XXXVI Reunión Bienal de la Real Sociedad Española de Física

Manipulability, coherence and entanglement of acceptor qubits in Si and Ge

19 Jul 2017, 18:05

20m

Aula Química Inorgánica (Facultad de Química (USC))

Quantum Materials and Technologies (GEFES) Quantum Materials and Technologies (GEFES) II

Description

The search for electric field manipulable spin qubits has focused the attention in the recent years to high spin-orbit systems. These systems mix the spin with orbital degrees of freedom. As the orbital wavefunction is sensitive to electric fields, this mixing allows the possibility of manipulating spins entirely by electric means. The large spin-orbit coupling in the valence band of group IV semiconductors provides then with an electric field knob for hole based spin-qubit manipulation. Si and Ge are also known for their extraordinary coherence properties, making them two of the most promising candidates to host spin-qubits. In this work we consider acceptor impurities placed in these hosts. These acceptors behave as spin-3/2 particles with remarkable properties that can be tuned through both electric and magnetic fields. We find that the spin manipulation of holes bound to acceptors in engineered SiGe quantum wells depends very strongly on the electric field applied and on the heterostructure parameters. The g-factor is enhanced by the Ge content and can be tuned by shifting the hole wave-function between the heterostructure constituent layers. The lack of inversion symmetry induced both by the quantum well and the electric fields together with the g-factor tunability allows the possibility of different qubit manipulation methods such as electron spin resonance, electric dipole spin resonance and g-tensor modulation resonance. Rabi frequencies up to hundreds of MHz can be achieved with heavy-hole qubits, and of the order of GHz with light-hole qubits. We also find that by carefully choosing the parameters of the system such as the in-plane magnetic field and the applied vertical electric field it is possible to tune the entanglement and coherence properties of the system.