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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - 2DQP (Two-dimensional quantum photonics)

Teaser

Summary

Quantum optics, the study of how discrete packets of light (photons) and matter interact, has led to the development of remarkable new technologies which exploit the bizarre properties of quantum mechanics. These quantum technologies are primed to revolutionize the fields of communication, information processing, and metrology in the coming years. Similar to contemporary technologies, the future quantum machinery will likely consist of a semiconductor platform to create and process the quantum information. However, to date the demanding requirements on a quantum photonic platform have yet to be satisfied with conventional bulk (three-dimensional) semiconductors.

To surmount these well-known obstacles, a new paradigm in quantum photonics is required. Initiated by the recent discovery of single photon emitters in atomically flat (two-dimensional) semiconducting materials, 2DQP aims to be at the nucleus of a new approach by realizing quantum optics with ultra-stable (coherent) quantum states integrated into devices with electronic and photonic functionality. We will characterize, identify, engineer, and coherently manipulate localized quantum states in this two-dimensional quantum photonic platform.

Work performed

Considerable progress has been achieved during the projectâ€™s first 18 months. Several milestones have been reached, in particular: 1) Demonstration of Purcell enhancement of a 2D quantum emitter. This enables faster single photon emission and helps overcome intrinsic dephasing mechanisms. 2) Deterministic incorporation of a 2D quantum emitter into a lithium niobite integrated photonic chip containing a directional coupler. This hybrid quantum circuit takes advantage of the ease of integeration of the 2D materials with optimal integrated photonic circuits. 3) Coulomb blockade in an atomically thin quantum dot coupled to a tunable Fermi reservoir. This enables electrical control of the quantum dot charge state, opening investigations into the spin dynamics. In addition, this opens new fundamental investigations of single spins coherently coupled to a Fermi sea. 4) Demonstration of out-of-plane orientation of luminescent excitons in atomically thin indium selenide flakes. This fundamental understanding opens a new opportunities in integrated circiuits which take advantage of a hard-to-find dipole orientation in most materials. 5) Investigation into the fundamental limits to coherent photon generation with solid-state atom-like transitions. This is applicable to all solid-state emitters and implies that non-deterministic quantum information protocols must be embraced. 6) New understanding of discrete interactions between a few interlayer excitons. This provides new fundamental understandings into the behaviour of interacting bosons. 7) Discovery of spin-layer locking of moire trapped interlayer valley excitons. This provides a new means to engineer few-level quantum systems in â€˜twistedâ€™ 2D materials, where two atomic layers are stacked with a relative rotation angle. In summary, significant progress has been achieved and the research program is largely proceeding to plan.

Final results

The project has produced several breakthroughs which have pushed the state-of-the-art. This includes fundamental investigations of the coherence of photons from solid-state quantum emitters, novel device architectures to realize control over single quantum particles, and the engineering of fundamentally new types of artificial atoms based on moire potentials in atomic layers stacked with a relative twist. The discovery of the artificial atoms in the twisted materials opens new avenues for investigation and exploitation which were not envisioned in the original proposal, and will be pursue vigorously. Nevertheless, the overall targets of the project are on course to be realized, including incorporation of 2D quantum emitters into functional electronic and photonic devices, and the generation and exploitation of coherent single photons from such devices.