phononics; quantum dot; spin; photonics; van der Waals heterostructure; microcavity
Uppu Ravitej, Eriksen Hans T., Thyrrestrup Henri, Uğurlu Aslı D., Wang Ying, Scholz Sven, Wieck Andreas D., Ludwig Arne, Löbl Matthias C., Warburton Richard J., Lodahl Peter, Midolo Leonardo (2020), On-chip deterministic operation of quantum dots in dual-mode waveguides for a plug-and-play single-photon source, in Nature Communications
, 11(1), 3782-3782.
Löbl Matthias C., Spinnler Clemens, Javadi Alisa, Zhai Liang, Nguyen Giang N., Ritzmann Julian, Midolo Leonardo, Lodahl Peter, Wieck Andreas D., Ludwig Arne, Warburton Richard J. (2020), Radiative Auger process in the single-photon limit, in Nature Nanotechnology
, 15(7), 558-562.
Roch Jonas G., Miserev Dmitry, Froehlicher Guillaume, Leisgang Nadine, Sponfeldner Lukas, Watanabe Kenji, Taniguchi Takashi, Klinovaja Jelena, Loss Daniel, Warburton Richard J. (2020), First-Order Magnetic Phase Transition of Mobile Electrons in Monolayer MoS2, in Physical Review Letters
, 124(18), 187602-187602.
Löbl Matthias C., Scholz Sven, Söllner Immo, Ritzmann Julian, Denneulin Thibaud, Kovács András, Kardynał Beata E., Wieck Andreas D., Ludwig Arne, Warburton Richard J. (2019), Excitons in InGaAs quantum dots without electron wetting layer states, in Communications Physics
, 2(1), 93-93.
Najer Daniel, Söllner Immo, Sekatski Pavel, Dolique Vincent, Löbl Matthias C., Riedel Daniel, Schott Rüdiger, Starosielec Sebastian, Valentin Sascha R., Wieck Andreas D., Sangouard Nicolas, Ludwig Arne, Warburton Richard J. (2019), A gated quantum dot strongly coupled to an optical microcavity, in Nature
, 575(7784), 622-627.
Löbl Matthias C., Zhai Liang, Jahn Jan-Philipp, Ritzmann Julian, Huo Yongheng, Wieck Andreas D., Schmidt Oliver G., Ludwig Arne, Rastelli Armando, Warburton Richard J. (2019), Correlations between optical properties and Voronoi-cell area of quantum dots, in Physical Review B
, 100(15), 155402-155402.
Roch Jonas Gaël, Froehlicher Guillaume, Leisgang Nadine, Makk Peter, Watanabe Kenji, Taniguchi Takashi, Warburton Richard John (2019), Spin-polarized electrons in monolayer MoS2, in Nature Nanotechnology
, 14(5), 432-436.
Ding Dapeng, Appel Martin Hayhurst, Javadi Alisa, Zhou Xiaoyan, Löbl Matthias Christian, Söllner Immo, Schott Rüdiger, Papon Camille, Pregnolato Tommaso, Midolo Leonardo, Wieck Andreas Dirk, Ludwig Arne, Warburton Richard John, Schröder Tim, Lodahl Peter (2019), Coherent Optical Control of a Quantum-Dot Spin-Qubit in a Waveguide-Based Spin-Photon Interface, in Physical Review Applied
, 11(3), 031002-031002.
Leisgang Nadine, Roch Jonas G., Froehlicher Guillaume, Hamer Matthew, Terry Daniel, Gorbachev Roman, Warburton Richard J. (2018), Optical second harmonic generation in encapsulated single-layer InSe, in AIP Advances
, 8(10), 105120-105120.
Javadi Alisa, Ding Dapeng, Appel Martin Hayhurst, Mahmoodian Sahand, Löbl Matthias Christian, Söllner Immo, Schott Rüdiger, Papon Camille, Pregnolato Tommaso, Stobbe Søren, Midolo Leonardo, Schröder Tim, Wieck Andreas Dirk, Ludwig Arne, Warburton Richard John, Lodahl Peter (2018), Spin–photon interface and spin-controlled photon switching in a nanobeam waveguide, in Nature Nanotechnology
, 13(5), 398-403.
