Theory of Spin Qubits (RWTH Aachen/TU Delft)


Lecture details

This lecture will be given by Professor DiVincenzo.


0) Introduction, relation to RWTH experimental program in spin qubits.

1) Qubits and spins. Choice of quantization axis and why it matters.
Rotating frame, secular approximation. Rabi oscillations, weak vs.
strong driving.

2) Spin-spin interactions. Exchange interactions (briefly).
Dipole-dipole coupling. Like and unlike spins, secular Hamiltonians.
Rare spins, singularities of dipolar coupling in this case (briefly).

3) Spin-spin interactions as noise. Noise models, Markovian noise,
Ornstein-Uhlenbeck process. Cumulant expansion for noise models
(briefly: situations where the cumulant expansion fails).

4) Bloch-Redfield theory of spin dynamics, comparison with quantum optics.
Spin-phonon coupling and spin-phonon relaxation: direct process,
two-phonon process, Orbach process.

5) Decoupling by strong Rabi driving. Static environment and
Ornstein-Uhlenbeck process. (Optional - relation to dressed states in
quantum optics)

6) Spin echo. Dynamical decoupling, toggling rotating frame, dynamical
decoupling protocols. Magnus expansion. Floquet theorem, Floquet dynamics.

7) Few-spin dynamics. Electron-nuclear systems, partial secular
approximation. ESEEM, toggling quantization axis. ESEEM for the system
of non-interacting spins, connection to the noise model (small coupling

8) Few-spin dynamics; like and unlike spins. Few-spin dynamical
decoupling. Dipolar couplings, WHH and MREV sequences.

9) Natural Orbitals: quantum dots with multiple electrons with Coulomb

10) Beyond Rotating Wave Approximation in Rabi driving.

11) Exchange only qubits -- three electrons in three dots.

12) Architectures and quantum error correction.


Solid State Physics (Bachelor level), Quantum info or quantum optics courses

Learning goals:

The students have understanding of an advanced theoretical knowledge of spin qubits. The students have the basic knowledge of qubits, spins, spin-spin interactions, theory of spin dynamics, exchange only qubits, architectures and quantum error correction, among many other spin qubit related topics. The course can complement the “Spin Qubits” course in Experimental Condensed Matter Physics study track at RWTH Aachen University.

Time Room Start/Finish
Thu 3:30pm - 6.30pm Online 15.04.2021 - 22.07.2021