Designing for Superconducting Qubit Circuits
Application Notes
The advantage of quantum computing stems from its unique exponential scaling in computational capability with the increased number of quantum bits (qubits), which enables quantum computers to tackle problems far beyond the reach of classical ones. In recent years, researchers have demonstrated various quantum computing platforms as candidates to scale up quantum computing operations. One of these platforms, the superconducting qubits, which operate at milli-Kelvin temperature, has shown great promise for their robustness, scalability, and manufacturability.
Qubits can be envisioned as an almost isolated two-level quantum system. Unlike classical computing bits with two states (zero and one), qubits form superposition states between the two levels such that a single qubit has two states, and therefore n qubits have 2𝑛 states; thus, the powerful exponential growth for quantum computing.
The essential circuit element of superconducting qubits is the Josephson junction, which is formed by sandwiching a thin insulator layer between two superconducting electrodes. The Josephson junction, with its nonlinear inductance, makes up the artificial atom (two-level systems) that can be used as a basis for quantum computing.