Sunhee Lee

Exchange Interaction Calculation in Si-DQD

Exchange Interaction Calculation in Si-DQD Sunhee Lee, Hoon Ryu & Gerhard Klimeck

Objective:

  • Using NEMO 3-D, implement and investigate exchange splitting of 2-electron system of double dot system used for qubits
  • Find out relationship between inter-dot distance and exchange splitting

Approach

  • Use the spds* tight binding (TB) band model
  • Potential is modeled as a quadratic function
  • For initial cut, use Heitler-London approximation assuming that the coupling of the electron wavefunction is small
  • Compare with other analytical result, such as HL and Hund-Mulliken(HM) approximation

Results & Impact:

  • Depending on the inter-dot distance, the exchange splitting exponentially decays
  • Reasonable agreement with analytical solutions

Ongoing Work:

  • Self-consistent 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.