Abstract The Sub-milikelvin Experimental Station (C1 station) in Synergetic Extreme Condition User Facility consists of a dilution refrigerator for millikelvin-temperature experiments and a nuclear adiabatic demagnetization refrigerator (NADR) for sub-millikelvin temperature experiments. In the NADR, we have achieved temperatures as low as 0.32 mK while maintaining the capability to apply a 16 T magnetic field to the sample. The system can sustain temperatures below 1 mK for more than ten days. Under these conditions—ultra-low temperature, high magnetic field, and ultra-low noise—the Sub-milikelvin Experimental Station has enabled users to conduct a series of pioneering experimental studies.
Abstract The Sub-milikelvin Experimental Station (C1 station) in Synergetic Extreme Condition User Facility consists of a dilution refrigerator for millikelvin-temperature experiments and a nuclear adiabatic demagnetization refrigerator (NADR) for sub-millikelvin temperature experiments. In the NADR, we have achieved temperatures as low as 0.32 mK while maintaining the capability to apply a 16 T magnetic field to the sample. The system can sustain temperatures below 1 mK for more than ten days. Under these conditions—ultra-low temperature, high magnetic field, and ultra-low noise—the Sub-milikelvin Experimental Station has enabled users to conduct a series of pioneering experimental studies.
Accessibility to the microkelvin temperature regime is important for quantum technology research. Cryogen-free dilution refrigerators opened up the millikelvin temperature range, but the perception is that ultralow temperatures are difficult to reach and require specialist infrastructure. The authors report the design of a microkelvin platform based on a nuclear-demagnetization stage, engineered and optimized for operation on a cryogen-free dilution refrigerator. The study demonstrates temperatures as low as 395 $\ensuremath{\mu}$K, and a protocol that enables experiments operated below 1 mK for 95% of the time, providing an efficient cryogen-free microkelvin environment for a wide range of applications.
The superconducting quantum computer with strong data storage capability and fast execution speed has attracted a lot of attention in recent years and is finding practical applications in fields such as finance, military, biomedicine, and artificial intelligence. To suppress the thermal noise and to achieve high coherence, the quantum chips require millikelvin temperature, which poses a significant challenge for the suitable cryogenic system. The dilution refrigerator (DR) with ultra-low vibration and electromagnetic interference becomes an appropriate candidate for this purpose. To achieve the aimed millikelvin temperature, a cryogen-free DR composed of a Gifford-McMahon type pulse tube refrigerator (GM-type PTR), Joule-Thompson refrigerator (JTR), and dilution unit is investigated. This article presents the structural design of the DR and the coupling system with superconducting quantum chips. The cooling performance of the designed DR is estimated based on the developed cryogenic system. The minimum deduced temperature of 0.76 K in the still is achieved and the next steps to obtain the final temperature of 5 mK are underway.
Abstract We report recent progress toward the realization of a sub-mK, low-vibration environment at the bottom stage of a dry dilution refrigerator for use in mechanical tests of quantum mechanics. Using adiabatic nuclear demagnetization, we have cooled a silicon cantilever force sensor to T≈1 T ≈ 1 mK. The temperature of the tip holder of the cantilever chip was determined via a primary magnetic flux noise thermometer. The quality factor of the cantilever continues to increase with decreasing temperature, reaching Q≈4⋅104 Q ≈ 4 · 10 4 at 2 mK. To demonstrate that the vibration isolation is not compromised, we report the detection of the thermal motion of the cantilever down to T≈20 T ≈ 20 mK, only limited by the coupling to the SQUID readout circuit. We discuss feasible improvements that will allow us to probe unexplored regions of the parameter space of continuous spontaneous localization models.
