Networking & Interconnect Systems - Member of Technical Staff

About Us

We’re living through a Cambrian explosion of intelligence: new models and new chips, each specialised for different tasks, are arriving all at once. The result is a new era for AI, one of radical heterogeneity.

Callosum is the Intelligent Systems Company. We believe the next generation of AI won't be defined by any single model or chip, but by intelligent systems in which hardware and intelligence co-evolve. We are building the infrastructure that unifies heterogeneous compute across the full stack. This opens a new axis of scaling intelligence: a dynamic system that tailors itself to what each workload actually needs, whether that's speed, cost, precision, or whatever unit comes next.

The last era scaled on a different bet: one bigger model, more of the same chip, more data. That bet is running into structural limits. Frontier models offer extraordinary capability at unsustainable cost, one that today's monolithic infrastructure was never designed to serve.

Our founding principle is that intelligence comes from many specialised systems working together, not from any single component. We build the software orchestration layer that co-evolves models, workflows and silicon into one system, delivering inference tailored to every workload, and demonstrating orders-of-magnitude leaps in capability and cost.

Because our software spans the full stack, our engineering team works directly with heterogeneous accelerators and frontier silicon, including Cerebras, d-Matrix, Intel, NVIDIA, AMD, Normal Computing, Tenstorrent, GreatSky, and Mixx. We are not stopping at today's chips: each new generation of silicon unlocks algorithms that couldn't run before, and we intend to be first to them, every time. If we get it right, it will belong to everyone building on it - not to any single vendor.

In our latest funding round, we raised $100M, led by Atomico with participation from Plural, DCVC and the UK Sovereign AI Fund’s first investment. With this, we are building the infrastructure for the next era of intelligence.

We are engineers and scientists based in London, working across the full depth of the stack. We are curious, intellectually honest, and building what doesn't exist yet. If you thrive on uncharted territory and are energised by the scale of the challenge, we'd love to hear from you.

About the Role

Callosum believes that orders of magnitude improvements in AI systems will come through application-aware orchestration across heterogeneous hardware. As workloads become increasingly distributed, system performance depends not only on where computation happens, but on how efficiently state and data move between the hardware best suited to each part. Communication latency sets the boundary on how far that distribution can go.

This role develops the communication systems that allow heterogeneous accelerators to operate as parts of one system. You will work across protocols, memory movement, networking hardware, and the software layers above them, investigating how to make distributed execution efficient across different architectures. The work spans high-performance data transfer, emerging interconnect technologies, and communication-aware execution strategies that reduce the overhead of distributed computation.

What You'll Build

• Characterise and optimise communication paths between accelerators, tracing overhead across networking, memory, runtime, and device layers.

• Develop efficient data movement across heterogeneous hardware, exploring RDMA, programmable NICs, DPUs, and emerging networking technologies.

• Build mechanisms for transferring model state across accelerator architectures and distributed execution strategies.

• Evaluate scale-up and scale-out interconnects to inform system topology, hardware integration, and infrastructure design.

• Work with orchestration and inference teams to minimise communication overhead in distributed computational workloads.

What Sets You Apart

• Deep understanding of networking and communication systems across protocols, hardware, memory, and software layers.

• Experience with high-performance data movement, including RDMA, accelerator interconnects, programmable networking, or similar systems.

• Strong systems performance instincts, with the ability to identify bottlenecks across abstraction layers.

• Familiarity with distributed computing, memory movement, or communication patterns in high-performance workloads.

• A demonstrable tendency to question existing abstractions and design systems around the requirements of the workload.

What We Offer

• Competitive Salary, determined by skills and experience

• Equity & Ownership

• Private healthcare

• We offer Visa sponsorship and relocation benefits to hire the best in the world

• We work in person at our London office. You'll have the tools, space and setup to do your best work, and if you have specific needs, just tell us

We're committed to building an inclusive workplace where everyone feels welcome, and believe in equal opportunities for all.