Abstract
The feasibility of high-fidelity single-qubit operations on a hole spin in a quantum dot molecule by electric g tensor control is demonstrated. Apart from a constant external magnetic field the proposed scheme allows for an exclusively electric control of the hole spin. Realistic electric gate bias profiles are identified for various qubit operations using process-tomography-based optimal control. They are shown to be remarkably robust against decoherence and dissipation arising from the interaction of the hole with host-lattice nuclear spins and phonons, with a fidelity loss of ≈1% for gate operation times of≈10 ns. Spin-echo experiments for the hole spin are modeled to explore dephasing mechanisms and the role of pulse-timing imperfections in the gate fidelity loss is discussed.
Highlights
We propose and study feasibility of all-electric control of a qubit realization based on the hole spin in a quantum dot molecule
This system offers two main advantages over electron-spin-based realizations: the use of hole spins increases the dephasing time associated with the interaction with nuclear spins by about an order of magnitude and allows for an efficient g tensor control, thereby facilitating essentially all-electric control of the qubit
Spin-based quantum bit realizations in semiconductor quantum dots have gained wide interest in the quantum computing community due to their potential regarding scalability and their long relaxation times. Both theoretical and experimental, has focused on electron spin qubits, which have spin relaxation times ranging from several milliseconds[1] up to seconds.[2]
Summary
We propose and study feasibility of all-electric control of a qubit realization based on the hole spin in a quantum dot molecule. This system offers two main advantages over electron-spin-based realizations: the use of hole spins increases the dephasing time associated with the interaction with nuclear spins by about an order of magnitude and allows for an efficient g tensor control, thereby facilitating essentially all-electric control of the qubit. The model for the interaction of the nuclear spins with the hole is detailed in Appendix A and B
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