What is it about?

Up-to-date quantum information technologies need to distinguish individual photons. To detect single photons with microwave (10 GHz) frequency, superconducting quantum device (flux qubit) is used which must be cooled down to 10 mK temperature. Its output signal should be measured by an amplifier operating at the same temperature and consuming very low power of about 1 microwatt. We exploit an uncommon (unsaturated) regime of a High Electron Mobility Transistor (HEMT) to design such an amplifier and a whole measuring cell.

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Why is it important?

Rapid development of quantum technologies such as quantum computers, quantum communications, quantum radars, etc. require detection and counting of individual photons. While optical and infrared single-photon detectors are available even commercially, the detection of photon in microwave frequency range is much more difficult task because of small microwave photon energy (by 4-5 orders of magnitude less than that of optical ones). One of the challenge in this field is creation of a measuring system including an amplifier with extremely small heat dissipation since a dilution refrigerator has low cooling capacity at 2-10 mK temperature. Also, such an amplifier can provide low so-called back action to the quantum system which would destroy its fragile quantum states,


It was and it is a pleasure of working in this international team in a common project. As to the project, the amplifier modelling described in this paper will help us to build, test and tune a real amplifier and use it in the planned low-temperature experiment with a microwave single-photon counter measurements. I hope our paper will of interest to other research groups working in the field of low-temperature quantum measurements.

Oleg Turutanov
B. I. Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine

Read the Original

This page is a summary of: Design of deeply cooled ultra-low dissipation amplifier and measuring cell for quantum measurements with a microwave single-photon counter, Low Temperature Physics, January 2024, American Institute of Physics,
DOI: 10.1063/10.0023896.
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