Overview of Research in Laboratories

Materials Science Laboratory

Hiroki Hibino
   This laboratory aims at contributing to progress in materials science and revolutionizing information communication technology by creating new materials and functions through materials design at the atomic and molecular levels.
This laboratory consists of three research groups investigating a wide range of materials such as nitride semiconductors, graphene, superconductors, and biological molecules. We are conducting innovative materials research based on the technologies of growing high-quality thin films and precisely measuring the structure and physical properties of materials.
   This year, we succeeded in clarifying microscopic state changes during the annealing treatment which induces superconductivity in undoped cuprates so far believed as insulators and growing single-crystal cubic BN thin film on diamond and single-layer hexagonal BN on Co films, respectively. We also succeeded in developing new sensing fabric "hitoe", which enables to acquire biomedical signals by simply wearing the clothes, in collaboration with Toray Industries, Inc.

Physical Science Laboratory

Akira Fujiwara
   The aim of this laboratory is to develop semiconductor- and superconductor-based solid- state devices, which will have a revolutionary impact on future communication and information technologies. Utilizing high-quality crystal growth techniques and nanolithography techniques we have developed, research groups in our laboratory are working on nanodevices, quantum information processing devices, and high-sensitivity sensors based on new degrees of freedom such as single electrons, mechanical oscillations, quantum coherent states, and spins.
   This year we succeeded in realizing phonon lasing in an electromechanical resonator and coherent phonon manipulation in coupled mechanical resonators. We also demonstrated storage and readout of quantum states in a superconductor/diamond hybrid system. Progress was made in the research on topological insulating phase in InAs/GaSb heterostructures, accuracy evaluation of single-electron transfer, FET sensors with a resonance circuit, and gate overlapped InAs nanowire FETs.

Optical Science Laboratory

Tetsuomi Sogawa
   This laboratory aims for the development of core-technologies that will innovate on optical communications and optical signal processing, and seeks fundamental scientific progresses.
   The groups in our laboratory are working for the quantum state control by very weak light, the search for intriguing phenomena using very intensive and short pulse light, and control of optical properties by using photonic crystals and ultrasonic techniques, based on unique properties of semiconductor nanostructures such as quantum dots and nanowires.
   In this year, we achieved an on-chip single photon buffer by using a coupled resonator optical waveguide based on silicon photonic crystal cavities. We examined the long-term operation performance of a long-distance (90 km) differential phase shift key distribution service using a test-bed optical network in the Tokyo metropolitan area. We also proposed that a very high-fidelity entangled cluster state can be formed with a combination of laser irradiation and intensity tuning. In addition, we have successfully demonstrated control of excitonic optical properties in quantum dots by using coherent phonons and generation of an isolated attosecond pulse in Carbon K-edge (284 eV) region with a double optical gating method.

Nanophotonics Center

Masaya Notomi
   Nanophotonics Center (NPC) was established in April 2012 by several research groups involved with nanophotonics in Basic Research Laboratories, Photonics Laboratories, and Microsystem Integration Laboratories in NTT. We are aiming for developing a full-fledged large-scale photonic integration technology by which we will be able to densely integrate a large number of nano-scale photonic devices with various functions in a single chip. Furthermore, we are targeting extreme reduction of the consumption energy for photonic information processing by taking advantage of the nanophotonics technology.
   This year, we demonstrated a novel way to form a nanocavity by placing a III/V semiconductor nanowire on a Si photonic crystal, and we also realized a novel multi-layer waveguide on Si for mode-division multiplexing. As regards nanophotonic device research, we have realized a novel nano-photodetector based on photonic crystals, and succeeded in largely reducing the operation energy-per-bit of electrically-pumped nanolasers. In addition, we achieved accelerated spontaneous emission rate of quantum wells in photonic crystal nanocavities.