Lab Experience

Transport, scanning probe microscopy, instrumentation and troubleshooting; database management; data visualization

Leiden CF900 Dilution Refrigerator

  • Superuser experience: May 2016 - Sep. 2019.
  • Experienced on operation, maintenance, troubleshooting such from the cryostat, gas handling system, pumps, pulsed tube compressor, superconducting vector magnet and power supply, thermometers.
  • The fridge reached 5.2 mK when no probe was loaded.
  • We replaced magnet leads, replaced membrane of mixture compressor, replaced the mixture pump, added a third cold trap, removed the bypass in the helium pulsed tube compressor, removed the precool circuits due to the leak, changed pulse tube flexlines, recharged small amount of helium-3, replaced plunger in the valve, replaced the fiberglass rods of the probe, made clamp reinforcement to the probe, integrated to the lab database I setup, replaced the fans in the power supply of the vector magnet, cooling power test, single-shot, etc.
  • Trained 4 users.

 

QD PPMS and VSM

  • Superuser experience: May 2015 - May 2019.
  • Was in charge of cryogens transfers, regular maintenance, troubleshoot. We warm up PPMS October 2015 - November 2015 to clear the blocked impedance and cool back down. It has been running very well since then.
  • Did about 300 helium transfers.
  • Trained 10 users.

 

Asylum Research MFP-3D

  • Superuser experience: April 2016 - April 2018.
  • Bulilt a confocal microscope onto MFP-3D, with single-photon counting capability (avalanche photodiode). The setup was capable of doing simultaneous imaging of the photoluminescence with the existing AFM scanning modes.
  • 920 hours of usage.
  • Trained 7 users.

 

MilliKelvin Scanning Probe Microscope (SPM)

  • Superuser experience: August 2015 - Sep. 2019.
  • Instrumentation: Extended the capability of electron waveguide writing with conductive AFM lithography to this SPM. Modified the source code to adjust the engage behavior/speed, etc, of the SPM during lithography.

 

Data visualization and Programming

  • Python: data analysis and multi-index manipulation (Numpy, Scipy, Pandas, xarray), high-precision math (mpmath), visualization (matplotlib, plot.ly, BlenderPy), website (Django), instrument automation (pyvisa, nidaqmx-python, pythonnet, pywinauto), probabilistic modeling (pyMC3), machine learning (scikit-learn), deep learning (Keras, tensorfow 2.0), computer vision (openCV), quantum physics and quantum optics (qutip, strawberry field).
  • LabVIEW (NI-DAQmx, JKI state machine, etc).
  • Mathematica.
  • bash, zsh.
  • Google Script, JavaScript, HTML/CSS (this website).
  • My GitHub: https://github.com/yypai
  • Medium: https://medium.com/@nosaash

 

Database setup and management

  • I setup and manage (June 2014 - Jan. 2020) a lab-wide database in our research group. It collects the stats for various instruments of the lab as time series, from the flow rate, dump pressure, of the dliution refridgerators, the gate voltages applied to device under test, to the humidity and temperature of the lab.
  • It has now 659 time-series and size about 400 GB.
  • The database has become an indispensable part of our lab and successfully helped us troubleshoot our lab instruments numerous times.