Senior Cryptography Engineer

About IonQ

IonQ, Inc. [NYSE: IONQ] is the world’s leading quantum platform and merchant supplier - delivering integrated quantum solutions across computing, networking, sensing, and security. IonQ’s newest generation of quantum computers, the IonQ Tempo, is the latest in a line of cutting‑edge systems that have been helping customers and partners including Amazon Web Services, and AstraZeneca achieve 20x performance results and accelerate innovation in drug discovery, materials science, financial modeling, logistics, cybersecurity, and defense.

In 2025, the company achieved 99.99% two‑qubit gate fidelity, setting a world record in quantum computing performance.

Headquartered in College Park, Maryland, IonQ has operations in California, Colorado, Massachusetts, Tennessee, Washington, Italy, South Korea, Sweden, Switzerland, Canada, and the United Kingdom. Our quantum computing services are available through all major cloud providers, while we also meet the needs of networking and sensing customers across land, sea, air, and space. IonQ is making quantum platforms more accessible and impactful than ever before.

This role is based onsite in Geneva, Switzerland.

We are looking for a Staff Cryptography Engineer to join our team building post-quantum cryptography (PQC) hardware acceleration for HSM and network-appliance products. You will implement the software side of modern post-quantum algorithms: reference models, optimised implementations, and the test infrastructure that proves they are correct. This is a hands‑on development role at the heart of applied cryptography, working with some of the most experienced cryptographic engineers in the field.

You will implement and maintain reference and bit‑accurate models of ML‑KEM, ML‑DSA and SLH‑DSA/LMS in C/C++/Rust and Python, develop constant‑time software implementations of cryptographic functions, and build out the known‑answer‑test and test‑vector tooling (NIST ACVP) used for verification and CAVP certification. You will contribute to the decomposition of algorithms into hardware‑friendly building blocks (Keccak, NTT and polynomial arithmetic, samplers, encode/decode), support RTL and firmware engineers with algorithm questions and debugging, and help evaluate third‑party cryptographic libraries, working under the guidance of our senior cryptography engineers.

• Implement reference models, optimised software and test‑vector infrastructure for ML‑KEM, ML‑DSA and SLH‑DSA/LMS
• Support hardware and firmware teams with algorithm expertise, debugging and certification‑oriented tooling

We are looking for a candidate with a Master’s degree (PhD a plus) in Cryptography, Mathematics, Computer Science or a related field and at least five years of experience implementing cryptographic algorithms or security‑critical software in C/C++ or Rust. You have solid understanding of modern cryptographic primitives and ideally first exposure to post‑quantum schemes (lattice‑based or hash‑based) and their underlying mathematics.

You care about correctness and write well‑tested, readable code; you understand what constant‑time implementation means and why it matters. Familiarity with NIST test‑vector formats, CAVP/ACVP or certification‑oriented development is a plus. Fluency in English is required;
French or German is an advantage.

• Hands‑on developer of cryptographic or security‑critical software with strong C/C++/Rust skills
• Solid cryptographic foundations with the ambition to build deep post‑quantum expertise

You want to grow into a world‑class applied cryptographer by working on real products with demanding correctness and security requirements, and you enjoy the discipline of code that must be…