Qubit Physics

Almost all superconducting qubits are based on Josephson Junctions, combined with capacitors and inductors. Early superconducting qubits can be categorized as shown in the figure below:

▲ Early superconducting qubits are divided into three main types: Charge Qubit, Flux Qubit, and Phase Qubit. The simple conceptual differences lie in the primary methods of controlling the qubits (highlighted in yellow boxes in the figure):
\(\to\) (a) Controlled by voltage: Voltage alters the stored charge in the capacitor, referred to as a Charge Qubit.
\(\to\) (b) Controlled by magnetic flux: Magnetic flux alters the energy storage in the Josephson Junction, referred to as a Flux Qubit.
\(\to\) (c) Controlled by induced current: Induced current alters the phase of the Josephson Junction, referred to as a Phase Qubit.

Ref: 10.7498/aps.71.20211865

Originally written in Chinese by the author, these articles are translated into English to invite cross-language resonance.