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半導体量子ドットにおけるカップリングされた電子スピンの一貫した操作
J R Petta1, A C Johnson, J M Taylor
1Department of Physics, Harvard University, Cambridge, MA 02138, USA.
Science (New York, N.Y.)
|September 6, 2005
まとめ
私たちは,電気パルスを用いて,ダブル量子ドット内の2電子のスピン状態を正確に制御することができました. この量子制御は,超微細な相互作用を克服し,1マイクロ秒を超えてコヒーレンス時間を大幅に延長しました.
科学分野:
- 量子コンピューティング
- 量子情報科学とは,量子情報科学である.
- 固体物理 固体物理学
背景:
- 量子システムは,計算を行うために正確な制御を必要とします.
- 量子ドットにおける2電子のスピン状態は,有望な量子ビットである.
- 超微細な相互作用は量子状態の相関性を制限する.
研究 の 目的:
- 2電子のスピン状態の一貫した制御を実証するために.
- これらのスピン状態のコヒーレンス時間を測定し,延長します.
- 超微細相互作用が量子相干性に与える影響を調査する.
主な方法:
- 交換相互作用の急速な電気制御を二重量子ドットで利用した.
- シングレットスピン状態の分離と再結合を使用して,時間測定を脱相する.
- ラビ振動とスピンエコーパルス配列を量子操作とコヒーレンス強化のために応用した.
主要な成果:
- 2電子のスピン状態の状態準備,コヒーレント操作,投影的読み取りを達成しました.
- 約10ナノ秒のスピン脱相時間 (T2*) を測定し,超精細相互作用によって制限されました.
- スピン・エコー配列を用いたラビ振動と抑制された脱相の実証.
- 2電子のスピン状態の相干時間を1マイクロ秒以上まで延長しました.
結論:
- 一貫した制御技術は,2電子のスピン状態を正確に操作することを可能にします.
- 超精細相互作用は,GaAsにおける相関性の主要な制限であるが,緩和できる.
- 1マイクロ秒を超える長いコヒーレンスタイムを達成し,高度な量子情報処理の道を開いた.
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