2025-10-06

From September 21 to 25, 2025, the 17th European Conference on Applied Superconductivity was held in Porto, Portugal. The research team of Boreas Cryogenics presented five academic reports at the conference, reporting on a series of important research results recently achieved.
 

 

The first report, titled "Development of a high-capacity cryogen-free dilution refrigerator for the superconducting quantum computer with more than 1000 quantum bits," reviews the latest progress in developing a high-capacity, cryogen-free dilution refrigerator for cooling superconducting quantum computers with more than 1000 quantum bits, developed by a joint research team led by our company and the State Key Laboratory of Infrared Science and Technology. The joint research team possesses the complete technical chain for this type of dilution refrigerator and has achieved a minimum temperature of 6.7mK, with typical cooling capacities of 1300μW@100mK and 35μW@20mK, respectively. This report introduces the research background, summarizes the optimization strategies for key components of the dilution refrigerator, and details the operating characteristics of the entire refrigerator. The report also outlines the next phase of research: building on the important progress achieved above to achieve an even higher cooling capacity of 3600μW@100mK to meet the cooling needs of superconducting quantum computers with even more quantum bits.
 

The second report, titled "Investigation on the heat exchange system of the millikelvin dilution refrigerator with high cooling capacity for cooling superconducting quantum computers," focused on the high-efficiency heat exchanger system, a key component of the high-capacity cryogen-free dilution refrigerator described in the first report. Using a finite-difference model, the authors analyzed the impact of structural parameters of both continuous and discrete heat exchanger on refrigerator performance, determining the optimal heat exchanger parameters. In practice, by optimizing sintering pressure and temperature, we achieved a discrete heat exchanger with a specific surface area exceeding 2.8 m²/g, providing the crucial component-level support for the excellent performance of the dilution refrigerator.
 

The third report, titled "Pressure variation mechanisms in high-capacity dilution refrigerators for superconducting quantum chip cooling," focused on the pressure variation mechanisms within the high-capacity cryogen-free dilution refrigerators described in the first report. The report focused on the tube pressure losses of the dense-phase working fluid in the still within the dilution unit and the pressure losses in the continuous heat exchanger. The report summarized the basic laws governing the effects of fluid flow rate, temperature, and tube diameter on pressure variation, and derived the optimal tube diameter for refrigerators with cooling capacities ranging from 0 to 2500μW@100mK. This provided important theoretical support for the excellent performance of the aforementioned dilution refrigerators.
 

The fourth report, titled "Investigation and optimization of heat loss suppression in cryogen-free dilution refrigerators for cooling superconducting quantum processors," focused on the heat loss suppression mechanism within the high-capacity cryogen-free dilution refrigerators described in the first report. A thermodynamic model of the main heat loads in the dilution refrigerator was established, and a targeted integrated suppression strategy was proposed. The scalability of this strategy for more quantum bits was evaluated.
 

The fifth report, titled "Investigation of JT unit in a cryogen-free JT-type dilution refrigerator coupling with superconducting quantum computing chips," focused on the characteristics of the throttling unit inside the high-capacity cryogen-freedilution refrigerator described in the first report. A thermodynamic model was established to analyze the relationship between the structural parameters of the throttling unit and the refrigerator's efficiency, and successful experimental verification was conducted.
 

The above five reports are a concentrated display of the latest progress made by the joint research team of our company and the State Key Laboratory of Infrared Science and Technology in the theoretical and experimental research of high-capacity cryogen-free dilution refrigerators. During the conference, two members of the joint research team also served as session chairs for one session, respectively.