QUANTUM CONTROL FOR NOISE REDUCTION IN QUANTUM DOT QUBITS AND GATES

Abstract

Today in the era of computational advancements and classical computing methods are hitting hard physical limits of scaling down the transistors due to size of transistors are becoming comparable with atom size causing Quantum Mechanical effects like tunnelling of electrons getting dominating, rendering the working of transistor useless. But due to new radically new Quantum Technologies we can use these effects for our aid. In quantum technology the precision of controlling signal pulses is of utmost importance as slight change can cause change of state. Here we are trying to implement some algorithms to control state of Quantum Dot Qubit and Gates also to mitigate effects of relaxation and dephasing errors. To design a robust Quantum system, we are trying to implement GRAPE algorithm initially proposed for NMR or Nuclear Magnetic Resonance spectroscopy. Here, we will design control amplitudes of RF field to drive system to a certain desired state. CRAB and dCRAb are another Quantum Optimal Control algorithms that we are going study in this report which are gradient-less algorithms but are highly efficient in terms of iterations. This algorithm is proposed for multi-dimensional and time dependent Hamiltonian based quantum systems. Dynamical Decoupling is the most sought after algorithm in the industry as it has many application specific and experimentally deployable variants available that makes us to study it.