Mauro Brotons-Gisbert, Hyeonjun Baek, Alejandro Molina-Sánchez, Aidan Campbell, Eleanor Scerri, Daniel White, Kenji Watanabe, Takashi Taniguchi, Cristian Bonato and Brian D. Gerardot  Spin - layer locking of interlayer excitons trapped in moiré potentials,  https: / / www.nature.com/articles/s41563-020-0687-7 


Abstract

Van der Waals heterostructures offer attractive opportunities to design quantum materials. For instance, transition metal dichalcogenides (TMDs) possess three quantum degrees of freedom: spin, valley index and layer index. Furthermore, twisted TMD heterobilayers can form moiré patterns that modulate the electronic band structure according to the atomic registry, leading to spatial confinement of interlayer excitons (IXs). Here we report the observation of spin - layer locking of IXs trapped in moiré potentials formed in a heterostructure of bilayer 2H-MoSe2 and monolayer WSe2. The phenomenon of locked electron spin and layer index leads to two quantum-confined IX species with distinct spin - layer - valley configurations. Furthermore,we observe that the atomic registries of the moiré trapping sites in the three layers are intrinsically locked together due to the 2H-type stacking characteristic of bilayer TMDs. These results identify the layer index as a useful degree of freedom to engineer tunable few-level quantum systems in two-dimensional heterostructures. 

 

 

 

Zhe-Xian KoongGuillem Ballesteros-GarciaRaphaël ProuxDan DalacuPhilip J. PooleBrian D. Gerardot , Multiplexed Single Photons from Deterministically Positioned Nanowire Quantum Dots,  https://arxiv.org/abs/2005.05361


Abstract

Solid-state quantum emitters are excellent sources of on-demand indistinguishable or entangled photons and can host long-lived spin memories, crucial resources for photonic quantum information applications. However, their scalability remains an outstanding challenge. Here we present a scalable technique to multiplex streams of photons from multiple independent quantum dots, on-chip, into a fiber network for use off-chip. Multiplexing is achieved by incorporating a multi-core fiber into a confocal microscope and spatially matching the multiple foci, seven in this case, to quantum dots in an array of deterministically positioned nanowires. First, we report the coherent control of the emission of biexciton-exciton cascade from a single nanowire quantum dot under resonant two-photon excitation. Then, as a proof-of-principle demonstration, we perform parallel spectroscopy on the nanowire array to identify two nearly identical quantum dots at different positions which are subsequently tuned into resonance with an external magnetic field. Multiplexing of background-free single photons from these two quantum dots is then achieved. Our approach, applicable to all types of quantum emitters, can readily be scaled up to multiplex > 100  quantum light sources, providing a breakthrough in hardware for photonic based quantum technologies. Immediate applications include quantum communication, quantum simulation, and quantum computation.

H. Baek, M. Brotons-Gisbert, ZX Koong, A. Campbell, M. Rambach, K. Watanabe, T. Takashi, and BD Gerardot,  Highly tunable quantum light from moiré trapped excitons,  https://arxiv.org/ abs / 2001.04305 .