Hybrid Cavity-QED with Rydberg Atoms and Microwave Circuits

处于高激发里德堡态的原子和分子可以表现出非常大的电偶极矩，约为1000德拜。这些大的偶极矩使它们非常适合于研究微波频率下的光-物质相互作用，以及自由空间和表面附近的长程偶极相互作用。它们还使得高里德堡态的样品非常容易利用不均匀的电场进行操纵和陷阱。最近发展的一种基于芯片的实验体系结构利用这些大的电偶极矩来控制接近表面的里德堡原子和分子的平移运动和内部量子态，这为(I)发展气相和固态系统相结合的混合量子信息处理方法，(Ii)研究里德堡原子/分子与表面之间的远程相互作用，以及(Iii)低温下气相分子样品的制备和研究开辟了新的机会。在这项提议中描述的工作中，计划开发和进一步发展这种结构，以一种包括前两个领域的方式，在可以描述为传统的腔-量子-电动力学(CALE-QED)和纯固态电路-QED之间的环境中进行实验。传统的腔-量子-电动力学(CALE-QED)涉及三维谐振器和气相中的二能级量子系统。为了实现这一点，将在长寿命的圆形里德堡态中制备氦原子。然后将这些态耦合到基于芯片的共面微波波导附近的微波场，以研究它们的相干时间和里德堡-原子-表面的长程相互作用。这些原子样品与基于芯片的超导微波谐振器的非共振相互作用将被用来实现新的基于芯片的器件，用于对里德堡样品的无损检测。从长远来看，这种混合系统中的气相里德堡原子将作为长相干时间量子存储器，通过基于芯片的微波谐振器耦合到可以执行快速操作的超导电路。通过这种方式，将绕过单独利用每个系统在量子信息处理中应用的挑战。

Atoms and molecules in highly-excited Rydberg states can exhibit very large electric dipole moments, on the order of 1000 Debye. These large dipole moments make them very well suited to studies of light-matter interactions at microwave frequencies, and long-range dipolar interactions in free-space and close to surfaces. They also make samples in high Rydberg states states very amenable to manipulation and trapping using inhomogeneous electric fields. The recent development of a new chip-based experimental architecture which exploits these large electric dipole moments to control the translational motion and internal quantum states of Rydberg atoms and molecules close to surfaces has opened up new opportunities in (i) the development of hybrid approaches to quantum information processing in which gas-phase and solid-state systems are combined, (ii) studies of long-range interactions between Rydberg atoms/molecules and surfaces, and (iii) the preparation and study of gas-phase molecular samples at low temperatures. In the work described in this proposal it is planned to exploit, and further develop, this architecture, in a manner which encompasses the first two of these areas, to perform experiments in a setting which can be described as a hybrid between traditional cavity-quantum-electrodynamics (cavity-QED), involving three-dimensional resonators and two-level quantum systems in the gas-phase, and purely solid-state circuit-QED.To achieve this helium atoms will be prepared in long-lived, circular Rydberg states. These states will then be coupled to microwave fields in the vicinity of chip-based co-planar microwave waveguides to study their coherence times and long-range Rydberg-atom--surface interactions. The off-resonant interaction of these atomic samples with chip-based superconducting microwave resonators will then be exploited for the realisation of new chip-based devices for non-destructive detection of the Rydberg samples.In the long term it is foreseen to use the gas-phase Rydberg atoms in this hybrid system as long-coherence-time quantum memories which are coupled via the chip-based microwave resonators to superconducting circuits in which fast operations can be performed. In this way, the challenges associated with exploiting each system individually for applications in quantum information processing will be circumvented.