Confluence of resonant laser excitation and bidirectional quantum-dot nuclear-spin polarization

被引：151

作者：

Latta, C. ^{[1
]}

Hoegele, A. ^{[1
]}

Zhao, Y. ^{[2
]}

Vamivakas, A. N. ^{[2
]}

Maletinsky, P. ^{[1
]}

Kroner, M. ^{[1
]}

Dreiser, J. ^{[1
]}

Carusotto, I. ^{[3
,4
]}

Badolato, A. ^{[5
]}

Schuh, D. ^{[6
]}

Wegscheider, W. ^{[6
]}

Atature, M. ^{[2
]}

Imamoglu, A. ^{[1
]}

机构：

[1] ETH, Inst Quantum Elect, CH-8093 Zurich, Switzerland

[2] Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England

[3] Univ Trent, CNR, INFM, BEC Crr, I-38050 Trento, Italy

[4] Univ Trent, Dipartimento Fis, I-38050 Trento, Italy

[5] Univ Rochester, Dept Phys & Astron, Rochester, NY 14627 USA

[6] Univ Regensburg, Inst Expt & Angew Phys, Regensburg, Germany

来源：

NATURE PHYSICS | 2009年 / 5卷 / 10期

基金：

瑞士国家科学基金会; 英国工程与自然科学研究理事会;

关键词：

STATE PREPARATION; ELECTRON-SPIN;

D O I：

10.1038/NPHYS1363

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

Resonant laser scattering along with photon correlation measurements established the atom-like character of quantum dots. Here, we show that for a wide range of experimental parameters it is impossible to isolate elementary quantum-dot excitations from a strong influence of nuclear spins; the absorption lineshapes at magnetic fields exceeding 1 T indicate that the nuclear spins get polarized by an amount that ensures locking of the quantum-dot resonance to the incident laser frequency. In stark contrast to earlier experiments, this nuclear-spin polarization is bidirectional, allowing the combined electron-nuclear-spin system to track the changes in laser frequency dynamically on both sides of the resonance. This unexpected feature stems from a competition between two spin-pumping processes that attempt to polarize nuclear spins in opposite directions. We find that the confluence of laser excitation and nuclear-spin polarization suppresses the fluctuations in resonant absorption. A master-equation analysis suggests narrowing of the nuclear-spin distribution, pointing to applications in quantum information processing.

引用

页码：758 / 763

页数：6

共 26 条

[1] Quantum-dot spin-state preparation with near-unity fidelity [J].