TL;DR: Cat qubits use bosonic encoding in superconducting resonators to create a 'biased-noise' qubit where bit-flip errors are exponentially suppressed while phase-flip errors are tolerated. This dramatical
Cat qubits use bosonic encoding in superconducting resonators to create a 'biased-noise' qubit where bit-flip errors are exponentially suppressed while phase-flip errors are tolerated. This dramatically reduces error correction overhead: instead of ~1,000 physical qubits per logical qubit, cat qubits may need only 10-100. Alice & Bob is the leading company developing this approach.
Type
Bosonic code (biased-noise)
Overhead
10-100x fewer physical qubits per logical qubit than surface code
Threshold
Bit-flip errors exponentially suppressed by cat qubit design
Key Result
Alice & Bob demonstrated cat qubits with exponential bit-flip suppression