Superconducting quantum computing team makes important progress in the development of low-temperature, low-noise amplifiers

Recently, Associate Researcher Youpeng Zhong of the Superconducting Quantum Computing Team at Shenzhen International Institute of Quantum Research (SIQA) led graduate students Zechen Guo, Shuxiang Zhao, and Jiawei Zhang to make important progress in the development of low-temperature low-noise amplifiers. The self-developed low-temperature low-noise amplifier (model: SIQA-LNA1.0) can operate at 4K ambient temperature and has the performance characteristics of low power consumption, high gain and low noise. The device has completely independent intellectual property rights, and can achieve the replacement of imported similar products.

 

Cryogenic Low Noise Amplifier (Cryo-LNA) is used to amplify low-power, high-precision RF/microwave signals in low-temperature environments and suppress environmental noise as much as possible. Cryo-LNAs are mainly used in superconducting quantum computing, silicon-based quantum computing, radio astronomy detection, and wireless communication, and are key devices for low-temperature measurement systems. The low-temperature low-noise amplifier market has long been monopolized by foreign manufacturers, with long procurement cycles and high prices, and many of them have imposed embargoes on China in recent years. In the field of superconducting quantum computing, the number of quantum bits is expected to expand to more than thousands in the near future, and a large number of low-noise amplifiers working in the 4K temperature region are needed to realize the high-fidelity reading of superconducting quantum bits.

 

The low-temperature low-noise amplifier independently developed by Shenzhen International Institute of Quantum Research can achieve high gain and extremely low noise temperature targets at 4K ambient temperature while ensuring low DC power consumption. Shenzhen International Institute of Quantum Research breaks this technical barrier and solves the problem of localization of key components in low-temperature measurement system with self-developed low-temperature low-noise amplifier, and provides technical support and product guarantee for the scale up of quantum computing.

 

Figure 1 Gain and noise temperature characterization of the amplifier under 4K ambient temperature with single-channel DC power supply. 3~8GHz band: small signal gain > 28dB, noise temperature < 6.5K, power consumption < 34mW.

 

To further verify the performance of the self-developed low-temperature low-noise amplifier (SIQA-LNA1.0), the R&D team connected the amplifier module to the superconducting quantum bit readout line. In the absence of Josephson parametric amplifier, the noise performance of the whole readout line is dominated by the low-noise amplifier.

 

In the experimental test, the resonant cavity frequency of superconducting quantum bit is around 5 GHz, and IQ scatter plot and state classification histogram are obtained with suitable readout parameters, and the measurement fidelity of |0> state and |1> state reaches 99.1% and 97.6%, respectively, which are comparable to the results of similar foreign cryogenic amplifiers. \

 

Fig. 2 (a) Scattering coefficient curve of superconducting quantum specific characteristic scattering reading

 (b)IQ scatter plot of superconducting quantum bit readout

(c)Histogram of superconducting quantum bit read state classification