Senior RF Engineer (Qrf)

Infleqtion is a global quantum technology company solving some of the world's most challenging problems. We build and integrate quantum computers, sensors, and networks. From fundamental physics to leading-edge commercial products, Infleqtion enables "quantum everywhere" through an ecosystem of devices and platforms.

Quantum Spectrum, also known as QRF, develops fieldable radio-frequency sensing systems based on Rydberg atoms. The team combines atomic physics, lasers and photonics, RF electronics, embedded controls, software, and precision hardware to turn laboratory prototypes into repeatable, integrated sensing systems.

Position Summary

Infleqtion is seeking a hands-on Senior RF Engineer to establish and own the RF and electromagnetics discipline within the QRF team. Reporting to the QRF Product Engineer, this engineer will lead the design, modeling, integration, calibration, and verification of broadband RF hardware and test environments. The work centers on calibrated electromagnetic field generation and delivery, sensor interfaces, low-noise signal chains, RF structures, and traceable measurement-not the modem, protocol, or network design typical of a conventional communications role. Prior quantum experience is not required, but the successful candidate must be able and motivated to learn the atomic physics and Rydberg sensing principles needed to make sound RF design decisions.

Job Responsibilities

The duties and responsibilities below describe the essential functions of the role. Depending on business needs, the position may perform some or all these duties. Duties, responsibilities, and activities may change, or new ones may be assigned at any time with or without notice.

• Own RF and electromagnetic requirements, architectures, interfaces, performance budgets, and verification methods for QRF sensor heads, test systems, and integrated hardware.
• Design, simulate, build, and characterize RF structures such as electrodes, resonators, antennas, fixtures, interconnects, shielding, and field delivery hardware.
• Develop RF signal generation, amplification, filtering, frequency conversion, local oscillator, distribution, and analog interface approaches that support broadband sensor operations
• Build and improve controlled conducted and radiated RF test environments, including field generation, field mapping, and calibration configurations.
• Define and execute measurements for field strength, frequency response, impedance, insertion and return loss, phase, coupling, shielding, noise, linearity, dynamic range, spurious response, and uncertainty.
• Build and maintain RF performance budgets for gain, loss, noise, phase noise, leakage, coupling, compression, harmonics, spurious signals, and other limits that affect sensor performance.
• Lead RF hardware bring-up, characterization, troubleshooting, and root-cause analysis across benchtop, subsystem, sensor head, and integrated system configurations.
• Use electromagnetic and circuit simulation to guide hardware and test fixture design, component selection, design trades, and interpretation of measured results; reconcile models with laboratory data.
• Develop Python or comparable automation for instrument control, parameter sweeps, calibration, regression testing, data analysis, and technical reporting.
• Work with applied physicists to relate RF field delivery and signal-chain behavior to atomic response, sensitivity, bandwidth, stability, dynamic range, and repeatability.
• Collaborate with optical-mechanical, electrical, embedded-systems, software, manufacturing, and technician personnel to define interfaces, resolve cross-domain problems, and transfer RF designs into repeatable builds and acceptance tests.
• Document designs, models, interfaces, calibration methods, test procedures, configurations, results, trade studies, risks, and recommendations for technical reviews, verification, and future production.