Nanotechnology is a technique for fabricating very fine structures on a nanometer (nm) scale (nano is the reciprocal of 1,000,000,000). NTTBRL has certain advantages in terms of nanotechnology research through the introduction of state-of-the-art electron beam lithography instruments and long experience in the field. We fabricate many samples including NEMS/MEMS devices, photonic crystals, quantum effect devices, which support our cutting edge research results.
The single-electron device, which operates based on single electrons, is advantageous because it consumes less power than a conventional LSI. NTT-BRL has been engaged in work on single-electron devices because there is always a demand for reduced power consumption. We also aim at developing new applications for these devices including as extremely sensitive sensors and current standard devices.
A photonic crystal is a material with a structure whose refractive index changes periodically. A photonic band gap, which is an area that prohibits the transmission of light, is formed in a photonic crystal using a similar principle to that behind the formation of a band structure in semiconductor crystals. Order made photonic crystals can be fabricated by employing state-of-the-art nanotechnology, which is the key to proposing and demonstrating various new methods for controlling light.
A quantum bit is a state formed by the combination of two quantum states. This is the minimum unit of quantum information and is called a qubit. Compared with a bit, which represents one of the two states (0 or 1) used in current computers, the qubit can represent an infinite number of states depending on the degree of the overlap between two quantum states. NTTBRL is studying various qubits formed of superconducting flux, an electron charge, neutral atoms and excitons.
By using a probe called a cantilever, a scanning probe microscope provides 2D mapping of the interaction between the cantilever tip and a surface. Various parameters including van der Waals force and frictional force, as well as tunnel currents and electric fields, can be detected by choosing an appropriate cantilever and operating mode for the microscope. The microscope’s greatest advantage is its atomic to molecular scale resolution. It also works in a variety of environments including in a vacuum, in air, and in a solution.
Q.I.T. (Quantum information technology) is a new field of research that utilizes quantum mechanics in information processing. This includes quantum computing and quantum cryptography. The bases for developing the research are a nano structure fabrication technique and a highly sensitive measurement technique. By their continuous efforts to investigate these techniques, NTTBRL is promoting research that is the prerequisite for future information technology.
An atom chip is a device that can trap neutral atoms in the vicinity of a solid surface. The atoms are normally trapped by using magnetic fields that are induced by an electric circuit fabricated on the solid surface. NTTBRL has succeeded in fabricating the persistent supercurrent atom chip that provides noise-free environment advantageous for long-term coherence.
A pair of photons that has a quantum correlation is called an entangled photon pair. The characteristic feature of these entangled photons is that the quantum state of one photon can be automatically determined by observing the quantum state of the other. NTTBRL is engaged in the fabrication of devices for generating entangled photons and in investigating the use of entangled photons in quantum information technology.
Although diamonds are well known as jewelry, they also possess advantages as an electric material. They have high-speed device applications (several thousand times faster than conventional silicon devices) and provide stable device operation in severe environments because of their excellent heat resistivity. NTTBRL is working on diamond device fabrication and the growth of high-quality diamond thin film.
A graphene sheet is an atomic layer sheet extracted from graphite. If it is single layered, it is called a Single Wall carbon NanoTube (SWNT), if it is multilayered it is called a Multi Wall carbon NanoTube (MWNT). Depending on the wrapping angle (called chirality), CNT can be a metal or semiconductor. NTTBRL is working to establish a method for synthesizing identical CNTs for future device applications.
Nanobio is a newly proposed research field that combines nanotechnology and biotechnology. It includes research designed to obtain new biological knowledge using nanotechnology methods and for applying biological principles to device fabrication and operation. NTTBRL aims to develop a unique "nanobio device" that combines biomolecule functions and electronic nanodevices for use as future communication technology devices.
NEMS/MEMS stands for Nanometer (Micrometer) Electric Mechanical Systems. These systems combine electric devices with mechanical devices. NTTBRL is undertaking the design and fabrication of NEMS using our original crystal growth technique. Our goal is to be pioneers in the new field of NEMS research.
Spin is a kind of angular momentum that is possessed by a quantum particle. It is one of the degrees of freedom used to distinguish quantum particles. Normally, spin means electron spin, which is mainly related to magnetism in our daily lives. An atomic nucleus also possesses spin called isospin. NTTBRL aims to develop quantum devices that use these spins and isospins.
Quantum mechanics is a theory that describes phenomena related to microscopic components of matter such as electrons and nuclei. For instance, the wave-particle duality in electrons and photons, the uncertainty principle, and wave function collapse are all explained in terms of quantum mechanics. NTTBRL is mainly working on the use of quantum phenomena in new generation devices, as well as contributing to the scientific community through experimental demonstrations of quantum mechanics.
Current electronic devices use electrons as charge carriers. In addition to a charge, an electron has another degree of freedom called spin. Spintronics is the research field whose goal is to control this spin and use it for electronic devices. NTTBRL aims at developing techniques to control and detect single spin, and at realizing electronic devices based on this new principle of device operation.
A quantum computer embodies a new computer processing method based on a quantum state. This is in contrast to conventional computing, which is based on digital signals (0 and 1). This method enables large-scale parallel processing that could never be achieved with classical computing. NTTBRL is exploring various quantum bits, and is contributing to the realization of the quantum computer by establishing the technology needed to link multiple qubits.
Quantum cryptography systems are based on the quantum mechanics principle whereby "quantum states are destroyed by observation". Once a quantum computer has been realized, classical cryptography systems will be easily broken; but quantum cryptography is absolutely safe. Of several possible quantum cryptography systems, NTTBRL has proposed a unique differential-phase-shift quantum-key-distribution system and is undertaking research for its future realization.
When an electron and a hole are generated by excitation in a semiconductor and are then coupled by a Coulomb interaction, the resulting pair is called an exciton. An exciton generated within a semiconductor quantum dot possesses discrete energy levels. NTTBRL is studying the exciton as a candidate for a qubit when generated by the excitation provided by a coherent light source.
Wide-gap semiconductors are semiconductor materials with a high bandgap, usually exceeding ** eV. NTTBRL is studying such materials as nitrides, silicon carbide and diamond. We are investigating the fundamental technologies related to the growth of these materials, and we plan to develop devices including ultraviolet wavelength light emitting diodes and high-frequency power devices.
A graphene sheet is an atomic layer sheet extracted from graphite. Its structure is a honeycomb lattice of hexagonal benzene. It is an allotrope of diamond, carbon nanotube and fullerene. Graphene has very high carrier mobility (~100,000 cm2/Vs) and is expected to be employed as a post silicon material.
Self-organization is a process for forming an organized structure spontaneously without any specific external stimuli. This appears in various areas, including the formation of giant structures by accumulating molecules and the growth of crystals at specific positions on crystal surfaces.