第37回 原研・兵県大合同コロキウム

日時: 平成20年2月19日(火) 16:00〜
Date and time: 19th Feb. (Tue.) 16:00〜
場所: SPring-8, 萌光館
Place: SPring-8, "HOUKOUKAN" seminar room
Title: Electric-field-driven nuclear spin control using diluted magnetic semiconductors
講演者: 赤井久純 氏 (大阪大学大学院理学研究科物理)
Speaker: Prof. Hisazumi Akai (Department of Physics, Osaka University)
Abstract:

One of the key-technologies required to realize a quantum computer that uses nuclear spins as its quantum bits is control of nuclear spins in nano-scale semiconductor devices. One way of achieving this control is electric-field-controlled NMR. This involves controlling the hyperfine coupling between electrons and the nuclear spin (the hyperfine field) by varying an electric field applied to the system. One practical implementation, already demonstrated experimentally, uses the edge states of a 2D electron gas. Another possibility, suggested by Kane, uses a gate voltage to deform the s-electron wave function at the nuclei 31P impurity in a Si host. The principle of this latter mechanism has been demonstrated theoretically in a simple model system but its effectiveness in real systems is not clear. In this talk, we propose implementing electric-field-controlled NMR by using a bias voltage to control the hole carrier density near the impurity. We use a heterostructure constructed from diluted magnetic semiconductors. The effect on NMR of a bias voltage on an (In,Mn,As)As/AlSb system is calculated using first-principles electronic structure methods. The calculations show that the hyperfine field at the antisite As are very sensitive to an external electric field. This technique can be used to control nuclear spins in quantum computer that uses nuclear spins as its quantum bits.