Controllability of Qubits
In the video, Jason talks about manipulating a qubit state with a magnetic field. Can you think of another way to bring a qubit to a higher energy level?
One possible way to manipulate qubits, is to shoot a photon (a light wave/particle) into the qubit system. The energy of the photon should match the energy gap between the higher energy state and the lower energy state to make the qubit transition possible. The photon will be absorbed, and the qubit will be in the higher energy state after the absorption.
Qubit manipulation with magnetic fields is mainly used in flux qubits, where the direction of the current in a loop can be reversed by applying an opposite magnetic field: