Principal Engineer, Cryogenic Refrigeration Systems

Snowcap is building a superconducting digital computer that operates at cryogenic temperature. The refrigeration system is not a facility accessory; it is core product infrastructure. It determines system uptime, test throughput, deployment cost, serviceability, vibration environment, cooldown time, and ultimately whether superconducting compute can operate outside a physics lab.

This role owns the refrigeration architecture behind that system. You will lead the design, specification, integration, and validation of Snowcap’s cryogenic cooling stack, with particular emphasis on the compressor, helium circuit, cold head, heat rejection, and mechanical interfaces to the compute payload.

We are looking for a mechanical engineering leader with deep cryogenic refrigeration experience. The right person has worked close to real hardware: compressors, pulse tube or Gifford-McMahon cryocoolers, helium plumbing, vacuum interfaces, heat exchangers, vibration isolation, sensors, valves, leak checking, cooldown testing, and field reliability. This is a hands-on technical leadership role for someone who can set architecture, challenge vendor assumptions, debug hardware, and establish the standards that future Snowcap cryogenic systems will follow.

In twelve months, the right person in this role will have defined and validated a refrigeration architecture that supports Snowcap’s superconducting compute roadmap, with clear paths to reliability, manufacturability, supplier qualification, serviceability, and customer deployment.

Own Snowcap’s cryogenic refrigeration architecture end-to-end, from compressor package and helium circuit through cold head, thermal interfaces, heat rejection, controls, instrumentation, and service envelope.

Define system-level requirements for cooling power, base temperature, cooldown time, pressure, flow, vibration, acoustic noise, power consumption, heat rejection, uptime, redundancy, maintenance, and safety.

Lead compressor-level trade studies across helium compressor technologies, oil management, pressure ratios, water cooling, duty cycle, efficiency, service intervals, vibration, acoustics, reliability, and integration constraints.

Specify, evaluate, and qualify cryocoolers, compressors, cold heads, vacuum components, gas handling hardware, chillers, sensors, valves, lines, fittings, manifolds, and related refrigeration components.

Build the analytical and empirical models that govern Snowcap’s refrigeration decisions: thermal budgets, cooldown curves, parasitic heat loads, pressure drop, flow distribution, compressor operating envelopes, and failure modes.

Design and review mechanical subsystems including gas lines, manifolds, heat exchangers, cold plates, thermal straps, mounting hardware, vibration isolation, vacuum interfaces, water-cooling interfaces, and serviceable assemblies.

Develop Snowcap’s cryogenic refrigeration test strategy, including cooldown testing, heat-load mapping, vibration characterization, compressor performance testing, leak testing, reliability growth, and failure analysis.

Work directly with superconducting hardware, packaging, test, manufacturing, facilities, and controls teams to define clean thermal and mechanical interfaces between the compute system and the refrigeration plant.

Drive vendor selection and supplier qualification for key cryogenic refrigeration components, including technical specification, acceptance criteria, incoming inspection, and long-term reliability expectations.

Translate lab cryogenic systems into product-grade infrastructure: documented, maintainable, manufacturable, serviceable, and capable of sustained operation in Snowcap facilities and future customer environments.

Establish the engineering standards, design rules, safety practices, test procedures, and documentation that define how Snowcap builds cryogenic refrigeration systems.

Mentor mechanical, thermal, and systems engineers as Snowcap grows the cryogenic infrastructure function.

10+ years of experience designing, building, testing, or sustaining cryogenic refrigeration, thermal-fluid, compressor-based, vacuum, or high-reliability mechanical systems.

Deep mechanical engineering fundamentals in thermodynamics, heat transfer, fluid mechanics, pressure systems, mechanical design, vibration, reliability, and instrumentation.

Direct experience with helium refrigeration, cryocoolers, pulse tube systems, Gifford-McMahon systems, Stirling systems, superconducting magnet cooling, MRI cryogenics, quantum cryogenic infrastructure, semiconductor cryogenic tools, or comparable low-temperature systems.

Hands-on experience with compressor-level design or integration: helium compressors, oil-free or oil-managed compression systems, water-cooled compressor packages, pressure and flow control, heat rejection, duty cycle, service intervals, and failure modes.

Ability to design and debug real thermal-fluid hardware using pressure, temperature, flow, vibration, acoustic, power, and leak-rate data.

Strong mechanical design capability, including CAD, drawings, GD&T, materials selection, sealing, vacuum-compatible design, weldments, brazed or welded assemblies, and serviceable mechanical packaging.

Experience working with external suppliers on specification, qualification, acceptance testing, cost, reliability, and manufacturability.

Demonstrated ability to make architecture-level decisions under incomplete information, then validate those decisions through analysis, testing, and iteration.

BS, MS, or PhD in Mechanical Engineering, Aerospace Engineering, Cryogenic Engineering, Thermal Sciences, or equivalent demonstrated depth through industry work.

A track record of ownership: systems that operated in the real world, had your name on them, and required you to answer when something failed.

Snowcap is a small, technically elite team building hardware that has not existed at commercial scale. The cryogenic refrigeration system you will lead is not a mature subsystem with a playbook to inherit. It must be defined from first principles, validated against real hardware, and made practical enough to support Snowcap’s path to commercial superconducting compute.

We are a flat, matrixed organization. You will work directly with superconducting device leads, packaging engineers, test engineers, facilities owners, manufacturing leaders, and executive leadership. There are no layers between you and the problem. If the compressor architecture is wrong, if the cooldown time is too long, if vibration couples into the payload, if the service interval is unacceptable, or if the thermal budget does not close, this role owns the path to resolution.

This role is on-site because the work is physical. The hardware is real, the interfaces are unforgiving, and the test data matters. If you want a narrow analysis role, this is not the right fit. If you want to own the refrigeration system that makes superconducting compute deployable, this is the right seat.

Snowcap Compute is building the world's first commercial superconducting digital computer. Our chips operate at 4.5 Kelvin on Josephson junction-based PCL logic, consuming a fraction of the power of any CMOS system. We are not improving the existing paradigm — we are replacing it.

We are a technically elite, small team at the intersection of quantum physics, cryogenic engineering, and advanced semiconductor manufacturing. Every person on this team has a direct line of sight to the product. The work you do here will be visible, consequential, and unprecedented.

Full medical, dental, and vision · 401(k) · Relocation assistance available for candidates outside the area.

Base salary range is shown in USD and reflects the Jacksonville Metro labor market for this role, calibrated against NASA federal pay scale (Palm Bay locality) and comparable FL semiconductor / defense private-sector roles. Actual offer depends on experience, skills, and seniority, and is exclusive of equity, bonus, and benefits. Florida has no state income tax; relocating candidates should factor that into side-by-side comparisons with high-tax-state offers.

Snowcap is an equal opportunity employer. We do not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or any other protected characteristic.

Compensation in line with senior roles in this area.