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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:5
UID:UW-Physics-Event-4627
DTSTART:20170925T150000Z
DURATION:PT1H0M0S
DTSTAMP:20260416T045436Z
LAST-MODIFIED:20170921T120858Z
LOCATION:5310 Chamberlin Hall
SUMMARY:Spin-orbit interaction at the level of single electrons\, R. G
 . Herb Condensed Matter Seminar\, Dr. Andrea Hofmann\, ETH Zurich
DESCRIPTION:<br>
\nWe measure the anisotropy of spin-orbit interaction
  (SOI) using real-time charge detection of single electrons tunneling 
 between different states of GaAs/AlGaAs-based double quantum dots (DQD
 s). The strength of the SOI depends on the crystallographic direction 
 of the electron tunneling\, and on the relative alignment between the 
 tunneling direction and the spin quantization axis. In the DQD\, the t
 unneling direction is defined by the main axis of the device\, and the
  spin quantization axis is chosen by the direction of an external in-p
 lane magnetic field. This set-up allows us to control the strength of 
 the spin-orbit interaction and leads to spin lifetimes of 10 s.<br>
\n
 <br>
\nWe fabricate two DQDs on a GaAs heterostructure\, one with its 
 main axis along the [110] crystal axis\, and another one with the main
  axis rotated by 90 degrees\, i.e. along [-110]. By applying suitable 
 gate voltages to metallic top-gates\, each DQD is brought into a confi
 guration where two electrons reside in the device\, and tunneling to t
 he source and drain is suppressed. Using a charge detector\, we distin
 guish between two resonant charge states: one state where both electro
 ns reside in the right quantum dot\, (0\,2)\, and one state where each
  dot is occupied by a single electron\, (1\,1). We argue that in this 
 configuration\, the Pauli spin blockade can be used to measure the str
 ength of the spin--orbit interaction experienced by tunneling electron
 s.<br>
\n<br>
\nWe use the two DQDs for measuring the different streng
 ths of the SOI experienced by electrons moving along distinct crystall
 ographic axes. We find that the SOI induces spin-flips for electrons m
 oving along [110]\, and that the SOI vanishes for an electron moving a
 long [-110]. For a given tunneling direction\, we vary the strength of
  the experienced SOI by changing the alignment between the tunneling d
 irection and spin-quantization axis by means of rotating the direction
  of the applied in-plane field. We find a sinusoidal dependence on the
  relative angle between the two directions.<br>
\n<br>
\nA high magnet
 ic field facilitates suppression of incoherent spin-relaxation process
 es within single dots. We measure the anisotropy of spin-flip tunnelin
 g rates between two energetically resonant quantum states in this sett
 ing and find that the spin--orbit interaction can be turned from on to
  almost completely off. 
URL:https://www.physics.wisc.edu/events/?id=4627
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