A team of researchers led by Alexander Holleitner, Jonathan Finley, physicists at Technical University of Munich (TUM) has succeeded in placing light sources in atomically thin material layers having an accuracy of few nanometres. It allows a series of applications in quantum technology ranging from quantum sensors, transistors to encryption technology for transmission of data. The study has been published in Nature Communications.
Earlier circuits on chips relied on electrons as carriers of information. However, in the coming days, photons carrying information at the speed of light will perform this task in optical circuits. The basic building blocks for such chips are quantum light sources connected with detectors and quantum fibre optic cables.
Julian Klein, the study’s lead author said that it is a first step in making optical quantum computers. The light sources need to coupled with photon circuits for future applications to make quantum calculations based on light possible. However, the critical point is the exact controlled placement of the light sources. Quantum light sources in materials such as diamond or silicon can be created but not precisely placed in the materials.
Physicists used a semiconductor layer, molybdenum disulfide as the initial material with a thickness of three atoms. Then they irradiated it with a beam of helium ions focused on a surface area of less than one nanometre. For generating optically active defects, molybdenum or sulfur atoms are hammered out of layer very precisely. The imperfections are traps for electron-hole pairs which emit the desired photons. The helium ion microscope at Center for Nanotechnology and Nanomaterials, Walter Schottky Institute was used for irradiating the material with accurate lateral resolution.
Researchers from TUM, University of Bremen, Max Planck Society developed the model for describing the energy state observed at theoretical imperfections.
In future scientists want to create complex light source patterns, in two-dimensional lateral lattice structures for researching multi-exciton phenomena. This is the experimental realisation of the theory within the context of the Bose-Hubbard model, accounting for complex processes in solids.
As the light sources have a similar underlying defect in the material they cannot be distinguished theoretically. This opens for new opportunities which are based on the quantum-mechanical principle of entanglement. Klein said that it is very much possible for the integration of quantum light sources in the photon circuits in a very elegant manner. Because of the high sensitivity, it is possible to make quantum sensors for smartphones and also make highly secure encryption technologies to transmit data.
Journal Reference: Nature Communications