Quantum control of a cat-qubit with bit-flip times exceeding ten seconds

Quantum bits (qubits) that are inherently protected against certain types of errors are promising candidates for scalable quantum computing. An outstanding challenge is to control such a qubit without breaking its protection. A recent qubit - the cat-qubit - is encoded in the manifold of metastable states of a quantum dynamical system, thereby acquiring continuous and autonomous protection against bit-flips. In this superconducting circuit experiment, we implement a cat-qubit with bit-flip times exceeding ten seconds. This is a four order of magnitude improvement over previous cat-qubit implementations. We prepare and image quantum superposition states, and measure phase-flip times above 490 nanoseconds. Most importantly, we control the phase of these quantum superpositions without breaking bit-flip protection. This work demonstrates quantum operations that preserve bit-flip times above ten seconds, a necessary step to scale these dynamical qubits into fully protected hardware-efficient architectures.

Preprint : arxiv:2307.06617