zerothird GmbH is seeking a highly skilled Quantum Optics Engineer to join our innovative team in Vienna, focusing on the development, characterization, and operation of entanglement-based Quantum Key Distribution (eQKD) systems. This role is centered on, but not limited to, hands-on experimental work in the lab, contributing to the design, optimization, and stabilization of optical and opto-electronic subsystems. The position also interfaces closely with software and systems engineers to ensure robust, scalable, and performant quantum communication systems. We particularly welcome applications from women to further increase diversity among us.

• Experimental Quantum Optics Development: Design, build, align, and operate optical setups for polarization-entangled photon sources and entanglement-based QKD systems, including free-space and fiber-based implementations.
• System Characterization & Optimization: Perform detailed measurements of source brightness, entanglement quality, loss, timing, and stability; analyze results and iteratively improve system performance and robustness.
• Laboratory Operations: Take ownership of laboratory experiments, including optical alignment, calibration of detectors and electronics, troubleshooting of experimental issues, and documentation of setups and procedures.
• Automation & Control: Develop and maintain experiment control, data acquisition, and analysis software (e.g. for measurements, calibration routines, and long-term stability tests).
• Cross-Disciplinary Collaboration: Work closely with software, electronics, and systems engineers to integrate optical subsystems into full QKD nodes and network deployments.
• Technology Evolution: Contribute to the exploration and prototyping of next-generation components and concepts, including improvements to entangled photon sources and optical subsystems.

• Educational Background: Master’s degree or PhD in Physics, Applied Physics, Quantum Optics, Photonics, or a closely related field.
• Experimental Experience: Strong hands-on laboratory experience in quantum optics or photonics, including optical alignment, use of lasers, single-photon detectors, fiber optics, and standard optical instrumentation.
• Quantum Communication Knowledge: Familiarity with entanglement-based QKD concepts, polarization optics, and quantum state characterization is highly desirable.
• Programming Skills: Practical experience writing code for experiment control, data acquisition, or data analysis (e.g. Mathematica, Python, C/C++, or similar).
• Specialized Knowledge (Highly Regarded):
  • Experience with nonlinear optics (e.g. SPDC sources, crystal-based photon-pair generation)
  • Single-photon detection technologies and timing electronics
  • Long-term stabilization of optical systems and experiments outside laboratory conditions
• Language Skills: Excellent command of English and/or German, both written and spoken, to ensure effective communication within a diverse team.

zerothird GmbH leads the field in quantum cryptography, based in Vienna and specializing in polarization-entanglement-based Quantum Key Distribution (eQKD). Our proprietary technologies, including the world’s most efficient entangled photon source, enable unmatched secure communication capabilities over both short and long distances. As the only provider of a fully connected eQKD network accommodating up to 10 users, and long-distance entanglement distribution over >300km, we are committed to redefining the standards of quantum communication security and reliability.

• Vibrant Quantum Community: Join a young and dynamic team where dialogue is fostered at all levels. Drink best Italian espresso while competing in the internal backgammon tournament.
• Family-Friendly Workplace: zerothird values the balance between work and family life. We understand and support the needs of working parents within our team, offering flexible working arrangements, part time possibilities and a culture of mutual support where family comes first.
• Exceptional Career Opportunities: As a startup at the forefront of rolling out unique quantum cryptography technologies worldwide, we offer unparalleled career growth opportunities. Whether in Austria or internationally, you’ll find a wealth of possibilities to advance and shape your career in an exciting, fast-evolving field.
• Inclusive Culture: Thrive in an authentic „Duz-Kultur“ where everyone is on a first-name basis, encouraging short decision-making processes and fostering a friendly, open office environment.
• Personalized Onboarding: Receive comprehensive introduction training, supported by a dedicated mentor to ensure a smooth transition and successful integration into our team.
• Daily Energizers: Enjoy complimentary amenities such as soft drinks, coffee, tea, fresh fruit, and ice cream to keep you refreshed throughout the day.
• Special Events: Participate in regular company activities including summer parties, and festive Christmas parties.

If you’re excited about joining a hands-on engineering team working on next-generation quantum technologies, we’d love to hear from you.The minimum gross salary for this position is €3.284,86 per month (based on full-time employment) in accordance with the collective agreement. However, there is a willingness to offer a higher salary depending on experience and qualifications.

We look forward to receiving your application!