Controll of the nuclear spin of (In,Al)As/(Al,Ga)As quantum dots
When I grew semiconductor quantum dots using molecular beam epitaxy at the first time, the obtained specimen showed remarkable luminescence (because of beginner’s luck?). Then I observed the spectrum of single quantum dot of the specimen (Thanks to Sou, Nakata and Hirose of Fujitsu Labs). In the course of magneto-optical measurement, I incidentally observed the bistable phenomenon in formation process of nuclear spin polarization (I should not say incidentally.). I was glad without the survey of preceding research. The results were appeared on the cover of the proceedings of QD2008 and the cover of Butsuri.
Wavelength control of luminescence from InAs/(Al)GaAs quantum dots grown with In flush
I controlled wavelength of luminescence based on the idea get through the booting of new molecular beam epitaxy equipment. I enjoyed observations of change as is my intention; later I found it was naturally. When I grown multilayer-coupled quantum dots, the quantum dots were formed at earlier time than expectation in the upper layer. This shows surface segregation of In when In flush is incomplete. I repeated the cycle: grew in a clean room at early morning, took out the grown sample from equipment at evening, set it photoluminescence cryostat, evacuated and cooled, set wafers and evacuated for tomorrow growth at the same time, measured photoluminescence spectrum in midnight, and grew at early morning. It was when I was young. Mister Toriumi (technician) asked “Will you grow tomorrow?” I replied “Yes!” powerfully. I thank his work from early morning, and don’t forget his technician’s spirit.
Spin relaxation of exciton in nanowire quantum dots
This is phase relaxation and polarization relaxation of spin of exciton in InAs quantum dots in the middle of a InP nanowire. I determined phase relaxation from first order photon correlation signal, and polarization relaxation from random polarization component identified all polarization measurement. I enjoyed determining of change in phase relaxation time obeying so-called “Kubo theory”, and identification of Stokes vector using Muller calculation. BAP process has an effect on polarization relaxation. The sample was interesting because it was mixture of zincblende and wurzite structure. It showed remarkable luminescence, this is important for experiments. I was planning further measurement. But, when I set the sample to a cryostat, a scratch was on the sample surface. I observed the sample with a microscope. Nanowires were scraped off. R. I. P.— I decided not to hunt who did it. Teachings: Don’t trust others.
Quantum logic-gate using triple-coupled quantum dot system
When I was a student, “Anything at all, think up quantum gate using quantum dots” is my theme. Because I am short of knowledge and am not afraid of anything, I could design original gate. In those days, no book about quantum information and quantum processing was published. Then I know pleasure thinking what is not written in books. I thought this is research at that time, and want to believe so now. Someone asked me “Is your research experiment or theory?” I replied in a cool way “My research is design.”