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Experimentelle Nanophysik (Treutlein)

Projects & Collaborations

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Scalable High Bandwidth Quantum Network (sQnet)

Research Project  | 2 Project Members

Realizing a scalable quantum network is one of the grand challenges of quantum technology, with numerous potential applications in secure communication, quantum sensor networks, and distributed quantum computation. Single-photon sources and compatible quantum memories are key ingredients of quantum networks and the requirements on their performance are very stringent. In this project we will establish a scalable quantum networking platform that combines several high-performance elements: semiconductor quantum dot single-photon sources and compatible atomic vapor cell quantum memories implemented in scalable MEMS technology, operating with GHz bandwidth at convenient near-infrared wavelengths. Connectivity over long distance and to other platforms is enabled by efficient conversion of single photons to telecom wavelength using on-chip nonlinear optics. Combining these building blocks, we will demonstrate quantum networking tasks such as remote entanglement generation between quantum memories over a telecom fiber link. By demonstrating the basic functionality of a scalable quantum networking platform that operates at high efficiency and bandwidth, the project will lay the ground for the implementation of more advanced quantum networking protocols and scaling to multiple nodes.

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LASERLOOP / Laser loop for engineering long-distance interactions in hybrid quantum systems

Research Project  | 2 Project Members

Light is a powerful carrier of quantum information and an established tool to manipulate matter at the quantum level. In this action, we explore a novel technique of using light in quantum physics and technology: As a means to generate for the first time strong, quantum coherent interactions between different systems over macroscopic distances. Our approach relies on a laser loop that connects the systems and mediates coherent bidirectional interactions between them. This is possible due to a destructive interference of the quantum noise introduced by the light, otherwise responsible for decoherence. At the same time, information is erased from the output field, making the loop effectively closed to the environment. This makes it possible to achieve quantum coherent coupling between the systems.

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QUSTEC PhD fellowship - Hybrid quantum networks with atomic memories and quantum dot single-photon sources

Research Project  | 1 Project Members

This project aims at combining the high purity and large bandwidth of quantum dot single photons with the high efficiency and long storage times of atomic quantum memories into a hybrid quantum network architecture with advantageous properties. We already demonstrated that GaAs/AlGaAs quantum dots can emit transform-limited single photons tuned into resonance with rubidium atoms and that the temporal waveform of these photons can be controlled. In parallel, we realized a rubidium atomic quantum memory with a bandwidth of 660 MHz operating on the single-photon level. The goal of this project is to develop the two systems further and to interface them through an optical fiber link. Several improvements will be implemented to achieve low-noise operation: controlling the charge state of the dot and enhancing the photon collection efficiency with an optical cavity, as well as controlling the spin state of the atoms to suppress four-wave mixing noise by selection rules. After demonstrating storage and retrieval of quantum dot single photons in the atomic memory, we intend to perform basic quantum networking tasks with this hybrid system.