Fault-tolerant quantum error detection with a Kerr-cat qubit

Francesco Adinolfi
Paul Scherrer Institut, Switzerland

In order to explore the potential benefits of quantum computing, we first need to be able to encode quantum information in a robust manner. Quantum error correction achieves this by encoding quantum information redundantly in a logical qubit such that errors can be detected and corrected.

In an error correction cycle, the logical qubit interacts with an auxiliary qubit (ancilla) such that an error syndrome is mapped onto the latter which can then be measured. During this process, it is crucial to avoid propagating non-correctable errors from the ancilla to the logical qubit. A promising avenue to tackle this challenge is to use strongly noise-biased qubits as ancillas.

Noise-biased qubits feature one error channel that is strongly suppressed with respect to the other. This property makes it possible to engineer a unitary interaction between the ancilla and the logical qubit that commutes with the unsuppressed ancilla error channel, rendering the logical qubit nearly immune to ancilla errors.

In this project, we will employ the Kerr-cat qubit, which has been recently demonstrated in the framework of superconducting circuits, for this task. I will present the main experimental results for this novel qubit and discuss the benefits of using it as an ancilla qubit for quantum error correction.