里德堡原子开放系统的量子相干效应及其应用

The alkali atoms with the outer electron being in the excited state of a highly principal quantum number are conventionally referred to as Rydberg atoms. Because of the intrinsic Förster interaction between any pairs of the highly-excited Rydberg atoms, a laser-driven Rydberg-atom system exhibits temporal and spatial correlations as well as strong optical nonlinearity, and therefore manifests itself as being the essential architecture for studying strongly-correlated many-body physics. In this project, we will study coherent quantum effects of a driven ultra-cold Rydberg-atom system, and consider the effect of the decoherence, arising from atomic spontaneous emission, atomic collision and thermal vibration, laser intensity and phase noise etc., on the dissipative dynamics of the system, based on which we will manage to construct an effective model for describing the multi-atom interaction and to reveal the experimentally observable quantum signatures; We will also find a way to enhance the photon-photon interaction by manipulating multiple Rydberg levels and by tuning the Förster resonance based on the Rydberg electromagnetically induced transparency, and use it to construct an effective interaction model to describe the strongly-correlated multi-photon system and to implement a deterministically optical binary quantum logic gate; finally, by interfacing cold Rydberg atoms with other quantum architectures, such as optical cavity and optical waveguide, the coherent quantum effects of the hybrid systems will be explored to design newly-typed quantum devices and to study exotic quantum optical phenomena. Our studies must have promising applications in quantum precision measurement and all-optical quantum information processing.

里德堡原子通常是指最外层电子处于主量子数较高的激发态能级的碱金属原子。由于高激发态里德堡原子之间的Förster內禀相互作用，受激光驱动的里德堡原子系统呈现出时间、空间关联和强光学非线性，因此成为研究强关联多体物理的重要物理载体。在本项目中，我们将研究受驱超冷里德堡原子系统的多体量子相干效应，通过考虑系统在原子自发辐射、原子碰撞和位置起伏、激光强度和相位噪声等消相干因素影响下的耗散动力学，建立蕴含有效耗散的多原子相互作用模型，揭示可于实验观测的系统量子特征；基于里德堡电磁诱导透明，研究通过调控多个里德堡能级和调谐Förster共振进一步增强光子-光子之间的相互作用，并用于构建确定性两光子量子逻辑门和强关联多光子有效模型；基于里德堡原子与光学腔、光波导等耦合的复合量子系统，探索利用该开放系统的相干量子效应设计新型量子器件和研究新奇量子光学现象。相关成果可望应用于量子精密测量和光量子信息处理。

近几年，利用囚禁于光镊或光晶格的里德堡原子阵列，人们集中开展了多比特量子逻辑门构建、量子非线性光学和非平衡临界行为等方面的研究，从理论和实验上证明了里德堡原子在量子模拟和量子精密测量等领域的广泛应用前景。在本项目中，我们基于该物理系统提出了一系列可用于量子信息处理的理论方案：利用里德堡原子的多分量里德堡相互作用,通过绝热调制激光相位构建几何量子逻辑门；利用Förster能级缺陷的周期性调制，通过Landau-Zener动力学控制实现条件相位门；基于里德堡反阻塞效应，通过李雅普诺夫控制耗散制备多原子纠缠态；我们提出一个新的里德堡分子缀饰方案，用于增强远距离相干强度，并通过自旋回声脉冲序列控制实现里德堡原子的快速自旋压缩；为基于里德堡原子的量子信息处理和量子传感实验研究提供理论参考。此外，在交叉领域，我们在超导电路量子网络中提出利用耗散控制实现多比特初态设置；在Dicke模型中研究了超越热力学极限条件的量子相变；在腔光力学系统中，提出了制备连续变量纠缠和压缩的多个有效方法；为下一阶段研究工作的开展奠定了良好的基础。