PHYS 523 :: Physics Illinois :: University of Illinois at Urbana-Champaign

Focus area: Sub-Kelvin Techniques for Research and Quantum Industries

Introduction:

Quantum computer development is rapidly approaching the stage where scalable architectures and sensing technologies can enable practical, real-world applications. The scalability of quantum technologies—whether for computing, networking, or sensing—depends not only on advances in qubit design but also on the ability to build and maintain cryogenic platforms that are efficient, modular, and industrially deployable. As such, the cryogenic infrastructure forms a critical backbone for this emerging industry, enabling the extreme low-temperature environments to operate quantum devices such as superconducting qubits, cryogenic sensors, and ultra-stable quantum communication components. These systems typically operate at millikelvin temperatures, necessitating advanced dilution refrigerators, high-reliability cryocoolers, and robust thermal management solutions. As the quantum industry moves from laboratory-scale experiments to commercial-scale applications, a specialized workforce that can innovate and support the cryogenic infrastructure is in demand.

The MEng program at Loomis Laboratory aims to develop a workforce capable of supporting the cryogenic infrastructure needs of quantum industries, offering a multi-tiered training program that bridges physics, engineering, and practical technical skills. The curriculum includes low-temperature physics, thermodynamics, and superconductivity with applied expertise in refrigeration engineering, precision manufacturing, and materials science. The program offers hands-on experience with dilution refrigerators, vacuum systems, and cryogenic electronics, which is complemented by instruction in automation, cryogenic safety, and system integration for large-scale industrial use.

The centerpiece of our cryo-training module is a year-long project to construct a dilution refrigerator from scratch. Students will learn practical skills to design, construct, troubleshoot and solve problems needed to create a sub-Kelvin environement needed to operate quantum sensors. The MEng program also prepares individuals for diverse roles in quantum industries—ranging from cryogenic technicians to system engineers and applied scientists—while also ensuring adaptability as technologies evolve.

Activities
Tentative Schedule
References
Design resources
Microtutorials

Activities:

LN2 experience (week 3)
1. Cryogenic safety
2. Glass cryostat; measure temperature, liquid level, flow rate
3. Thermometry: thermal couple
LHe experience (week 4)
1. A dip stick in a liquid helium storage dewar
2. measures resistance vs T for SC wires, B fields, JFET, etc...
3. Thermometry: Rox, PT100, diodes, ...; sensor calibration
Machine shop (week 5, 6)
1. Mill, Lathe, Solder, Braze, ...
Building a 1K cryostat (week 7+)
1. Dipper top flange
2. Inner vacuum chamber (IVC)
3. 1K pot
Dilution refrigerator (continue in the spring semester)
A quantum sensor (sping semester)

Tentative Schedule:

week	date	topic	activities		travel (CYL)
1	8/26	Intro-radiation physics
	8/28	Intro-cryo	cloud chamber
2	9/2	project proposal; ChatGPT rules
	9/4	project proposal presention; elog
3	9/9	cryogenic: LN2	LN2: cryogenic safety; glass cryostat: measure heat load		PSI	9/9-/9/15
	9/11		T vs time; cooling block		PSI
4	9/16	cryogenic: LHe	LHe; dip stick
	9/18		LHe: dip stick & superconductivity; magnetoresistance
5	9/23	machine shop	training-1	Mill	Nara	9/19-9/29
	9/25		training-2	Lathe	Nara
6	9/30	machine shop	training-3
	10/2		training-4	solderring/brazing
7	10/7	Building the 1K cryostat	demo: Jaakko
	10/9	First Term presentation + report	2D modeling + read machine drawings : match design drawings with the parts from the machine shop
8	10/14	part 1: Dipper top flange (order brazing parts from the shop)
	10/16
9	10/21	Part 2: IVC (vacuum-tight) - dipper tubes need to be helium tight - compression fitting - Soldering - indium seals - Leak detection (use the leak detector)			FRIB	10/20-10/21
	10/23
10	10/28
	10/30
11	11/4	Part 3 : 1K pot (~ 5 weeks) - siphon tubes connection, check that the capillary is open? - soldering, leak check - thermometers - wiring + vacuum feedthroughs Measure: - temperature vs time - heat load with a heater installed - calculate various heat load (conduction from the tubes, radiation from the open ports, ...) - estimate cooling power: by measuring helium flow rate - Residual gas analysis?
	11/6
12	11/11
	11/13	Second term presentation + report
13	11/18
	11/20
14	11/25	Thanksgiving break	no meeting
	11/27	Thanksgiving break	no meeting
15	12/2
	12/4
15	12/2
	12/4
16	12/9	Final presentation & report
	12/11
17	12/16	final exam week
	12/18	final exam week

References

It is recommended that students re-familiarize themselves with the fundamentals of thermodynamics.

Additional suggested reference books:

K. Timmerhaus and T. Flynn, Cryogenic Process Engineering, Plenum (1989).
F. Pobell, Matter and Methods at Low Temperatures, Third Edition, Springer (2007).
S. W. Van Sciver, Helium Cryogenics, Second Edition, Springer (2012).
J. W. Ekin, Experimental Techniques for Low Temperature Measurements, Oxford (2006).

Design resources

Simulations

If time allows, we will introduce finite-element analysis software, that can help to simulate heat transfer to aid the heat load estimate.

COMSOL: https://www.comsol.com/heat-transfer-module

Project Management

We recommend one of the following cloud-based tools, but other choices are possible and welcome, in particular if you are already familiar!

ClickUp - https://clickup.com/
Freedcamp - https://freedcamp.com/

Design

to come.

Microtutorials

to come.