A study on quantum computation using electron spins of semiconductor quantum dots

Philosophisch-Naturwissenschaftlichen Fakultät

Yin‐Zhong Wu

Based on electron spin in semiconductor quantum dot,we implement a quantum control-NOT gate without using spin-spin interaction.The electron spin state is selected as qubit state,and only the single qubit operation is used in our scheme.

Tuukka Hiltunen

Daniel Loss

Haifeng Qiao, Yadav P. Kandel, Saeed Fallahi +4 more

Because of their long coherence times and potential for scalability, semiconductor quantum-dot spin qubits hold great promise for quantum information processing. However, maintaining high connectivity between quantum-dot spin qubits, which favor linear arrays with nearest neighbor coupling, presents a challenge for large-scale quantum computing. In this work, we present evidence for long-distance spin-chain-mediated superexchange coupling between electron spin qubits in semiconductor quantum dots. We weakly couple two electron spins to the ends of a two-site spin chain. Depending on the spin state of the chain, we observe oscillations between the distant end spins. We resolve the dynamics of both the end spins and the chain itself, and our measurements agree with simulations. Superexchange is a promising technique to create long-distance coupling between quantum-dot spin qubits.

Zhan Su, Tu, Tao, Cao, Gang +2 more

We propose an approach to reconstruct two-electron spin qubit states in semiconductor quantum dots by employing tomographic techniques. This procedure exploits the combination of fast gate operations on electron spins trapped in dots and dynamical nuclear polarization of the underlying Ga and As nuclei. The presented method can be an important tool in solid state quantum computation for complete characterization of qubit states and theirs correlations.