A wideband cryogenic microwave low-noise amplifier

Area of Science:

• Cryogenic Engineering
• Solid-State Electronics
• Quantum Computing Hardware

Background:

• Cryogenic environments are crucial for sensitive measurements, demanding low-noise amplification.
• High-electron-mobility transistors (HEMTs) offer potential for low-noise amplification at low temperatures.
• Existing amplifiers may not meet the stringent requirements for advanced cryogenic applications.

Purpose of the Study:

• To design and characterize a broadband, low-noise, four-stage HEMT amplifier for cryogenic applications.
• To evaluate the amplifier's performance at a 3.8 K temperature stage within a cryogen-free dilution refrigerator.
• To demonstrate the amplifier's utility in characterizing superconducting quantum bits (qubits).

Main Methods:

• Designed a four-stage HEMT amplifier circuit.
• Characterized the amplifier within a cryogen-free dilution refrigerator at 3.8 K.
• Measured power dissipation, gain across a frequency range, and equivalent noise temperature.
• Utilized the amplifier to characterize a superconducting X-mon qubit coupled to a coplanar waveguide resonator.

Main Results:

• Achieved power dissipation below 20 mW.
• Obtained a gain exceeding 30 dB in the 6 to 12 GHz frequency range.
• Demonstrated an equivalent noise temperature below 6 K across the specified frequency range.
• Successfully applied the amplifier for superconducting qubit characterization.

Conclusions:

• The developed broadband low-noise amplifier meets critical performance metrics for cryogenic measurements.
• The amplifier's low noise and high gain make it suitable for various cryogenic microwave applications.
• The successful characterization of a superconducting qubit validates the amplifier's practical utility in quantum information science.