Cryogenics on Joe Wiedemann

PXS Microwave Electronics

Sun, 15 Feb 2026 00:00:00 +0000

PXS Electronics Work

As we develop new state-of-the-art amplifier technology for sub-GHz bands, we have needed to develop supporting infrastructure for the auxillary components that make up the rest of our read out chain. Two of the standout infrastructure pieces has been designing room-temperature analog circuitry that controls a cryogenic multi-pole switch, and designing superconducting lumped-element diplexers. This work is complimentary to the effort to develop high quality coaxial cable - see more on that work in PXS Coax Development.

PXS Cryogenic Coax Development

Tue, 20 Jan 2026 00:00:00 +0000

Coaxial Cable and PXS Readout

High-quality cryogenic coaxial cable is critical to sensitive microwave exferiments. While the expanding market in support of quantum computing has introduced numerous commericial solutions for bulk and/or high-density cable, these offerings remain expensive and require a-priori knowledge of the system design. By developing laboratory methods to fabricate our own cable I was able to reduce lead times and cost, achieve greater freedom in our RF system design, and provide bespoke-level focus that has resulted in leading systematic performance.

Passive pyrolytic graphite heat switch for sub-Kelvin coolers

Fri, 18 Apr 2025 00:00:00 +0000

Motivation

Cryogenic systems have the contradictory requirement of needing high thermal conductivity during the bulk cooldown period, and maximized thermal isolation at the base temperature operation. Heat switches provide a mechanism to change the thermal conductivity between two stages. A typical design is to use a gas-gap heat switch which uses a heater to expel Helium gas as a conduction mechanism between the two sides of the switch. These active switches can be costly and require additional DC wiring instrumentation in the cryostat. For large thermal masses in bulk cooldown, this can be an excessive effort to accelerate the cooldown process. However, pyrolytic graphite sheet demonstrates passive heat switch capabilities as the phonons freeze out and create minimal loading at base temperature. By analyzing the cryogenic performance of a custom-designed graphite heat switch, we were able to implement heat switches that sped up our bulk cooldown from ~4 days to ~2 days for less than 10% the cost of a gas-gap heat switch and without additional wiring instrumentation.

PXS Cryogenics

Wed, 10 Apr 2024 00:00:00 +0000

PXS Cryogenic Requirements

The Princeton Axion Search is a cavity Haloscope-style experiment, which requires cryogenic solutions to cool a superconducting magnet storing 6 mega-joules of energy, while simultaneously bringing the cavity detector and readout electronics to 40 milli-Kelvin (40 thousandths of a degree above absolute zero). Similar systems that cool large magnets, like MRI machiens, cool the magnet down by containing the system in a liquid Helium bath. These liquid helium baths are expensive and require sophisticated pressure vessels to handle the forces in case a magnet disruption rapidly boils the liquid Helium. As an academic research group, these requirements for liquid Helium designs would make the experiment prohibitively expensive. We are designing the experiment to be cooled entirely through conduction paths to pulse tube cryocoolers.