In contrast with conventional light-emitting diodes (LEDs) that emit billions of photons simultaneously to form a steady stream of light, a single photon emitter (SPE) generates exactly one photon on demand, with each photon indistinguishable from another. These characteristics are essential for photon-based quantum technologies under development. In addition, such capabilities should be realized in a material platform that enables precise, repeatable placement of SPEs in a fully scalable fashion compatible with existing semiconductor chip manufacturing.

(a) Illustration showing an AFM tip indenting the TMD/polymer structure to introduce local strain. (b) Patterned single photon emission in WSe2 induced by AFM indentation of the letters NRL and AFRL. (c) AFM indents produce single photon emitter “ornaments” on a monolayer WSe2 “Christmas tree.”

Researchers developed a way to directly write quantum light sources — which emit a single photon of light at a time — into monolayer semiconductors such as tungsten diselenide (WSe2). An atomic force microscope (AFM) was used to create nanoscale depressions or indents in a single monolayer of WSe2 on a polymer film substrate. A highly localized strain field is produced around the nano-indent, creating the single photon emitter state in the WSe2. Time-correlated measurements of this light emission confirmed the true single photon nature of these states. These emitters are bright, producing high rates of single photons, and spectrally stable — key requirements for emerging applications.

This quantum calligraphy allows deterministic placement and real-time design of arbitrary patterns of SPEs for facile coupling with photonic waveguides, cavities, and plasmonic structures. A nano-imprinting approach is effective in creating large arrays or patterns of quantum emitters for wafer-scale manufacturing of quantum photonic systems.

In addition to enabling versatile placement of SPEs, these results present a general methodology for imparting strain into two-dimensional (2D) materials with nanometer-scale precision, providing an invaluable tool for further investigations and future applications of strain engineering of 2D devices.

Quantum computation on a chip provides onboard capability to rapidly analyze very large data sets acquired by sensor arrays, so that the entire data set does not have to be transmitted, reducing bandwidth requirements.

For more information, contact the Naval Research Laboratory Public Affairs Office at This email address is being protected from spambots. You need JavaScript enabled to view it.; 202-767-2541.

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This article first appeared in the June, 2019 issue of Tech Briefs Magazine.

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