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Roxanne Siadat

Roxanne Siadat


Roxanne Siadat is a Scientist in the Optical Frequency Metrology group. She joined NPL in September 2022, having completed an MSci degree at the University of Birmingham. Her master’s project focussed on modelling the uncertainty on the blackbody radiation shift in a strontium optical lattice clock. Prior to joining NPL she spent a year working in consultancy, where she gained further programming experience. 

As part of NPL’s femtosecond frequency comb team, Roxanne is working on Quantum Test & Evaluation (QT&E), funded through the UK’s National Quantum Technology Programme. For this project she is building new capability in radiofrequency and microwave clock characterisations by measuring their stability and accuracy against NPL’s primary frequency standard and, via the comb, against the next-generation Yb lattice optical clock. Through the National Measurement System (NMS) project covering redefinition of the SI second, she is also involved in performing high-resolution frequency measurements critical for the development of optical clocks, supporting the operation of the UK time scale, and enabling comparisons of optical and microwave standards both at NPL and at other national metrological institutes. 

Roxanne is a member of the Institute of Physics. 

Areas of interest 

  • The future redefinition of the second, supported by robust and reliable frequency comb systems 
  • High-resolution measurement of absolute frequencies and optical frequency ratios for optical clock comparisons 
  • Improving frequency stability of atomic clocks using combs for stability transfer between ultrastable laser sources and clock lasers 
  • Simulation of optical clock assemblies to help evaluate clock uncertainty 
  • Programming for data analysis, automation of data collection, and physical modelling 

Email Roxanne Siadat