Homemade-HEMT-based transimpedance amplifier for high-resolution shot-noise measurements.

Area of Science:

• Condensed Matter Physics
• Quantum Electronics
• Semiconductor Device Physics

Background:

• Cross-correlation measurements are essential for characterizing quantum systems.
• Existing amplifiers often suffer from noise and crosstalk, limiting measurement resolution.
• High-electron-mobility transistors (HEMTs) offer promising low-noise characteristics.

Purpose of the Study:

• To develop a cryogenic transimpedance amplifier (TA) optimized for cross-correlation current-noise measurements.
• To achieve high resolution in noise measurements by minimizing amplifier noise and sample crosstalk.
• To validate the TA's performance in a relevant quantum system.

Main Methods:

• Fabrication of homemade high-electron-mobility transistors (HEMTs) in an AlGaAs/GaAs heterostructure.
• Integration of HEMTs into a cryogenic transimpedance amplifier (TA) circuit.
• Experimental setup utilizing the TA for shot noise measurements at a quantum point contact (QPC) within a quantum Hall system.

Main Results:

• The developed cryogenic TA exhibits low input-referred noise and a wide frequency band.
• The TA's low input impedance effectively suppresses crosstalk between sample currents.
• Demonstrated high resolution in current-noise measurements via shot noise detection at a QPC.

Conclusions:

• The cryogenic transimpedance amplifier (TA) is highly suitable for advanced cross-correlation current-noise measurements.
• The TA's performance, characterized by low noise and suppressed crosstalk, significantly enhances measurement resolution.
• The TA provides a valuable tool for investigating quantum phenomena in systems like quantum Hall effect devices.