| Budget Amount *help |
¥224,640,000 (Direct Cost: ¥172,800,000、Indirect Cost: ¥51,840,000)
Fiscal Year 2012: ¥20,410,000 (Direct Cost: ¥15,700,000、Indirect Cost: ¥4,710,000)
Fiscal Year 2011: ¥24,440,000 (Direct Cost: ¥18,800,000、Indirect Cost: ¥5,640,000)
Fiscal Year 2010: ¥48,620,000 (Direct Cost: ¥37,400,000、Indirect Cost: ¥11,220,000)
Fiscal Year 2009: ¥94,640,000 (Direct Cost: ¥72,800,000、Indirect Cost: ¥21,840,000)
Fiscal Year 2008: ¥36,530,000 (Direct Cost: ¥28,100,000、Indirect Cost: ¥8,430,000)
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| Research Abstract |
We investigated quantum degenerate matter phases of photo-generated electrons and holes in semiconductor materials and explored and developed techniques to control and manipulate such systems. Major achievements include the successful observation of the Bose-Einstein phase transition of excitons created and confined in a three-dimensional trap in a bulk direct-gap semiconductor. In an attempt to further stabilize the condensate phase, an ultracold quantum degenerate gas of excitons was then created by cooling it down with a dilution refrigerator. Also, we developed an excitation scheme for the cold electron-hole system in diamond, a wide-gap indirect semiconductor. It led to the discovery of the polyexciton bound state in the low temperature regime, formed as a result of the suppression of electron-hole droplet formation. Furthermore, a high-order photon correlation acquisition system using a streak camera was developed as a method to measure the photon statistics in an ultrafast timescale. Using this, we detected an oscillation, induced by the relaxation oscillation phenomena, of the second-order correlation function for a vertical cavity surface emitting laser in the vicinity of the laser threshold. Moreover, we explored a new method to control material excitations using waveform-shaped pulses. We focused particularly on the conservation of quasi-angular momentum in Raman-type processes in crystals possessing three-fold rotational symmetries. As a result, an unrestrained control of magnon spin states and THz polarizations was demonstrated by shaping optical pulses as vector waves and thus regulating temporal characteristics of their polarization states.
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