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Automatic
Mapping of Semiconductor Quantum Dots
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Returning to interesting sample positions has never been easier : Yves Delley from the Quantum Photonics Group ( QPG ) at the ETH Zurich have – based on attocube positioners with resistive encoders – built a micro-photoluminescence ( PL ) setup and automated it to a great extent . They programmed a fully automated routine for raster-imaging a full sample of up to 4 x 4 mm ² as well as implemented an auto-focus routine . Once initiated , the positioners are moved frame-by-frame and a CCD camera takes images of the PL of their semiconductor quantum dot samples . Knowing the coordinates of all individual images , it is easy to put together a complete map of the sample ( see figure on the left ).
“ Now , we have to select the interesting dots , at which we want to take a closer look ”, says Yves Delley , the responsible project researcher at QPG and gags : “ Yet , in order to find the shortest route between all these quantum dots , we would need a quantum computer to solve this problem .”
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( Image kindly provided by Yves Delley , Quantum Photonics Group , ETH Zurich , Switzerland ) |
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3D g-Factor Mapping of Single Quantum Dots |
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Energy ( meV )
1.3732 1.3730 1.3728 1.3726 1.3724 1.3722 1.3720 1.3718 1.3716
45 ° tilt
0 1 2 3 4 5 6 7 8 9 10 Magnetic Field ( T )
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Energy ( meV )
0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6
0
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45 ° tilt
1 2 3 4 5 6 7 8 9 10
Magnetic Field ( T )
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A xyz linear positioning stack combined with a rotator was used in a novel fiber-based confocal microscope , dedicated for the investigation of certain nanostructures such as InGaAs quantum dots ( QDs ) using magneto-photoluminescence ( PL ). The specific arrangement of positioners enabled scientists in this experiment to tilt and rotate samples at low temperature with respect to a magnetic field of up to 10 T while maintaining focus on a single QD .
T . Kehoe , M . Ediger , R . T . Phillips , and M . Hopkinson , Rev . Sci . Instrum . 81 013906 ( 2010 ).
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