Towards controlled interaction of Rydberg excitons in integrated and scalable solid state devices

我们研究了半导体铜矿(Cu2O)中的里德堡激子，它的主量子数高达n=25，激子玻尔半径在微米范围内。这些半导体中的巨型单量子物体最近才被发现，它们作为量子设备的潜力尚未实现。这些系统的许多性质是未知的，仍需确定。我们使用人工生长和自然生长的几毫米量级的Cu2O单晶，在1.5K的温度下，使用570 nm波长范围内的可调谐窄带半导体激光器，围绕黄色p-、S-和d-激子系列进行AM/FM调制光谱。在半导体表面印有飞秒激光直接写入的微透镜，可以聚焦到微米级的焦点，通过倾斜入射角，可以进行空间分辨的泵浦-探测实验。这给出了关于库仑相互作用距离的直接信息，并确定了里德堡阻塞半径。电场和磁场都会引起对称性破坏，从而改变波函数的性质，光学跃迁选择规则，从而改变相互作用。利用我们的空间分辨泵浦-探测方案，我们可以研究EIT耦合方案对里德堡激子相互作用的影响。3D打印相位板和双子束碾磨菲涅耳相位板将允许在铜矿晶体上的衍射有限焦点中直接产生适当的角动量光。由于里德堡激子的大小为100 nm，它们与OAM光模式的空间重叠是研究额外角度光的偶极选择规则违反的理想方法。光纤方案与多芯单模光纤和打印透镜的近衍射限制成像相结合，将允许一个集成的纯光纤方案，该方案可以处理整个里德堡激子矩阵，并且可以通过透明电极网进行控制和斯塔克切换。这将导致一种可扩展的光纤集成设备，即使在亚开尔文温度下，也可以在没有光学窗口的低温恒温器中进行测量，尽可能避免声子散射。在SPP1929中，我们将受益于与多特蒙德的Manfred Bayer小组的相互作用，他也在研究里德堡激子，以及与其他原子物理小组，如斯图加特的Tilman Pfau和Robert Löw，他们处理原子系统中的Rydberg相互作用，以及用于非线性开关的EIT和腔QED方案。此外，我们在实验上与Gerhard Birkl在Darmstadt合作，他使用我们的微透镜阵列来实现他的原子里德堡原子阵列。我们将与Rostock的Stefan Scheel和斯图加特的HanspterBüchler/Jörg Main的理论小组合作，讨论OAM选择规则和偶极矩阵元以及里德伯格量子阱激子的能量计算。

We study Rydberg excitons in the semiconductor cuprite (Cu2O),which exhibit principal quantum numbers as high as n=25 andexcitonic Bohr radii in the micrometer range. These giant singlequantum objects in semiconductors have been discovered onlyrecently, and their potential as quantum devices has yet to berealized. Many properties of these systems are unknown and stillhave to be determined. We use artificially grown as well as naturalsingle Cu2O crystals of several mm² size and carry out AM/FMmodulation spectroscopy around the yellow p-, s-, and d-excitonseries at temperatures down to 1.5 K, using a tunable narrowbanddiode laser in the 570 nm wavelength range. Microlenses printed withfemtosecond direct laser writing on top of the semiconductors willallow for focusing down to micrometer sized focal spots, and by tiltingthe incidence angle, spatially resolved pump-probe experiments canbe carried out. This gives direct information on the Coulombinteraction distance and determines the Rydberg blockade radius.Both electric and magnetic fields cause a symmetry breaking andmodify the wavefunction nature, the optical transition selection rules,and hence the interaction. Using our spatially resolved pump-probescheme, we can investigate the influence of EIT-coupling schemesonto the Rydberg exciton interactions. 3D printed phaseplates andion-beam milled Fresnel-phaseplates will allow for generation oforbital angular momentum light directly in diffraction limited focalspots on the cuprite crystal. As the Rydberg excitons are several 100nm in size, their spatial overlap with the OAM light mode is ideal tostudy violation of dipolar selection rules upon additional angularmomentum of light. The fiber scheme in combination with multicoresingle mode fibers and near-diffraction limited imaging by printedlenses will allow for an integrated fiber-only scheme which canaddress a whole matrix of Rydberg excitons, being controllable andStark switchable through the transparent electrode grid. This will leadtowards a scalable, fiber-integrated device which can be measured incryostats with no optical windows even at sub-Kelvin temperatures,avoiding phonon scattering as much as possible. Within theSPP1929, we are going to benefit from interactions with the group ofManfred Bayer in Dortmund, who is also studying Rydberg excitons,as well as with the other atomic physics groups such as the one ofTilman Pfau and Robert Löw in Stuttgart, who deal with Rydberginteraction in atomic systems as well as EIT and cavity QED schemesfor nonlinear switching. Additionally, we experimentally collaboratewith Gerhard Birkl in Darmstadt, who uses our microlens arrays for hisatomic Rydberg atom arrays. We are going to collaborate with thetheory groups of Stefan Scheel in Rostock and HanspeterBüchler/Jörg Main in Stuttgart regarding the OAM selection rules and dipole matrix elements as well as the Rydberg quantum well excitonenergy calculations.