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  • Dr. Allan Stewart Johnson

    Position: Assistant Research Prof. (tenure track)
    Research: Ultrafast Science of Quantum Materials
    ORCID: 0000-0002-0711-708X
    Google Scholar profile: https://scholar.google.co.uk/citations?user=r79SSoYAAAAJ
    Joining Date: January, 2023
    User Name: allan.johnson
    Stewart Johnson

    Dr. Johnson joined IMDEA Nanociencia as a “Ramon y Cajal” Assistant Research Professor in 2023, heading the Ultrafast Science of Quantum Materials group. Prior to that he was based at ICFO – The Institute of Photonic Science in Barcelona, where he was a “La Caixa” Junior Leader at from 2021-2022, and a PROBIST Marie Curie postdoctoral fellow from 2018-2021. He completed his PhD on tabletop attosecond x-ray laser sources at Imperial College London in 2017, where he was a Marie Curie doctoral fellow and NSERC PGS award holder, and his B.Sc. In Physics-Mathematics at the University of Ottawa in 2013.


  • Dr. Arnab Sarkar

    Position: Postdoctoral Researcher
    ORCID: 0000-0002-5348-0699
    Google Scholar profile: https://scholar.google.com/citations?user=Vbl4fRkAAAAJ
    Joining Date: 2023
    User Name: arnab.sarkar

    Arnab joined the USQM group as a post-doctoral fellow in July 2023, following the completion of his doctoral thesis titled "Classical Discrete Time Crystal" at the Indian Institute of Technology Kanpur. His doctoral work focused on the mechanical properties of NEMS and MEMS. He completed his MSc (2015 -2017) at the Indian Institute of technology Bombay and BSc (2012-2017) at Ramakrishna Mission Vidyamandira.


  • María Recasens Esparraguera

    Position: PhD Researcher
    Research: Ultrafast Science of Quantum Materials
    ORCID: 0000-0002-1134-3901
    Recasens Esparraguera

    Maria graduated in Physics at Universitat de Barcelona in 2021. She got a Master in Quantum Science and Technology in a joint program from Universiat de Barcelona, Universitat Autònoma de Barcelona and Universitat Politècnica de Barcelona in 2022. During her master she worked with light induced superconductivity and coherent control at ICFO.  Since October of 2022 she is a PhD student based at ICFO in the group of Maciej Lewenstein and co-supervised by Dr. Johnson at IMDEA.

  • Shreya Bagchi

    Position: PhD Researcher
    Joining Date: July 2023
    User Name: shreya.bagchi

    Shreya obtained her B.Sc. degree in physics at Ravenshaw University (India) and her M.Sc. degree in Physics with a specialisation in Laser Physics at Pondicherry University (India). Prior to joining IMDEA Nanociencia, she had experience working in the field of laser cooling of neutral atoms while she was at the Raman Research Institute, India. She joined IMDEA Nanociencia in July 2023 as a PhD student to study photoinduced phase transitions and non-linear optics in quantum materials. When not in the lab, she likes to read novels and paint.

  • Dr. Ricardo Rojas

    Position: Postdoctoral researcher
    Joining Date: March, 2024

    Ricardo joined the USQM group in March 2024. In his academic training he has sought to develop a robust basis for the characterization of materials using ultrafast spectroscopy both in his master's and doctoral studies. In his master studies at the Pontificia Universidad Católica de Chile he developed together with collaborators the only non-interferometric FROG-based system that reconstructs fs-pulses analytically. In his PhD at the University of Luxembourg he started with his colleagues with the implementation of the ultrafast condensed matter physics laboratory, developing systems that allow tuning of broad spectrum pulses in the ranges from 400 to 1600nm, tens of THz and few THz, as well as developing Pump Probe type experiments on semiconductors. Ricardo has come to IMDEA Nanociencia with the idea of learning about different types of materials, phenomena and perspectives in ultrafast spectroscopy.

  • Ahsan Ali

    Position: PhD researcher
    Joining Date: February, 2024

    Ahsan Ali was born in Pakistan. His academic journey commenced at the University of Sargodha, (Pakistan) where he completed his bachelor’s degree in physics in 2018. He pursued his Master of Philosophy (MPhil) degree in Physics at Quaid-i-Azam University, Islamabad, Pakistan in 2022, a prestigious institution that is consistently ranked as the number one university in the country. His journey in physics led him to the National Institute of Lasers and Optronics (NILOP), Pakistan's foremost institute for laser research. There, he specialized in "Terahertz Time-Domain Spectroscopy" and undertook a significant research endeavour with his thesis, titled "Discrimination of hydrated salt using terahertz time-domain spectroscopy." He joined IMDEA Nanociencia in February 2024 as a PhD student in the Ultrafast Science of Quantum Materials group led Prof Dr Allan Johnson. He likes to play cricket and Badminton in his free time and loves to travel to different places.