The Opportunity

Lumai is redefining how the world computes. We are an ambitious, venture-backed UK startup pioneering a breakthrough AI accelerator for data centers which uses 3D optical compute. Our radical technology uses light to perform computation at orders of magnitude faster speeds and at far greater scales than ever before, all whilst consuming far less energy than traditional approaches.

Lumai is unlocking performance and efficiency gains that could transform the economics of AI and compute infrastructure and reshape how intelligence scales globally.

If you are passionate about bringing groundbreaking technology to market, and want to be part of a team pushing the boundaries of what is physically possible, Lumai is where you can make it happen.

About Lumai

Founded in 2022, Lumai is a University of Oxford spinout using optical processing to accelerate large language models (LLMs) and other transformer-based AI systems. The team combines expertise in optical computing, machine learning, and physics.

Lumai has already secured over $10 million in investment from leading deep-tech investors like Constructor Capital, IP Group, PhotonVentures and is scaling rapidly to deploy the fastest optical compute currently available globally.

The Role

We are looking for a Head of Software for Lumai's AI Application team, who will set the technical direction for how AI workloads are developed, optimised, and deployed on our accelerator hardware. This is a rare opportunity to shape a team's culture and architecture from day one — you will be both a hands-on engineer and the technical anchor for a distributed team of five (growing to ten within 18 months).

What You'll Do

• Own the end-to-end technical architecture of the AI application software stack, from SDK surface to inference runtime

• Drive engineering decisions around framework integration, model optimisation strategies, and hardware abstraction layers

• Conduct design reviews, set coding standards, and mentor engineers across inference, SDK, and tooling workstreams

• Act as the primary technical liaison between the remote European team, HQ architects, and the simulation team

• Collaborate directly with the System and HW Architects on SW/HW co-design requirements

• Lead hiring interviews for the team; contribute to technical roadmap planning with engineering leadership

• Maintain hands-on delivery — writing and reviewing production-quality code alongside the team

What We're Looking For

Must-Have

• 7+ years of software engineering experience, with at least 2 years in a tech lead or equivalent senior individual contributor role

• Deep expertise in AI/ML systems — inference pipelines, ML framework internals, model optimisation, or accelerator programming

• Strong Python and C/C++ skills; comfort working across the full stack from hardware abstraction to developer API

• Demonstrated ability to lead technically in a remote-first, distributed environment.

• Excellent cross-functional communicator, capable of working with hardware architects and product stakeholders

• Bachelor's degree or higher in Computer Science or related discipline, or equivalent experience

Strong Preference For

• Prior experience at an AI accelerator startup or in a semiconductor SW organisation

• Background in compiler design, MLIR, or custom hardware backend development

• Track record of open-source leadership or significant community contribution in ML infrastructure

Compensation & Benefits

• Highly Competitive Salary: We are not saying our salary is a blank check, but let's just say it won't be a source of your stress

• Share Option Scheme: We are all in this together! We believe in shared success while we build the Lumai of tomorrow

• L&D Allowance: Stay at the forefront of your field with a £500 annual development budget

• Holidays: Enjoy some deserved "me time" with 25 days paid holiday (plus bank holidays) per year

• Socials: Be part of an inclusive community enjoying occasional all-company off-sites, lunches and socials

Interview Process

Our process is four stages. An initial conversation with our HR team to understand what you want from the role and what we want from it. Two technical sessions with various members of our engineering team. Finally, an HR-team session covering scope, terms, and any final questions.