Vibration Decoupling for Dilution Refrigerators

This invention mechanically decouples the sample holder from the surrounding cryostat, making it ideally suited for quantum computing and particularly vibration sensitive measurement applications. Unlike previous solutions, it combines virtually indefinite continuous operation time at constant low temperature with minimal mechanical noise and easy handling – and can be retrofitted in most commercially available cryostats. Due to the cumbersome handling and need for a continuous supply of expensive coolant in
conventional wet cryostats, dry cryostats, with pulse-tube coolers doing the pre-cooling at the push of a button, have grown ever more popular. However, these come at the cost of additional vibrations within the cryostat itself. Thus, especially vibration-sensitive applications require pausing the pulse-tube cooler and relying on passive insulation. This is of course not possible for indefinite periods of time.

In this patent-pending system, the sample holder is hanging freely inside the cryostat,
effectively decoupling the two. The connection to the external mount consists of multiple stages of mechanically damping and thermally insulating components. In order to reach target temperature <10 mK, the support incorporates additional radiation shielding as well as mechanically flexible thermal bridges to select stages of the cryostat. A lab-scale prototype has been in use by the inventors for more than a year supporting several different use cases. Resulting mechanical noise is at least as low as for wet cryostats.

• Possible upgrade for commercial cryostats with minimal impact on the size of the available sample volume
• In dry cryostats, almost no vibrations are transferred to the sample even when the pulse-tube cooler is on
• Multi-stage thermal insulation and mechanical damping ensure minimal interference from external support
• Laboratory-scale tested prototype available

TRL 4