The superconducting quasicharge qubit

Understand

The non-dissipative non-linearity of a Josephson junction converts macroscopic superconducting circuits into artificial atoms, enabling some of the best controlled quantum bits (qubits) today.

• Three fundamental types of superconducting qubits are known, each reflecting a distinct behavior of quantum fluctuations in a Cooper pair condensate: single charge tunneling (charge qubit), single flux tunneling (flux qubit), and phase oscillations (phase qubit).
• Yet, the dual nature of charge and flux suggests that circuit atoms must come in pairs.
• Here we introduce the missing one, named "blochnium".