We are studying devices using ultrahigh-frequency integrated circuits up to the terahertz band, which has properties between radio waves and light, as well as sensors and communication systems that use these circuits. By creating ultrahigh-frequency devices with silicon CMOS integrated circuits suitable for mass production, we make it easy for anyone to use devices with innovative performance. The sixth generation (6G), which will follow the fifth-generation communications (so-called 5G) that began in 2020, is expected to include wireless communications in the 300 GHz band using the terahertz band. In 2019, we have realized the world's first single-chip CMOS transceiver capable of 80 gigabits per second wireless communication using the 300 GHz band.
The realization of an innovative device is the result of a steady process of improving the elemental circuits that make it up. The technology used in the past is not always truly the best method. We realize innovative performance by going back to basic theory and the laws of physics, considering why we do what we do, creating devices, and evaluating them.

We work on radio-frequency (RF) integrated circuit design, measurement, and device modeling. Computer-aided design (CAD) of analog and RF circuits has not been as successful as for digital circuits. We are interested in gaining design insights that will benefit practicing circuit designers and development of RF CAD. We also look at characterization and modeling of devices up to millimeter-wave frequencies. We are also involved in the development of device noise measurement solutions covering high frequencies and low temperatures.

The Research Institute for Nanodevices was founded, aiming to develop the fundamental technologies necessary to achieve global excellence in electronic and bio integrated sciences for preventive medicine and ubiquitous diagnoses on early stages of illnesses in the future advanced medical-care society beyond the present information society. The institute is equipped with two super clean rooms (R&D CMOS fabs), and here researchers could fabricate their own integrated devices. The research field includes Nano-Integration, Integrated Systems, Molecular Bioinformation and Nanomedicine. The Research Institute for Nanodevices is selected as one of 1. MEXT’s Research Center for Bio Medical Engineering, 2. MEXT’s Advanced Research Infrastructure for Materials and Nanotechnology (ARIM), 3. METI’s J-Innovation HUB.

Currently, transistors in electronic devices used in computers and smartphones are getting smaller, reaching the level of several tens of nanometers. A nanometer is one millionth of a millimeter (10^-9m).
Our group is conducting research on nanotechnology. Nanotechnology is a technology that fabricates and processes nanometer-sized materials and utilizes their specific physical properties. In particular, we are studying nanotechnology and nanoscience for future electronic devices with the keywords of "surface science", "self-assembly", and "nanomaterials". Through the research work, the students can obtain ability to work on technological development in various fields including electronic devices development.

(Prof. Kadoya)
[1] Development of high performance THz wave emitter and detector
[2] Research on light wave manipulation by meta-surface

Quantum optics and quantum information (Prof. Hofmann)
At the photon level, light exhibits quantum properties that exceed the classical limit. Such non-classical properties of light can be used to realize a variety of advanced quantum information technologies. Theoretical knowledge is indispensable to understand the possibilities of quantum information. In our ongoing research, we use the mathematics of the Hilbert space formalism to analyze measurement statistics and to identify the limits of control for the quantum states of light and matter in order to clarify the operating principles of recent quantum technologies.
[3] Non-local quantum correlations in entangled states
Correlations between two quantum systems can be so strong that they cannot be explained by any combination of local values for these properties. A quantum state with such a correlation is called an entangled state. The theoretical investiation of the non-classical features of entanglement are the topic of this research.
[4] Research on quantum measurement
Due to the uncertainty principle, quantum states cannot be explained by the statistics observed in only one type of measurement. We investigate the trade-off between measurement uncertainties and the dynamics of measurement interactions in order to understand and control the non-classical features of quantum statistics and quantum information.
[5] Multi-photon interferometry
Because of their quantum correlations, multi-photon states can be used to achieve very high phase sensitivities in optical interferometers. In our research we analyze the statistics of multi photon interference using the Hilbert space algebra of multi photon states to identify the
fundamental principles that make extreme sensitivity possible.

(Prof. Tominaga)
My research theme is the development of novel optical and terahertz devices based on the crystal growth of dilute bismide III-V compound semiconductors. I also explore the novel crystal growth technique for compound semiconductors using marine photosynthetic bacteria.

In nanometer-scale systems made of semiconductors and/or metals, an electron exhibits unusual behaviors that reflect its wave-particle duality. A nano-sized structure also strongly affects light. For example, light in a periodic nanostructure shows a band structure similar to that of electrons in a crystal. We are conducting theoretical research on the quantum properties of electrons and light in such small systems. We explore and realize functional devices based on new operating principles by using quantum effects, such as tunneling and superconductivity, and topological band structures of waves in periodic structures.

Our laboratory performs research on “Semiconductor” that will support a future society. We aim to generate new value by developing unique technologies through electronic engineering.
Research that we are involved in includes innovative plasma technologies for electronic device fabrication using atmospheric-pressure thermal plasma jets.
We have also developed a technology to transfer thin single-crystal silicon layers using the meniscus force of water to a PET substrate that is used in PET bottles. We have succeeded in using this technology to create flexible electronic circuits that serve as flexible MOS transistors and CMOS inverters that possess the highest performance in the world.
We look forward to working with everyone to create a better future.