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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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