Spin Qubits and Gates

Encoded Spin-qubits in Multi-quantum Dot Devices

The encoding of one spin-qubit in the state-space of more than one quantum dot is very promising since it allows qubitmanipulations via the exchange interaction with fast quantum gates. Encoded spin-qubits have provided considerableadvances on the road to spin-based quantum computing in recent years.

The encoded qubit in three singly-occupied quantum dots (the "exchange-only qubit") is the simplest system where fullsingle-qubit control is possible via exchange interactions. We describe the coherence properties of this system for whichthe first experimental studies are now being published.

Encoded qubits in a double quantum dot system are also actively studied, in particular, the question which advantagesmulti-electron quantum dots provide over single-electron encodings.

Sebastian Mehl and David P. DiVincenzo, "Noise Analysis of Qubits Implemented in Triple Dot Systems in a DaviesMaster Equation Approach," Phys. Rev. B 87, 195309 (2013).

(S. Mehl, D. DiVincenzo)