Hiromitsu Kato

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The negatively charged nitrogen-vacancy (NV) centre exhibits outstanding optical and spin properties and thus is very attractive for applications in quantum optics. Up to now an active control of the charge state of near-surface NV centres is difficult and the centres switch in an uncontrolled way between different charge states. In this work, we(More)
Service systems in public spaces are now being developed by employing ubiquitous computers in these spaces. Such systems must provide services to end users with a wide range of motivations, including unmotivated users who do not actively use the available services. Context-awareness to support these users is thus an important requirement for this kind of(More)
Much business and technical attention is being paid to the potential for new services in a ubiquitous computing environment. One of the probable features of these services is 'context-awareness', which is made possible by using information from the physical environmental through sensors. This paper provides an overview of the opportunities for new services(More)
The electric field inside semiconductor devices is a key physical parameter that determines the properties of the devices. However, techniques based on scanning probe microscopy are limited to sensing at the surface only. Here, we demonstrate the direct sensing of the internal electric field in diamond power devices using single nitrogen-vacancy (NV)(More)
We fabricated inversion channel diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) with normally off characteristics. At present, Si MOSFETs and insulated gate bipolar transistors (IGBTs) with inversion channels are widely used because of their high controllability of electric power and high tolerance. Although a diamond semiconductor is(More)
Bilayer graphene was synthesized at low temperature using surface wave microwave plasma techniques where poly(methyl metacrylate) (PMMA) and methane (CH4) were used as carbon sources. Temperature-dependent Hall effect measurements were carried out in a helium atmosphere. Sheet resistance, sheet carrier density and mobility showed weak temperature dependence(More)
We propose a method to retrieve trustworthy information from a word-of-mouth community space that could include inappropriate information. In a ubiquitous information society, high anonymity could cause some problems concerning human rights infringements, such as slander and invasion of privacy. On the other hand, unless anonymity is guaranteed at a certain(More)
OVERVIEW: To supply public infrastructure systems that keep pace with changes in society, Hitachi is promoting the symbiosis autonomous decentralized concept, a system concept for achieving the sustainability of society as a whole while treating change as the norm. To turn this concept into reality, Hitachi is developing system development technologies that(More)