Thyrrestrup Henri, Kiršanskė Gabija, Le Jeannic Hanna, Pregnolato Tommaso, Zhai Liang, Raahauge Laust, Midolo Leonardo, Rotenberg Nir, Javadi Alisa, Schott Rüdiger, Wieck Andreas D., Ludwig Arne, Löbl Matthias C., Söllner Immo, Warburton Richard J., Lodahl Peter (2018), Quantum Optics with Near-Lifetime-Limited Quantum-Dot Transitions in a Nanophotonic Waveguide, in Nano Letters
, 18(3), 1801-1806.
Roch Jonas G., Leisgang Nadine, Froehlicher Guillaume, Makk Peter, Watanabe Kenji, Taniguchi Takashi, Schönenberger Christian, Warburton Richard J. (2018), Quantum-Confined Stark Effect in a MoS 2 Monolayer van der Waals Heterostructure, in Nano Letters
, 18(2), 1070-1074.
Quantum communication and quantum computation offer compelling advantages over their classical counterparts. Quantum communication over short distances is a reality; over long distances it is not. A fully-fledged quantum computer remains a very distant prospect but its potential to solve hard problems in chemistry and materials science make it an extremely important goal. Application of these quantum concepts with semiconductors offers a route to creating small, fast and scalable devices. However, while the materials have powerful advantages they are also complex with several inter-connected sub-systems (electronic charge, electronic spin, nuclear spins, phonons, photons). The physics of these materials, particularly with structure on the nano-scale, needs to be understood. The overriding goal of this project is to make leading contributions to the development of semiconductor-based quantum technology. There are three inter-linked strands, development of a quantum device, an investigation into some of the key physics, and an exploration of new materials.Tunable quantum dots in a tunable micro-cavityA self-assembled quantum dot has emerged as a leading contender for a source of single photons. The photons should be bright, pure and indistinguishable. Quantum dots far beneath the surface of the semiconductor emit pure and highly indistinguishable photons but the brightness is poor on account of the difficulties of extracting photons from the high-index semiconductor. High-brightness devices rely on nano-fabrication. In many cases, the nano-fabrication is both complex and invasive such that device yield is poor, and the photon purity and indistinguishable suffer. The proposal here is to solve this conundrum by embedding electrically-contacted quantum dots in a vertical micro-cavity: tunable quantum dots in a tunable micro-cavity. Nano-fabrication is bypassed: the quantum dots in the device are guaranteed to have ultra-high quality; contacting the device is trivial. The mirrors are built with known, ultra-high quality materials and techniques. Calculations show that two ideal limits can be reached, optimized photon collection and strong coupling. Remarkably, only a modest micro-cavity finesse (~1,000) is required for ultra-high photon extraction. These ideas will be implemented paying attention to all the crucial details which have hindered progress in the past. The technology will be simplified in order to create a device. An efficient spin-photon interface will be built by trapping a single spin (either electron or hole) in the quantum dot. Spin-photon entanglement protocols will be applied, and, on success, entanglement swapping operations to create high-rate spin-spin entanglements.Phononics with an embedded quantum dotThe electron-phonon interaction results in spin dephasing in a semiconductor. This is not inevitable. The phonon modes and their occupations can be controlled, a process of "phononics". Compared to "photonics", phononics has received almost no attention in the context of quantum dots. A phononic crystal will be created with a gap in the density of states in the few-GHz regime. When the electron spin Zeeman frequency lies in this gap, phonon-related spin relaxation should be suppressed. Conversely, the spin relaxation rate will be used to probe the local phonon density of states. A localized high-Q phonon mode will be created by using a phononic crystal to shield a small element from the bulk phonon modes. An embedded quantum dot will couple to the localized phonon mode. The aim is to reach the resolved sideband regime which allows the phonon number to be controlled, possibly to the phonon ground state, by optically driving the quantum dot.Quantum photonics with 2D semiconductorsThe only known way of "wiring up" self-assembled quantum dots is via photons. A "circuit" of self-assembled quantum dots does not exist largely because the quantum dots must be located deep below the surface. A tantalizing prospect is to create a quantum dot circuit with a two-dimensional semiconductor where, by its very nature, all the action takes place on or very close to the surface. Only the most rudimentary quantum dot-like elements exist in this materials class, for instance confined excitons in WSe2. The aim here is to create quantum dots in pre-defined locations with an electrical technique.