Spin state tomography of optically injected electrons in a semiconductor
Hideo Kosaka1, Takahiro Inagaki, Yoshiaki Rikitake
1Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan. kosaka@riec.tohoku.ac.jp
Nature
|February 6, 2009
Summary
We developed tomographic Kerr rotation, a new method to directly measure electron spin coherence. This technique enables spin state tomography for advanced quantum information technology applications.
Area of Science:
- Quantum Information Science
- Condensed Matter Physics
- Optics and Photonics
Background:
- Electron spin is crucial for quantum information technology, requiring coherent preparation and readout.
- Traditional Kerr rotation measures spin population but needs extra steps to infer spin coherence.
Purpose of the Study:
- To develop a technique for direct measurement of electron spin coherence.
- To enable spin projection measurements on arbitrary basis states.
- To achieve basis-independent preparation and readout of spin quantum states.
Main Methods:
- Generalizing the traditional Kerr rotation approach.
- Utilizing the transfer of light polarization coherence to electron spin coherence.
- Applying the tomographic Kerr rotation method to semiconductor quantum wells.
Main Results:
- Demonstrated direct measurement of electron spin coherence without spin manipulation.
- Showcased the transfer of polarization coherence from light to electron spin.
- Confirmed the technique's efficacy on precessing and non-precessing electrons in quantum wells.
Conclusions:
- Tomographic Kerr rotation enables direct, basis-independent measurement of electron spin coherence.
- This technique facilitates spin state tomography for quantum information applications.
- Provides a novel tool for spin quantum state preparation and readout in solid-state systems.
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