3.3.5 Quantum control and readout

Course subject(s) Module 3: Quantum Compiling and Quantum Dots

Now that you know how quantum dot qubits work it is time to learn how to operate them! In this video Menno will explain operations of readout, initialization and control on single and multi-qubits.

  • Two methods can be used to readout an electronic spin: Elzerman readout, based on an energy-dependent tunnelling process, and Pauli-spin blockade where tunneling is inhibited for certain spin configurations due to the Pauli exclusion principle.
  • Rabi rotations can be realized by applying an AC magnetic field at the Larmor frequency in a direction orthogonal to the static magnetic field. By controlling the phase of this field, one can change the rotation axis, obtaining universal single qubit control.
  • Instead of using a fast AC magnetic field, the most efficient method to drive a qubit is exploiting spin-orbit coupling. Rabi oscillations can be achieved by applying an AC electric field on resonance with the qubit energy.
  • One can exploit the exchange interaction between two qubits to make two-qubit gates by time evolution of the system. Alternatively, exchange interaction results in a change in resonance frequency and, by applying an AC magnetic field on resonance with this new frequency, one can achieve controlled rotations.
  • In a similar fashion, exchange-coupling between multiple qubits results in resonance frequency splitting. Driving at one of these frequencies results in a multi-qubit operation.
Creative Commons License
Fundamentals of Quantum Information by TU Delft OpenCourseWare is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Based on a work at https://online-learning.tudelft.nl/courses/fundamentals-of-quantum-information/ /
Back to top