【作者】 王涵；

【导师】 钱静；

【作者基本信息】 华东师范大学 ， 原子与分子物理， 2023， 硕士

【摘要】 基于里德堡反阻塞效应,本工作研究了强探测极限下强相互作用里德堡系综原子的可控激发促进。里德堡原子是一类最外层电子被激发到主量子数很大能级的原子,拥有自发辐射寿命长、原子半径大、跃迁电偶极矩强等独特的物理性质,被广泛地应用于量子信息相关领域的研究中。里德堡原子之间存在强且可控的长程偶极-偶极相互作用,会使能级发生频移;因此控制原子的激发会影响一定范围内的所有原子的激发概率,这被称为里德堡阻塞效应。我们研究了基于阻塞效应形成的包含强关联的原子系综,考虑当辅助的控制原子与系综原子之间的相互作用恰好补偿里德堡能级失谐时,多个系综原子集体激发到里德堡态的概率大大增加。此时,系综原子自身的阻塞效应被抑制。这种反阻塞效应在本工作中被用于实现控制原子辅助的目标系综原子的集体激发促进。除此之外,在通过构建对称Dicke态对激发促进机制进行了详细地理论分析之后,我们用蒙特卡罗波函数方法数值模拟了真实实验条件下实现这种激发促进效应的约束条件。并由此拓展性地研究了在三维无亏损原子阵列中实现多比特受控非门构建的理论方案。我们通过进化算法确定了球型原子阵列表面多个控制比特的最佳空间位置,获得最大的非对称里德堡阻塞强度,从而能够使每个球面的控制原子对球心的目标原子进行独立操控。所构建的多比特量子门具有很大的保真度及鲁棒性,有望被用于发展大规模中性原子量子计算。更多还原

【Abstract】 Based on Rydberg antiblockade effect this paper presents a theoretical scheme of controllable excitation facilitation of Rydberg ensemble atoms in the strong-probe limit.Rydberg atoms,possessing one valence electron that is excited to a high-lying state with a big quantum principal number n,have versatile properties such as long spontaneous-emission lifetime,large atomic radius and strong electric dipole moment,which have been applied in the study of quantum information processing.The existence of long-range and controllable dipole-dipole interaction between two Rydberg atoms can make the energy level shifted;as a consequence the control atomic excitation would affect the excitation probability of all atoms within a certain range nearby.This arises the Rydberg blockade.We study an atom ensemble that contains strong correlations induced by blockade.When the control-ensemble atomic interaction is exactly overcome by the off-resonance detuning multi-ensemble atoms could be collectively excited to Rydberg state simultaneously with a growing probability.The blockade effect of atomic ensemble itself is suppressed.This so-called antiblockade effect is adopted to achieve controllable excitation facilitation of a targeted atomic ensemble here.In addition,after a detailed analysis for the facilitation mechanism by using symmetric Dicke state picture we numerically simulate the constraints of excitation facilitation under experimentally-accessible conditions with Monte Carlo wavefunction method.Also we extensively explore the realization of multiqubit controlled-NOT gates in a three-dimensional defect-free atomic array.Depending on the evolutional algorithm to determine the best positions of all control qubits on the spherical surface we obtain a maximal asymmetric blockade strength which enables an independent manipulation of the central target atom by using arbitrary control atom on the surface.The resulting multi qubit quantum gate has a high fidelity and a strong robustness to the environmental noises which can be used to develop large-scale quantum computing in the future.更多还原