[1] Univ Stuttgart, Inst Halbleiteropt & Funkt Grenzflachen, Ctr Integrated Quantum Sci & Technol IQST, Allmandring 3, D-70569 Stuttgart, Germany
[2] Univ Stuttgart, Res Ctr SCoPE, Allmandring 3, D-70569 Stuttgart, Germany
[3] Twenty One Semicond GmbH, Kiefernweg 4, D-72654 Neckartenzlingen, Germany
[4] Univ Ulm, Inst Funkt Nanosyst, Albert Einstein Allee 45, D-89081 Ulm, Germany