TY - JOUR
T1 - Spin state tomography of optically injected electrons in a semiconductor
AU - Kosaka, Hideo
AU - Inagaki, Takahiro
AU - Rikitake, Yoshiaki
AU - Imamura, Hiroshi
AU - Mitsumori, Yasuyoshi
AU - Edamatsu, Keiichi
N1 - Funding Information:
Acknowledgements This work was supported in part by the Strategic Information and Communications R & D Promotion Program (SCOPE No. 41402001) of the Ministry of Internal Affairs and Communications in Japan.
Copyright:
Copyright 2009 Elsevier B.V., All rights reserved.
PY - 2009/2/5
Y1 - 2009/2/5
N2 - Spin is a fundamental property of electrons, with an important role in information storage. For spin-based quantum information technology, preparation and read-out of the electron spin state are essential functions. Coherence of the spin state is a manifestation of its quantum nature, so both the preparation and read-out should be spin-coherent. However, the traditional spin measurement technique based on Kerr rotation, which measures spin population using the rotation of the reflected light polarization that is due to the magneto-optical Kerr effect, requires an extra step of spin manipulation or precession to infer the spin coherence. Here we describe a technique that generalizes the traditional Kerr rotation approach to enable us to measure the electron spin coherence directly without needing to manipulate the spin dynamics, which allows for a spin projection measurement on an arbitrary set of basis states. Because this technique enables spin state tomography, we call it tomographic Kerr rotation. We demonstrate that the polarization coherence of light is transferred to the spin coherence of electrons, and confirm this by applying the tomographic Kerr rotation method to semiconductor quantum wells with precessing and non-precessing electrons. Spin state transfer and tomography offers a tool for performing basis-independent preparation and read-out of a spin quantum state in a solid.
AB - Spin is a fundamental property of electrons, with an important role in information storage. For spin-based quantum information technology, preparation and read-out of the electron spin state are essential functions. Coherence of the spin state is a manifestation of its quantum nature, so both the preparation and read-out should be spin-coherent. However, the traditional spin measurement technique based on Kerr rotation, which measures spin population using the rotation of the reflected light polarization that is due to the magneto-optical Kerr effect, requires an extra step of spin manipulation or precession to infer the spin coherence. Here we describe a technique that generalizes the traditional Kerr rotation approach to enable us to measure the electron spin coherence directly without needing to manipulate the spin dynamics, which allows for a spin projection measurement on an arbitrary set of basis states. Because this technique enables spin state tomography, we call it tomographic Kerr rotation. We demonstrate that the polarization coherence of light is transferred to the spin coherence of electrons, and confirm this by applying the tomographic Kerr rotation method to semiconductor quantum wells with precessing and non-precessing electrons. Spin state transfer and tomography offers a tool for performing basis-independent preparation and read-out of a spin quantum state in a solid.
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U2 - 10.1038/nature07729
DO - 10.1038/nature07729
M3 - Article
C2 - 19194446
AN - SCOPUS:59649128294
VL - 457
SP - 702
EP - 705
JO - Nature
JF - Nature
SN - 0028-0836
IS - 7230
ER -