At TATE LABO, we focus on the development of innovative optical information processing devices and systems that operate on a macro scale. Our work is based on advanced knowledge and experimental techniques for designing and optimizing optical quantum systems at micro-scale, spanning dimensions from microns to nanometers, under the guiding concept of "light × nano × information". Through these research activities, we aim to promote human resources with the unique qualities of both specialists and generalists. These individuals will be trained to address challenges across scales―from nano to macro, from fundamental research to practical applications, and from foundational physics to real-world solutions―by integrating and comprehensively addressing diverse needs and opportunities.

light × nano × information(@TATE LABO)

Optical information processing based on quantum dot engineering

Semiconductor nano-microparticles, known as "quantum dots"―for which the 2023 Nobel Prize in Chemistry was awarded―are more than just materials that emit fluorescence. They constitute an attractive optical material with diverse properties depending on their composition, dimensions, arrangement, and environment. In this research line, we aim to demonstrate and implement various optical computing approaches, focusing on micro-optical neural networks that exploit quantum dots as building blocks

Optical computing architecture@TATE-LABO

We will create a neural network, a typical execution model in machine learning, using a dispersed structure of fluorescent nanoparticles and quantum dots. The energy of the localized field excited inside a quantum dot network by an optical signal input from the outside exhibits various behaviors, depending on the network structure, such as immediate emission as fluorescence or emission after autonomously propagating in the network. Consequently, the fluorescence output from the entire quantum dot network does not show a simple linear relationship with the input but instead, shows a nonlinear input−output relationship essential for operation as a neural network. In this study, we will evaluate the performance of a quantum dot network by measuring the ultrafast fluorescence phenomenon caused by the incidence of an ultrashort pulse laser on the prototyped quantum dot network at a single-photon level. We are also working on demonstrating machine learning based on the obtained optical input−output relationship.

Nano-optical metrics to ensure safety / security of semiconductor IC chips

In today's world, where the number of digital devices continues to grow exponentially, the development and deployment of security technologies to safeguard individual devices has become an urgent research priority. In this research line, we aim to develop "nano-optical metrics" to establish a new security hierarchy based on advanced optical technology, specifically targeting the vast array of micro-IC chips that are as ubiquitous as water and air in modern society.

Nano-optical metrics@TATE-LABO

We propose to utilize the characteristic optical response of unclonable "micro-optical markers" applied to IC chips as unique identification information for each chip for individual authentication. The characteristics of the "micro-optical markers" vary widely depending on their dimensions, shape, surrounding structure, and the composition of the fluorescent materials they contain, so minute "fluctuations" during production can produce diverse optical responses, or identification information. In this research, we have demonstrated that the oscillation spectra exhibited by large quantities of "micro-optical markers" mass-produced using an inkjet printing method show high individuality.

Photon breeding devices by adjusting nano-quantum systems

Photon breeding is an innovative approach to designing and fabricating light source devices, in which photons tailored to the specific characteristics of a micro-scale physical system are generated by precisely tuning that system. In this research, we aim to harness the unique effects of photon breeding to develop advanced optical control devices, enabling unprecedented optical functionalities and exploring new application fields.

Optical computing architecture@TATE-LABO

We have used a dopant distribution optimization technique called "DPP annealing" for Al-ion-doped SiC materials to adjust the spatial distribution of Al ions in the SiC material so that it functions as an effective photon source. As a result, we have demonstrated for the first time that the optical modulation characteristics of the device are strongly dependent on the conditions during "annealing," and that a huge modulation effect is only observed for optical inputs that match those conditions. Optical modulation with such characteristics is unprecedented, and we are currently working to elucidate its functional mechanism and to develop application systems that could only be realized with this device.

E-mail: tate[at]ed.kyushu-u.ac.jp