THEORETICAL STUDY OF SPIN QUBIT MEASUREMENT AND COMMUNICATION
Abstract
Continued progress in the experimental research on spin qubits in Si over the past decade has pushed the system ever closer to the fault-tolerant quantum computing threshold, with single-qubit gate fidelity above 99.9% and two-qubit gate fidelity above 99.5%. Nevertheless, some challenging technical problems remain as significant road blocks, such as the search for optimal qubit design, and needs for longer coherence time, faster measurement, and long-distance communication with high fidelity. Here we propose to study theoretically two critical issues for scalable spin-based quantum computing architectures: spin measurement and spin communications. On spin measurement, we propose to perform a comprehensive evaluation including calculation of electronic spectrum and quantum capacitance in the spin blockade regime, calculation of spin relaxation and spin-flip tunneling, investigation of three-electron encoding to mitigate negative effects of small valley splitting on spin blockade, calculation of qubit response to radio frequency (RF) and microwave (MW) probe pulses, examination of the role played by the charge sensor in various spin measurement techniques and how it influences the overall measurement efficiency, fidelity, and speed, examination of measurement back action on the qubit, exploration of noise effects on the measurement fidelity and speed, and optimization of gate-based spin measurement. Altogether these studies of various aspects of spin measurement should give us a solid understanding of how to optimize spin measurement techniques. Our ultimate objective is to look for the most efficient spin measurement approach that would allow quantum error correction and fault-tolerant quantum computing. The second main direction we propose to study is on spin communication, with particular focus on schemes based on surface acoustic waves (SAW) as a carrier of either quantum information or a carrier of electron spin qubits themselves. We plan to clarify all relevant SAW modes and their quantization, electron-phonon interaction strength, electron transport fidelity, and possible decoherence effects caused by SAW. Our goals here are to establish the feasibility for SAW as a high-fidelity electron carrier, and the viability of circuit Quantum Acoustodynamics (cQAD, instead of cQED) based on SAW, both of which could be important enabling technologies for on-chip quantum information transfer in a solid state quantum computer. This abstract can be released publicly.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 22, 2022
- Source ID
- W911NF2310018
Entities
People
- Xuedong Hu
Organizations
- Army Contracting Command
- National Security Agency
- University at Buffalo