Exchange Interaction Calculation in SiDQD
Exchange Interaction Calculation in SiDQD 
Sunhee Lee, Hoon Ryu & Gerhard Klimeck 
Objective:
 Using NEMO 3D, implement and investigate exchange splitting of 2electron system of double dot system used for qubits
 Find out relationship between interdot distance and exchange splitting
Approach
 Use the spds* tight binding (TB) band model
 Potential is modeled as a quadratic function
 For initial cut, use HeitlerLondon approximation assuming that the coupling of the electron wavefunction is small
 Compare with other analytical result, such as HL and HundMulliken(HM) approximation
Results & Impact:
 Depending on the interdot distance, the exchange splitting exponentially decays
 Reasonable agreement with analytical solutions
Ongoing Work:
 Selfconsistent simulation with Configuration Interaction (CI) calculation

Device geometry for simulation
 Assumed 104.3x104.3x3.3nm3 Si structure (1.7MA) from (arxiv:0906.4793v2)
Results

Powerpoint slide as pdf, or as image below.