AVS 66th International Symposium & Exhibition
    Materials and Processes for Quantum Information, Computing and Science Focus Topic Tuesday Sessions
       Session QS+2D+EM+MN+NS-TuA

Paper QS+2D+EM+MN+NS-TuA11
2019 AVS Mid-Atlantic Student Awardee Talk: Minimizing Coulomb Oscillation Linewidth on Silicon Quantum Dots

Tuesday, October 22, 2019, 5:40 pm, Room B231-232

Session: Materials for Quantum Sciences
Presenter: Yanxue Hong, National Institute of Standards and Technology (NIST)
Authors: Y.X. Hong, National Institute of Standards and Technology (NIST)
A.N. Ramanayaka, National Institute of Standards and Technology (NIST)
M.D. Stewart, Jr., National Institute of Standards and Technology (NIST)
X.Q. Wang, National Institute of Standards and Technology (NIST)
R.V. Kashid, National Institute of Standards and Technology (NIST)
P. Namboodiri, National Institute of Standards and Technology (NIST)
R.M. Silver, National Institute of Standards and Technology (NIST)
J.M. Pomeroy, National Institute of Standards and Technology (NIST)
Correspondent: Click to Email
In quantum science research, both cryogenic temperatures and low measurement noise are required for high fidelity. For silicon quantum dot devices, an increase in either one causes broadening of Coulomb blockade peaks, which is usually referred to as a high electron temperature. Here we report on temperature-dependent (T-dependent) conductance measurements and evaluation of effective electron temperature (Teff) using an STM-patterned atom-scale silicon single-electron transistor (SET). Measurements are made in various cryogenic systems over temperatures varying from 10 mK to 25 K. The effective electron temperature is extracted by fitting the experimental data using a theoretical model. We initially find that the measured peak width has a linear dependence on the bath temperature above 1 K and saturates below 1 K. In addition, a considerable mismatch (> 2 K) between the lattice (thermometer) temperature and the carrier temperature (Teff) is observed. Therefore, the Coulomb resonance is not only thermally broadened by Teff but also broadened by other T-independent sources such as gate noise, triboelectric noise, etc. We study the origins of the saturation at low temperature regime and analyze factors inducing high Teff. We report on progress to reduce the noise and reach an effective temperature of < 300 mK. Since our silicon SETs have high charging energies and large energy level spacings, we also seek to measure the transition from classical (multilevel) regime to quantum (single-level) regime by manipulating the bath temperature.