Abstract:
Quantum devices based on semiconductors have great application potential in quantum information processing. In this talk I will introduce my PhD and Postdoc works on an acoustic-electrical-photonic hybrid system, and control/readout of quantum dot spin qubits.
First, using only regular lithography techniques on a conventional GaAs quantum well, we realize an electrically triggered single-photon source with a GHz repetition rate. In this device, a single electron is carried in the potential minimum of a surface acoustic wave (SAW) and is transported to a region of holes to form an exciton. The exciton then decays and creates a single photon. We confirm the generation of single photons using time-resolved electroluminescence measurement and Hanbury Brown-Twiss experiment.
Second, to improve control/readout of quantum dot spin qubits, we demonstrate efficient calibration of tunnel coupling crosstalk in a quadruple quantum dot array and define a set of virtual barrier gates, with which we show orthogonal control of all inter-dot tunnel couplings. We also report on cascade-based fast, high-fidelity and scalable spin readout. The cascade spin readout is based on the long-range Coulomb interaction, which maps an initial spin-to-charge conversion to a final charge transition near a charge sensor. In the end of the talk I will briefly show our work on quantum simulation of Heisenberg model using electron spins.