Quantifying error and leakage in an encoded Si/SiGe triple-dot qubit

Understand

Quantum computation requires qubits that satisfy often-conflicting criteria, including scalable control and long-lasting coherence.

• One approach to creating a suitable qubit is to operate in an encoded subspace of several physical qubits.
• Though such encoded qubits may be particularly susceptible to leakage out of their computational subspace, they can be insensitive to certain noise processes and can also allow logical control with a single type of entangling interaction while maintaining favorable features of the underlying physical system.
• Here we demonstrate a qubit encoded in a subsystem of three coupled electron spins confined in gated, isotopically enhanced silicon quantum dots.