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Team

Standing (left to right): Sergey Lotkhov, Michel Schröder, Victor Gaydamachenko, Fabian Kaap, Marat Khabipov
Sitting (left to right): Judith Felgner, Lukas Grünhaupt, Christoph Kißling, Asen Lyubenov Georgiev

Dr. Lukas Grünhaupt

Lukas was raised in a small town north of Karlsruhe, Germany but moved to the 'big' city to study physics. He graduated from Karlsruhe Institute of Technology (KIT) with a Master's thesis about 3D transmon quantum bits in 2016. Afterwards he joined Dr. Ioan M. Pop's Black Forest Quantum Lab (BFQ) at KIT to continue working on superconducting quantum circuits with a focus on harnessing the kinetic inductance and intrinsic non-linearity of granular aluminum (grAl). In 2019 he defended his PhD thesis about granular aluminum superinductors. One of the major results during his three years in the BFQ-lab was the fabrication of a fluxonium qubit with a shunting inductance entirely made from a strip of grAl. After a brief postdoc stint at KIT, Lukas joined the lab of Professor Leo P. Kouwenhoven at QuTech (TU Delft, Netherlands) to build on his background in cQED and add the intricacies of semiconductor-superconductor Josephson junctions into the mix. Since 2022 Lukas is part of the quantum electronics department at PTB and heads working group 2.42 since 08/2022.

Permanent Staff

Dr. Sergey Lotkhov

Sergey Lotkhov has been involved in experimental research of Coulomb blockade related phenomena in small Josephson junctions. He is a co-author of about 45 publications and 50 presentations in the field of single-charge pumping, both in normal-conducting and in superconducting devices, and photon-assisted tunneling effects. His skills include a wide scope of nanofabrication techniques related to sub-µm-scale tunnel junctions based on aluminium as well as making measurements in a dilution fridge below 100mK.

Judith Felgner

Judith Felgner was born and raised in Grimma and studied Applied Sciences at TU Bergakademie Freiberg. Since 2015 she is part of the Quantum Electronics group at PTB. Her main activity is fabrication of micro- and naonelectronic circuits in PTB's clean room center.

Michel Schröder

Michel was born in Braunschweig and grew up in small-town Wendeburg, where he still lives today. After finishing school he started training as a precision mechanic at PTB. Since successfully completing his training in 2014 he was involved in multiple projects at PTB and joined the quantum electronics department in 2017. Certainly one of the highlights in his career to date was the Avogadro project, in which Michel was part of the team building the silicon sphere to replicate the original kilogram ("Urkilogramm"). In parallel to working at PTB Michel continued his education and graduated from Teutloff Technische Akademie in 2020 as an engineer specializing in industrial engineering.

Postdocs & PhD Students

Bhoomika R Bhat

Bhoomika R Bhat was born in September 1999. She was brought up in Bangalore, India. In 2022, she graduated with M.Sc. Physics. Her interest is on Superconducting Quantum Devices. She joined Indian Institute of Science(IISc) under Prof. Vibhor Singh as a project assistant. While working for a year, she learnt fabrication methods involved in making supercondcuting qubits and some JPAs. Since July 2023, Bhoomika is a part of working group 2.42 at PTB. She aims to study and develop Dimer Josephson Junction Array Amplifiers (DJJAAs). She loves to watch movies, read novels and walk in her free time

Li Wei Chang

Li Wei was born in Taiwan, a beautiful island. He pursued his studies in Physics at National Tsing Hua University, where he earned both his bachelor's and master's degrees. During his master's program, he delved into surface science, utilizing Scanning Tunneling Microscopy under the guidance of Professor Pin Jui Hsu. Following graduation, Li Wei took on roles as a research assistant at both National Taiwan University and Academia Sinica. At Academia Sinica, he was responsible for the measurement and operation of five-qubit chips, where he developed two-qubit gate randomized benchmarking and  cryoscope technology. Upon completing the five-qubit project, Li Wei joined PTB in May 2024, focusing on the design and enhancement of generalized flux qubits.

Victor Gaydamachenko

Victor was born and raised in Moscow, Russia. He received his Bachelor and Master degree in Physics from Lomonosov Moscow State University. For his Master's thesis he worked on the fabrication of molecular single-electron transistors. He joined the department of quantum electronics at PTB Braunschweig in 2019 and is now working on the development of three-wave mixing Josephson Traveling-Wave parametric amplifiers (JTWPA).

Asen Lyubenov Georgiev

Asen was born in Pleven, Bulgaria in 1996. He moved to Giugliano, close to Naples, Italy at the age of 10. Asen graduated in Condensed Matter Physics from the University of Naples Federico II with a Master’s thesis entitled “Principles and characterization of superconducting single- and two-qubit gates”. While working on his thesis, Asen got hands on experience with superconducting qubits and developed an understanding of how to operate and measure them. Since December 2022 he is part of working group 2.42 at PTB Braunschweig, where he is currently working on the QSolid project with the goal of developing superconducting qubits and related measurement techniques.

Fabian Kaap

Fabian started studying physics in 2014 at Heidelberg university and graduated with a M.Sc. in 2020. For his Master's thesis he investigated the low frequency excess flux noise of dc-SQUIDs made for the readout of cryogenic detectors. In early 2021 he started as a PhD candidate at PTB and is performing research on Bloch oscillations since. The goal of his project is to observe dual Shapiro steps, which could enable a new kind of current standard. When he is not at PTB, he enjoys physical activities like hiking in the Harz mountains, skating in the Prinzenpark and attending the gym.

Christoph Kißling

Christoph grew up in the beautiful countryside of southern Germany. He worked as an electronics technician for three years, and as an electronics teacher at Diguna Rainbow Polytechnic, Kenya, for one year before he attended university. In 2018 he received his M.Sc in Electrical Engineering and Information Technology from Ilmenau University of Technology. He joined the working group in 2018 as a PhD student in Electrical Engineering and is currently working on the development of Josephson traveling-wave parametric amplifiers.

Daniel Alejandro Valenzuela Henriquez

In 2012 Daniel started working in the Planetary Exploration Laboratory of Universidad de Chile, where the project SUCHAI (first nano-satellite build in Chile) was built. There, he worked on a communication system between the ground station and the next generations of satellites. In 2015 he worked in the molecular electronic laboratory at the university. Since 2016 he has been working on the design of parametric amplifiers as an undergraduate student. In this topic Daniel obtained his master’s degree in engineering sciences in 2021. Furthermore, he is continuing this research in his Ph.D. studies, developing research for the next generation of kinetic inductance parametric amplifiers. Daniel joined PTB as a postdoc in April 2024.

Undergraduate Students & Interns

You

We are always looking for enthusiastic, motivated, and ambitious students to join our team. There are multiple projects available, which cover different aspects of coherent superconducting quantum circuits. If you are interested in joining us for an internship, Bachelor, or Master thesis don't hesitate to send an email to Lukas (lukas.gruenhaupt@ptb.de).

Alumni

Permanent staff

Dr. Marat Khabipov

Interns

Selim Lariani (2022)

Mina Mohseni (2022)

Antoine Andrieux (2023)

Leopold Weinand (MetroSommer 2023)

Hejie Zhu (MetroSommer 2023)