Clock frequency estimation under spontaneous emission

We investigate the quantum dynamics of a driven two-level system under spontaneous emission and its application in clock frequency estimation. By using the Lindblad equation to describe the system, we analytically obtain its exact solutions, which show three different regimes: Rabi oscillation, damped oscillation, and overdamped decay. From the analytical solutions, we explore how the spontaneous emission affects the clock frequency estimation. We find that under a moderate spontaneous emission rate, the transition frequency can still be inferred from the Rabi oscillation. Our results enable potential practical applications in frequency measurement and quantum control under decoherence.     

Cluster mean-field study of spinor Bose-Hubbard ladder:Ground-state phase diagram and many-body population dynamics

We present a cluster mean-field study for ground-state phase diagram and many-body dynamics of spin-1 bosons confined in a two-chain Bose-Hubbard ladder(BHL).For unbiased BHL,we find superfluid(SF)phase and integer filling Mott insulator(Int MI)phase.For biased BHL,in addition to the SF and Int MI phases,there appears half-integer filling Mott insulator(HInt MI)phase.The phase transition between the SF and Int MI phases can be first order at a part of phase boundaries,while the phase transition between the SF and HInt MI phases is always second order.By tuning the bias energy,we report on the change of the nature of SF-MI phase transitions.Furthermore,we study the effect of the spin-dependent interaction on the many-body population dynamics.The spin-dependent interaction can lead to rich dynamical behaviors,but does not influence the particle transfer efficiency.Our results indicate a way to tune the nature of the SF-MI phase transition and open a new avenue to study the many-body dynamics of spinor bosons in optical lattices.     

超冷原子系综的非高斯纠缠态与精密测量

量子精密测量是基于量子力学的基本原理对特定物理量实施测量,并利用量子效应提高测量精度的交叉科学.随着超冷原子实验技术的发展,超冷原子为量子精密测量提供了一个优异的研究平台.利用发展成熟的量子调控技术,人们可以基于超冷原子系综制备一些新奇的非高斯多粒子纠缠态.基于多体量子干涉,利用这些非高斯纠缠态作为输入,可以实现超越标准量子极限的高精度测量.本文简要综述这一研究领域的进展.     

稳态法测量冰导热系数的实验研究

测量固体导热系数的方法有很多，但能直接应用于冰的测量方法并不多.考虑到冰的零下低温环境等问题，本实验基于稳态法，根据傅里叶导热定律对相关细节进行了设计与改进，先后研究了待测冰直径与厚度的比值、环境温度和含盐率对冰的导热系数的影响.结果表明待测冰的直径厚度比值为12时，导热系数有最佳值2.25 W/m·K,且最佳测量环境温度为-10℃;不同浓度盐水冰的导热系数相比于纯水冰显著下降，且随着含盐率的升高降幅逐渐减小.     

Pt-MOx/CeO2水相重整催化剂上氧化物助剂对于水气变换反应的促进作用研究(英文)

甲醇水相重整是一种在相对温和条件下.的有效产氢路径。采用分步浸渍法制备Pt/CeO₂和Pt-MO_x/CeO₂(M=Fe、Cr、Mg、Mn)系列催化剂,并对其反应性能进行了研究。采用XPS、XRD、TEM、CO-TPD、NH₃-TPD、CO₂-TPD等表征手段对催化剂的金属价态、氧空位数量、金属粒子分布、CO吸附性能和催化剂的酸/碱性等性质进行表征和分析。通过关联结果表明,MO_x的加入削弱了Pt-CeO₂间的相互作用,促进了价态较低的Pt^δ+的生成,这有助于C-H键的裂解,促进甲醇的转化。Pt-MgO/CeO₂上的产氢量最高(164.78 mmol),CO和CH₄选择性相对较低,而Pt-CrO_x/CeO₂上的CH₄选择性最高(2.21%)_d对于Pt/CeO₃和Pt...