaLaLiTeO_6中Eu~(3+)的最大和最佳掺杂浓度均为x=0.4,更大的掺杂量将导致杂相和浓度猝灭的产生。在465 nm光激发下,该浓度的样品发射光谱中~5D_0→~7F_2与~5D_0→~7F_2强度比值达到了7.31,色品坐标值为(0.665,0.334),色纯度为99.7%,荧光寿命为660.9μs,绝对量子效率达到71.4%。在100℃时积分发光强度是室温时的84.5%,热激活能经计算为0.434 eV。基于该样品的红光LED灯珠能够发出明亮的红光。综上所述,该类荧光粉表现出良好的发光效率、色纯度及发光热稳定性,在白光LED中具有潜在的应用价值。 相似文献
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通过碘化镉与6-氨基-2-吡啶甲酸的水热反应,合成获得了一个单核结构的配位化合物[HCdI(apa)2](Hapa=6-氨基-2-吡啶甲酸).对标题配合物进行了X-射线单晶衍射测试,获得其晶体结构.标题配合物是一例单核结构的配位化合物,其晶体结构中的单核基本单元通过吡啶环间的π-π堆积连接组成一维Z字链.Z字链间通过氢键相互键连,构成了标题配位化合物[HCdI(apa)2]的三维超分子结构.标题配合物的光致发光性能测试表明,配位化合物[HCdI(apa)2]在室温下发射出蓝色荧光,其色坐标的值为(0.17,0.07).标题配合物的电子结构理论计算结果显示[HCdI(apa)2]的光致发光机理归属为配体内部的π-π﹡电子跃迁. 相似文献
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利用高温固相法制备了一种新型红色荧光粉(Gd_(1-x)Eu_x)_6(Te_(1-y)Mo_y)O_(12),研究了Eu~(3+)单掺和Eu~(3+),Mo~(6+)共掺Gd_6TeO_(12)荧光粉的结构、形貌和荧光性能.实验结果表明,所合成的粉体为纯相.在393 nm近紫外光激发下,(Gd_(1-x)Eu_x)_6(Te_(1-y)Mo_y)O_(12)荧光粉发出特征红光,位于632 nm处的发射主峰属于Eu~(3+)的~5D_0→~7F_2跃迁.当Eu~(3+)掺杂浓度超过20%(物质的量分数)时发光出现浓度淬灭,经证实这是由电偶极-电偶极相互作用造成的.随着工作温度升高,荧光粉发光强度减小,计算得到Eu~(3+)热淬灭过程中的激活能为0.1796 eV.当(Gd_(0.8)Eu_(0.2))_6TeO_(12)中共掺Mo~(6+_(取代Te~(6+)),该荧光粉发射光谱的峰位、强度变化不大,但是Mo~(6+)-O~(2-)电荷迁移态显著增大了近紫外波段的激发带宽度,可以有效提高激发效率.具有近紫外宽带激发特征的(Gd_(0.8)Eu_(0.2))_6(Te_(0.6)Mo_(0.4))O_(12)是一种潜在的白光LED用荧光粉材料. 相似文献
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Covellite CuS hexagonal nanoplatelets were prepared by a simple hydrothermal process at mild temperature, using sodium dodecyl benzene sulfonate (SDBS) as an assisting reagent. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and UV-vis absorption spectroscopy. An energy-dispersive X-ray spectrometer (EDS) was used to analyze the elementary compositions of the intermediate products. A possible formation mechanism of hexagonal nanoplatelets is discussed, using TEM observations. 相似文献
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利用高温固相法制备了BaGd_2(MoO_4)_4∶Tb~(3+)与BaGd_2(MoO_4)_4∶Tb~(3+),Eu~(3+)荧光粉,并借助于X射线衍射(XRD)、激发光谱、发射光谱及荧光衰减曲线对样品的结构及发光性能进行了表征。在290 nm激发下,BaGd_2(MoO_4)_4∶Tb~(3+)样品在550 nm处具有较强的绿光发射,表明该样品可用作绿色荧光粉。Tb~(3+)离子的最佳掺杂浓度为50%,电偶极间相互作用是引起浓度猝灭效应的主要原因。当在BaGd_2(MoO_4)_4∶Tb~(3+)荧光粉中共掺入Eu~(3+)离子后,可同时观测到Tb~(3+)与Eu~(3+)离子的特征发射峰。随Eu~(3+)掺杂浓度的升高,Tb~(3+)离子的发光强度逐渐下降,而Eu~(3+)离子的发光强度逐渐增加。根据BaGd_2(MoO_4)_4∶Tb~(3+),Eu~(3+)中Tb~(3+)离子的荧光寿命计算了Tb~(3+)与Eu~(3+)离子间的能量传递效率,并根据荧光寿命与激活离子掺杂浓度的关系证实了能量传递机制为电偶极间相互作用。 相似文献
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采用高温固相法成功合成出双钙钛矿结构SrGd_(1-x)LiTeO_6:xEu~(3+)(x=0.1-1.0)红色荧光粉,并采用X-射线衍射、漫反射光谱、光致发光光谱、电致发光光谱等测试手段对粉体的结构、光致发光特性以及发光二极管器件的光色电特性进行了系统研究.激发光谱、发射光谱和荧光衰减曲线测试结果表明Eu~(3+)的最佳掺杂浓度为x=0.6,更大的掺杂量会引起浓度猝灭.基于van Uitert浓度猝灭公式,提出一种更准确的表达形式用于拟合、分析能量传递类型,揭示出电偶极-电偶极作用导致浓度猝灭.Judd-Ofelt理论计算得出较高的跃迁强度参数和量子效率,说明高度畸变的非心C_1晶体场促使高效的超灵敏跃迁红光发射.在423 K时积分发光强度达到室温时的85.2%,热激活能经计算为0.2941 eV.基于此样品的发光二极管能够发出明亮的红光.综上所述,该类荧光粉表现出良好的发光效率、色纯度以及发光热稳定性,是一种潜在的近紫外激发白光发光二极管用红色荧光粉. 相似文献