Quantum Light Sources Pave the Way for Optical Circuits
August 1, 2019 | Technical University of MunichEstimated reading time: 2 minutes

An international team headed up by Alexander Holleitner and Jonathan Finley, physicists at the Technical University of Munich (TUM), has succeeded in placing light sources in atomically thin material layers with an accuracy of just a few nanometers. The new method allows for a multitude of applications in quantum technologies, from quantum sensors and transistors in smartphones through to new encryption technologies for data transmission.
Previous circuits on chips rely on electrons as the information carriers. In the future, photons which transmit information at the speed of light will be able to take on this task in optical circuits. Quantum light sources, which are then connected with quantum fiber optic cables and detectors are needed as basic building blocks for such new chips.
An international team headed up by TUM physicists Alexander Holleitner and Jonathan Finley has now succeeded in creating such quantum light sources in atomically thin material layers and placing them with nanometer accuracy.
First Step Towards Optical Quantum Computers
“This constitutes a first key step towards optical quantum computers,” says Julian Klein, lead author of the study. “Because for future applications the light sources must be coupled with photon circuits, waveguides for example, in order to make light-based quantum calculations possible.”
The critical point here is the exact and precisely controllable placement of the light sources. It is possible to create quantum light sources in conventional three-dimensional materials such as diamond or silicon, but they cannot be precisely placed in these materials.
Deterministic Defects
The physicists then used a layer of the semiconductor molybdenum disulfide (MoS2) as the starting material, just three atoms thick. They irradiated this with a helium ion beam which they focused on a surface area of less than one nanometer.
In order to generate optically active defects, the desired quantum light sources, molybdenum or sulfur atoms are precisely hammered out of the layer. The imperfections are traps for so-called excitons, electron-hole pairs, which then emit the desired photons.
Technically, the new helium ion microscope at the Walter Schottky Institute’s Center for Nanotechnology and Nanomaterials, which can be used to irradiate such material with an unparalleled lateral resolution, was of central importance for this.
On The Road to New Light Sources
Together with theorists at TUM, the Max Planck Society, and the University of Bremen, the team developed a model which also describes the energy states observed at the imperfections in theory.
In the future, the researchers also want to create more complex light source patterns, in lateral two-dimensional lattice structures for example, in order to thus also research multi-exciton phenomena or exotic material properties.
This is the experimental gateway to a world which has long only been described in theory within the context of the so-called Bose-Hubbard model which seeks to account for complex processes in solids.
Quantum Sensors, Transistors and Secure Encryption
And there may be progress not only in theory, but also with regard to possible technological developments. Since the light sources always have the same underlying defect in the material, they are theoretically indistinguishable. This allows for applications which are based on the quantum-mechanical principle of entanglement.
“It is possible to integrate our quantum light sources very elegantly into photon circuits,” says Klein. “Owing to the high sensitivity, for example, it is possible to build quantum sensors for smartphones and develop extremely secure encryption technologies for data transmission.”
Suggested Items
I-Connect007 Editor’s Choice: Five Must-Reads for the Week
04/25/2025 | Nolan Johnson, I-Connect007I’m highlighting a discussion on the positive potential coming from the recent changes in global trade policy—from IPC’s Government Relations team, and from TTM CEO Tom Edman. In the realm of designers and purchasers realm, there’s news from Screaming Circuits and ASC/Sunstone Circuits to share. Finally, additive manufacturing and the release of CFX 2.0 highlight just some of the news coming to the shop floor as well.
UHDI Fundamentals: UHDI Drives Unique IoT Innovation in Farming
04/22/2025 | Anaya Vardya, American Standard CircuitsThe combination of UHDI's high-bandwidth capabilities and IoT's real-time data processing can lead to more efficient, immersive, and smarter IoT systems. This convergence of two revolutionary technologies is enabling quantum advancements in some very “unconventional” applications. The typical discussions around UHDI focus on our standard electronics industry market segments like milaero, medical, consumer electronics, etc. IoT is all about machines talking to other machines, machine learning, and artificial intelligence, but again, typically applied in our PCB and assembly operations.
ASC Sunstone Circuits and Screaming Circuits Partner to Launch Online Assembly Parts Ordering
04/21/2025 | ASC SunstoneIn a major step toward simplifying the PCB manufacturing and assembly process, ASC Sunstone Circuits and Screaming Circuits are proud to announce the launch of a new online assembly parts ordering feature, now available through Sunstone.com.
American Standard Circuits and ASC Sunstone to Exhibit at PCB East 2025
04/14/2025 | American Standard CircuitsAnaya Vardya, President, and CEO of American Standard Sunstone Circuits, has announced that his company will once again be exhibiting at PCB East 2025 to be held on April 30, 2025, at the Boxborough Regency Hotel and Conference Center in Boxborough, Massachusetts.
IDTechEx Explores Emerging Applications for PICs
04/11/2025 | IDTechExPhotonic integrated circuits are the optical equivalent of microchips, using semiconductor industry processes to shrink many photonic components down onto a piece of material often smaller than a human fingernail.