“Coherent control of field gradient induced quantum dot spin qubits”

Dr. Dohun Kim
Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University

Nov. 20 (Fri.), 04:00 PM
Online seminar
https://kaist.zoom.us/j/82243139535
회의 ID: 822 4313 9535
암호: 151742

Abstract:
The electron spin degree of freedom in solids form natural basis for constructing quantum two level systems, or qubits. The electron spin qubit offers a route for fast manipulation of spins using magnetic resonance or field gradient induced electric control, but generally suffers from dephasing due to strong coupling to the environment, especially nuclear spin bath, where decoherence dynamics is often non-Markovian and quasi-static. This talk will review experimental progress of fast GaAs based spin qubits and efforts to mitigate or even control the environment nuclear spin bath using hyperfine interaction. Starting from discussing general introduction to quantum transport measurements in quantum dots, circuit design, and need for high-throughput measurement methods for developing highly coherent and scalable qubit platform, I will focus on implementations of advanced quantum measurement and control protocols of singlet-triplet qubits including high fidelity singlet-shot measurements, Bayesian estimation-based adoptive control, and sequential Monte-Carlo method. In particular, we show that clever quantum control using FPGA-based hardware programming enables real time Hamiltonian parameter estimation actively suppressing quasi-static noise.