Tokyo Institute of Technology

About: Tokyo Institute of Technology is a education organization based out in Tokyo, Tôkyô, Japan. It is known for research contribution in the topics: Catalysis & Thin film. The organization has 46775 authors who have published 101656 publications receiving 2357893 citations. The organization is also known as: Tokyo Tech & Tokodai.

Wide-span optical frequency comb generator for accurate optical frequency difference measurement

Abstract: An optical frequency comb (OFC) generator was realized for accurate optical frequency difference measurement of 1.5 mu m wavelength semiconductor lasers by using a high frequency LiNbO/sub 3/ electrooptic phase modulator which was installed in a Fabry-Perot cavity. It was confirmed that the span of the OFC was wider than 4 THz. By using semiconductor lasers whose spectrum linewidths were narrowed to 1 kHz and a sensitive optical balanced-mixer-receiver for measuring beat signal between the sideband of the comb and the laser, we demonstrated a frequency difference measurement up to 0.5 THz with a signal-to-noise ratio higher than 61 dB, and a heterodyne optical phase locking with a heterodyne frequency of 0.5 THz in which the residual phase error variance was less than 0.01 rad/sup 2/. The maximum measurable frequency difference, which was defined as the sideband frequency with the signal-to-noise ratio of 0 dB, was estimated to be 4 THz. >

Photocatalytic reduction of CO2 using metal complexes

Abstract: Developing photocatalytic systems for CO 2 reduction will provide useful and energy-rich compounds and would be one of the most important focuses in the field of “artificial photosynthesis” and “solar fuels”. Such studies have been conducted in the past three decades from the perspective of basic science and for solving the shortage of fossil resources, which include both energy and carbon sources. More recently, focus has been placed on the mitigation of global warming through the reduction of atmospheric CO 2 . This review summarizes the enormous body of reported literature in this field, particularly studies that describe photocatalytic systems that use transition metal complexes as key players, i.e., as catalysts (Cat) and/or photosensitizers (PS). In addition, we briefly describe the evaluation of various photocatalytic systems, especially the performance of reductants (D) and solvents. Furthermore, we analyze the types of photocatalytic systems and classify each component in these systems according to their role: (1) PS, (2) Cat for CO 2 reduction catalysts, and (3) D. Briefly, we summarize the important features of each component and provide typical examples. The next section discusses the photocatalytic abilities of each of the three categories of photocatalytic systems: multicomponent systems comprising PS and Cat, supramolecular photocatalysts comprising a multinuclear complex, and hybrid systems constructed with metal-complex photocatalysts and inorganic materials, such as semiconductors or electrodes.

Molecular evidence from retroposons that whales form a clade within even-toed ungulates

Abstract: The origin of whales and their transition from terrestrial life to a fully aquatic existence has been studied in depth. Palaeontological1,2, morphological3 and molecular studies4,5,6,7 suggest that the order Cetacea (whales, dolphins and porpoises) is more closely related to the order Artiodactyla (even-toed ungulates, including cows, camels and pigs) than to other ungulate orders. The traditional view that the order Artiodactyla is monophyletic has been challenged by molecular analyses of variations in mitochondrial and nuclear DNA5,6,7. We have characterized two families of short interspersed elements (SINEs) that were present exclusively in the genomes of whales, ruminants and hippopotamuses, but not in those of camels and pigs. We made an extensive survey of retropositional events that might have occurred during the divergence of whales and even-toed ungulates. We have characterized nine retropositional events of a SINE unit, each of which provides phylogenetic resolution of the relationships among whales, ruminants, hippopotamuses and pigs. Our data provide evidence that whales, ruminants and hippopotamuses form a monophyletic group.

A >99.9%-fidelity quantum-dot spin qubit with coherence limited by charge noise

Abstract: Recent advances towards spin-based quantum computation have been primarily fuelled by elaborate isolation from noise sources, such as surrounding nuclear spins and spin-electric susceptibility, to extend spin coherence. In the meanwhile, addressable single-spin and spin-spin manipulations in multiple-qubit systems will necessitate sizable spin-electric coupling. Given background charge fluctuation in nanostructures, however, its compatibility with enhanced coherence should be crucially questioned. Here we realise a single-electron spin qubit with isotopically-enriched phase coherence time (20 microseconds) and fast electrical control speed (up to 30 MHz) mediated by extrinsic spin-electric coupling. Using rapid spin rotations, we reveal that the free-evolution dephasing is caused by charge (instead of conventional magnetic) noise featured by a 1/f spectrum over seven decades of frequency. The qubit nevertheless exhibits superior performance with single-qubit gate fidelities exceeding 99.9% on average. Our work strongly suggests that designing artificial spin-electric coupling with account taken of charge noise is a promising route to large-scale spin-qubit systems having fault-tolerant controllability.

Fine Design of Photoredox Systems for Catalytic Fluoromethylation of Carbon–Carbon Multiple Bonds

Abstract: ConspectusTrifluoromethyl (CF3) and difluoromethyl (CF2H) groups are versatile structural motifs, especially in the fields of pharmaceuticals and agrochemicals. Thus, the development of new protocols for tri- and difluoromethylation of various skeletons has become a vital subject to be studied in the field of synthetic organic chemistry. For the past decades, a variety of fluoromethylating reagents have been developed. In particular, bench-stable and easy-to-use electrophilic fluoromethylating reagents such as the Umemoto, Yagupolskii–Umemoto, Togni, and Hu reagents serve as excellent fluoromethyl sources for ionic and carbenoid reactions. Importantly, the action of catalysis has become a promising strategy for developing new fluoromethylations.For the past several years, photoredox catalysis has emerged as a useful tool for radical reactions through visible-light-induced single-electron-transfer (SET) processes. Commonly used photocatalysts such as [Ru(bpy)3]2+ and fac-[Ir(ppy)3] (bpy = 2,2′-bipyridine; ...