EACN Workshop 2022 Hardware For Semiconductor Based Quantum Repeater Technologies (Jonathan Finley) скачать в хорошем качестве

EACN Workshop 2022 Hardware For Semiconductor Based Quantum Repeater Technologies (Jonathan Finley)

Amongst the various hardware platforms explored within the QR.X project, semiconductor quantum dots (QDs) have favorable properties that make them suitable for building quantum links operating over optical fiber channels. They have near-unity quantum efficiencies, can emit near transform-limited single photons at rates approaching 1GHz, exhibit high photon indistinguishability (greater than 90% HOM) and can generate entangled photon pairs on demand. Their ability to natively emit in the telecoms O- and C-bands and the possibility to integrate them into advanced quantum photonic devices with photon extraction efficiencies greater than 60%, make them highly attractive as quantum sources for field testing of repeater links. This talk will give an overview of the activities of the semiconductor groups working in QR.X. We will begin by exploring advances in the growth of exceptionally low noise semiconductor QD nanomaterials and demonstrate the ability to tune emission frequencies from 950nm into the telecoms O- and C-bands. We will summarize the factors currently limiting the performance metrics discussed above and explore how coherent two-pulse quantum state preparation provides several advantages. Experiments and simulations demonstrate that this excitation scheme both suppresses re-excitation processes, that lead to multi-photon errors, while a precisely timed stimulation pulse reduces the timing jitter of emitted photons, leading to improved quantum state indistinguishability. Moreover, we will see how the polarization of the emitted photon can be programmed by the stimulation pulse. We will continue to explore activities related to spinqubits and spin-photon interfaces in single and coupled QDs and discuss how hole spin qubits promise better coherence properties than electron, by virtue of their weaker coupling to the fluctuating bath of nuclear spins in III-V semiconductors. We will explore how nano-photonic, opto-electronic, and straintunable device geometries can enhance the performance metrics of semiconductor-based sources. Finally, we will move from single dots to tunnel coupled pairs of QDs forming electrically tunable molecules. In this context, we will demonstrate electrically tunable coherent coupling of quantum states in the QDmolecule, high-rate quantum light generation and selective all optical spin-qubit preparation. Such QDmolecule devices are capable of hosting two interacting spin qubits with the potential to deterministically generate 2D photonic repeater graph states for measurement-based quantum communication protocols. MCQST ▶ Webseite: https://www.mcqst.de​​​​​​​ ▶ Twitter:   / mcqst_cluster​   ▶ LinkedIn:   / mcqst​