PhD Defense - James Teoh

Error Detected Operations for Bosonic Quantum In- formation Processing

Any useful quantum computer is expected to require quan- tum error correction. This means a quantum algorithm can still reliably give the correct answer despite individual qubits suffering from decoherence. But what can we do with quan- tum error detection? This is subtly different in the sense that we do not need to recover the all the quantum information once an error has been detected. It can merely suffice to re- set the faulty qubits and make a note of exactly where and when they had errors. Experimentally, this is much easier to implement, especially when our qubits are cavity qubits in a superconducting platform. I’ll show how error-detection can be used for several quantum information processing tasks such as high-fidelity quantum state transfer through very lossy links and error-detected two-qubit gates. Finally, I’ll show how error-detection can be used to realize a new erasure qubit – the dual-rail cavity qubit, which dramatical- ly eases the task of building a fully error-corrected quantum computer.