研究目的
Investigating the robust and large valley splitting in a gate-defined single quantum dot hosted in molecular-beam-epitaxy-grown 28Si/SixGe1?x and its tunability by gate voltages, as well as the spin relaxation mechanisms at different magnetic fields.
研究成果
The study demonstrates a robust and large valley splitting in a gate-defined single quantum dot in 28Si/SixGe1?x, which is tunable by gate voltages. The spin relaxation time T1 exceeds 1 s at low magnetic fields and is limited by valley hotspot and phonon noise at higher fields. The findings provide a promising perspective for higher-yield spin qubit devices in Si/SixGe1?x quantum dots.
研究不足
The study is limited by the specific heterostructure and device configuration used, which may not be generalizable to all silicon-based quantum dots. The analysis of spin relaxation mechanisms at low magnetic fields requires more statistics and higher magnetic field resolution for unambiguous identification of the dominant noise source.
1：Experimental Design and Method Selection:
The study involves the characterization of a single-electron spin qubit in MBE-grown isotopically purified 28Si/SixGe1?x using pulsed gate spectroscopy and the magneto-dependence of the spin relaxation time T1. The dot-defining gate layout allows for lateral displacement of the quantum dot by changing gate voltages while keeping its size and orbital energy constant.
2：The dot-defining gate layout allows for lateral displacement of the quantum dot by changing gate voltages while keeping its size and orbital energy constant.
Sample Selection and Data Sources:
2. Sample Selection and Data Sources: The device is a double quantum dot (DQD) with an integrated nanomagnet, fabricated on an undoped 28Si quantum well with 60 ppm of residual 29Si. The heterostructure is grown by solid-source MBE.
3：List of Experimental Equipment and Materials:
The device includes a 20-nm layer of Al2O3 for insulation, depletion gates fabricated by electron beam lithography, and a Co nanomagnet for providing a local magnetic field gradient. Measurements are conducted in an Oxford Triton dilution refrigerator at a base temperature of 40 mK.
4：Experimental Procedures and Operational Workflow:
The device is tuned to the single-electron regime, and the spin relaxation time T1 is measured as a function of external magnetic field. Pulsed gate spectroscopy is used to characterize the device, and the spin relaxation rate is analyzed to determine the valley splitting.
5：Data Analysis Methods:
The spin relaxation rate is fitted with a rate equation including spin-valley and spin-orbit coupling mechanisms, combined with Johnson and phonon noise.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容
