Cryostat Bluefors XLD400

A dilution refrigerator reaching sub-10mK to be used for state-of-the-art superconducting qubit characterization in the characterization team at NQCP. The systems will consist of several wire trees with drive, readout and flux lines. It should have a proven track record for such an experiment within the superconducting community. The system should allow for upgrades with additional lines.The acquisition of a Bluefors XLD450sl dilution refrigerator is necessary to maintain compatibility with the existing fleet of Bluefors refrigerators deployed within NQCP and Quantum Foundry. The scientific programme requires direct transfer as well as comparison of side-loading wiretrees and quantum processor assemblies between refrigerators to enable reproducible benchmarking and optimization of superconducting quantum processors across multiple facilities. Compatibility with existing wiretree infrastructure is a mandatory requirement and cannot be achieved without substantial redesign and interruption of ongoing research activities. Furthermore, maintaining a homogeneous refrigerator platform ensures identical measurement environments, including cryogenic architecture, pulse-tube configuration, thermalization scheme, and attenuation chain, which is essential for scientifically valid comparisons between quantum processor devices. Five Bluefors refrigerators are already integrated into the NQCP and Quantum Foundry ecosystem. The use of a common platform minimizes operational risk, reduces maintenance costs, leverages existing technical expertise, and ensures continuity of ongoing experimental programmes.