Researcher from Japan's National Institute of Advanced Industrial Science and Technology (AIST) have succeeded in the vapor-phase synthesis of a stack of nanometer-scale thin films of diamond using carbon isotopes 12C and 13C, which differ in mass. Electrons and holes were confined to a single material for the first time using the diamond stack.
Previously reported at Nextbigfuture is the work of the European company Element Six. Element Six created synthetic diamond with less carbon 13 isotope and more pure carbon 12, which enables longer quantum coherence times to be maintained longer. Note: Normally 1.07% is carbon 13 isotope. They have reduced this ratio by over three times.
Diamond is an insulating material normally, but it is also a semiconducting material, in which the resistivity is controlled to 16 orders of magnitude by adding impurities. One of excellent properties of diamond is that the thermal conductivity is 6 times as large as those of the widely adopted heat sink materials including copper. diamond is now a prospective material for quantum bits in future quantum computers. The Japanese and other research helps make room temperature quantum computation operation feasible; the lifetime of quantum bits is improving; and quantum entanglement, needed for enabling quantum calculation, is substantiated.
For practical device applications of diamond, even higher material quality is needed, and our challenges include the reduction of defects, epitaxial film growth on large-sized wafers, and control of electrons and holes. Furthermore, regarding the confinement of electrons and holes using isotopes, the lifetime of electrons and holes inside the isotopes, recombination at the homojunction interface, and mobility of electrons and holes must be evaluated in detail, and the data will be examined whether they can effectively be used to design quantum functional devices. The technology shall be developed horizontally, such as for creating 13C quantum bits.