Mostafa, Md Asif Installation and Characterization of a Superconducting Quantum Interference Device (SQUID) in an Adiabatic Demagnetization Refrigerator (ADR) Master’s thesis Department of Physics, University of Jyväskylä, 2026. This thesis presents the installation and characterization of a two-stage dc superconducting quantum interference device (SQUID) system in an adiabatic demagnetization refrigerator (ADR). The work combines the physical principles of superconductivity, Josephson junctions, SQUID operation, flux-locked-loop readout, and ADR cooling with practical low-temperature implementation. The SQUID system was integrated into the ADR through a cryogenic signal chain including electrical interface mapping, cryogenic wiring, filtering, thermal anchoring, and room-temperature readout electronics. The experimental characterization included voltage–flux modulation measurements, transfer-function and mutual-inductance calculations, gain calibration, and noise analysis. The measured two-stage combined transfer function was close to the value in the datasheet, confirming that the installed system reached the expected operating regime. The feedback and input-coupling parameters were extracted and compared with datasheet values, while the gain calibration provided the transimpedance needed to convert output-voltage noise into equivalent input- current noise. The initial commissioning-stage measurements showed a white input-current noise level of a few picoamperes per square root hertz and a feedback-resistance- dependent bandwidth. Later optimized measurements demonstrated that the ADR- based SQUID platform could reach a lower noise floor and larger bandwidth after reducing setup-related noise sources. These results show that the installed platform can support low-noise SQUID operation and provides a useful basis for future cryogenic detector and superconducting-device measurements. Keywords: SQUID, Adiabatic Demagnetization Refrigerator (ADR), Josephson junction, flux-locked loop, two-stage SQUID, mutual inductance, cryogenic readout, low-temperature physics.
The goal of my thesis was to construct a general purpose cryostat, capable of measuring multiple devices at 100mK. This included modifying an existing SHASTA model 106 Adiabatic Demagnetization Refrigerator (ADR) by adding a new physical support structure to allow for more weight to be added to the cryostat’s testing stages, as well as custom pieces of electronics, such as a room temperature programmable current source. This allowed for computer programs to be written so we could automate the data acquisition process. \nWe successfully measured multiple superconducting quantum interference devices (SQUIDs), with the goal of proving that our custom electronics were able to control and record the output of the SQUID. This included measuring the biasing conditions of the SQUID with \nthe automated current sources, as well as measuring the noise temperature of a SQUID down to 300mK. Furthermore, we measured the thermal conductivity of our new sup- port structure for the cryostat and were able to prove that the material used was new \nand novel approach for high strength, low thermal conductivity in cryogenic research. We also investigated a new technique in permanently modifying the operational frequency of a SQUID, and were able to show that this new method of laser ablating the input coil could successfully shift the frequency. While the focus of cryogenic testing was on SQUIDs the cryostat itself was designed in such a way such that many types of low temperature devices could be tested within the system.
A cryogen-free cryostat was set up in order to perform measurements at ultra low temperatures. The setup involved the removal of an adiabatic demagnetization refrigerator (ADR) and replacing it with a dilution refrigerator system. The modified cryostat is able to provide continuous cooling power, enabling greater flexibility over the ADR in the type of low temperature experiments that can be performed. Condensation stages, main flow impedance and radiation baffles were designed, constructed and installed into the cryostat. Several general cryostat design considerations are also discussed. Condensation of the incoming 3He - 4He mixture utilizes only the cooling power of the two-stage pulse tube refrigerator. For a circulation rate of 120 μmols/sec, the base temperature of the cryostat is 70 mK with a cooling power of 33 μW of heat at 100 mK. \nWith this cryostat, a measurement system is developed for studying superconducting microwave resonators. Residual losses in these devices continue to impede their performance in applications such as ultra sensitive detectors and quantum computing. A microwave circuit consisting of coaxial cables, attenuators and amplifiers was installed on the cryostat to measure losses in these devices. Data analysis and fitting procedures were written in Python programming language to extract key resonator properties. Characterizing and understanding loss mechanisms for these devices will lead to improved materials and fabrication methods. This will ultimately result in losses that approach the fundamental limit set by the Mattis-Bardeen theory.