Heterogenous quantum systems for single photon delay and pulse shaping (HQSys)

光子量子技术是一个令人兴奋的科学技术领域。潜在的应用包括安全量子通信、量子计算以及长期的量子互联网。它们的共同点是，信息被编码在单个光子中，充当飞行的量子比特。重要的是，这些飞行量子比特需要有效地与静止量子比特接口，以实现量子存储器和量子门。该项目的总体目标是开发和测试用于存储和检索以及单量子点光子的有效光谱/时间波形操纵的量子存储器。本项目首次实现了半导体量子点与碱性原子量子存储器之间的异质量子界面。这是量子纳米光子学的关键组成部分，可以在量子中继器协议中产生几乎完全无法区分的光子和接近统一的纠缠交换保真度。同时，我们设想量子信息可以被编码到单光子的时间包络和相位中，从而实现大字母表的高容量量子信息传输。基本的技术方法是将半导体量子点中高效和按需光子产生与在热原子蒸汽中实现的量子存储器相结合。通过原位电子束光刻技术，确定了单量子点CBR器件的源。在此，先进的原位EBL纳米技术平台保证了发射波长控制良好、光子提取效率高的QD量子光源的制作。在热碳蒸汽中，存储器遵循快速阶梯EIT方案。

Photonic quantum technology is an exciting field in science and technology. Potential applications include secure quantum communication, quantum computing and on the long-term the Quantum Internet. These have in common that information is encoded in single photons acting as flying qubits. Importantly, these flying qubits need to be efficiently interfaced with stationary qubits to implement quantum memories and quantum gates. The overarching goal of this project is to develop and test a quantum memory for the storage and retrieval as well as for the efficient spectral/temporal waveform manipulation of single quantum dot photons. Our project realizes for the first time a heterogeneous quantum interface between semiconductor quantum dots and a quantum memory realized in alkaline atoms. This key building block in quantum nanophotonics enables the generation of almost perfectly indistinguishable photons and near unity entanglement swapping fidelity in quantum repeater protocols. At the same time, we envision that quantum information can be encoded into the temporal envelope and phase of the single photons allowing for high capacity quantum information transfer with large alphabet.The underlying technological approach is to combine the efficient and on-demand photon generation in semiconductor quantum dots with quantum memories implemented in warm atomic vapor. The source is realized deterministically by in-situ electron beam lithography of single-QD CBR devices. Here, the advanced in-situ EBL nanotechnology platform guarantees the fabrication of QD quantum light source with well-controlled emission wavelength and high photon extraction efficiency. The memory follows a fast ladder EIT scheme in warm Cs vapor.