Quantum computer has a great attention all over the world, several attempts to construct it by supposing a theoretical or experimental model for qubit which is the basic unit of quantum computer. Qubit is formed from two level physical system, So, semiconductor quantum dot is suitable for qubit where qubit state formed from superposition between two spin states , silicon (Si) quantum dot is one of suitable system for qubit and quantum logic gate because of its long coherence time.
In this work, we study theoretical model of quantum dots from silicon (Si) which coupling through superposition and entanglement mechanism to form quantum logic gate. we have investigated magnetic field effect on exchange interaction by using two approximate methods Hund – Mullikan (HM) and Hitler – London (LH) for calculation and evaluation of the exchange interaction coupling , also study the influence of inter – dots distance on the exchange coupling. From investigation of exchange interaction, silicon quantum dots is the best suitable for quantum logic gate.