Logo der Physikalisch-Technischen Bundesanstalt
MetroSommer 2023 - Dein genauester Sommer!

Projects 2023

Topic descriptions of the internship projects 2023

Project #01-2023: Lidar Measurements for Autonomous Driving Applications

In the field of Autonomous Driving (AD) a variety of sensors are used to scan the vicinity of the vehicle. Lidar (light detection and ranging) sensors are becoming an essential modality, since active photon scanning works under various lighting conditions (in contrast to cameras) and has relatively high resolution (in contrast to radar sensors).

The proposed project involves the evaluation of different lidar sensor characteristics, such as range, accuracy, resolution, and scan pattern, either in the laboratory or on our campus, using state-of-the-art lidar systems.

Your work is an important part in a series of measurement campaigns on the robustness of environmental sensing with lidar-based systems.

SupervisorDr. Sascha Meyne, Dr. Robert Wynands

Project #02-2023: Three-dimensional static sensitivity calibration of digital acceleration sensors

Project description: MEMS accelerometers, for example used in smartphones, are dynamically calibrated in our research group. Within the scope of the MetroSommer internship, a static calibration method for the three-dimensional characterization of the static sensitivity of the sensors will be tested and further improved. For this purpose, the sensors are precisely positioned in the earth's gravity field using an Euler cradle (a two-axis rotating device, see figure) and the three dimensional acceleration values are recorded. This is repeated automatically for many different angular positions. The direction-dependent sensitivities determined in this way will be visualized by using an evaluation routine which is to be written in Python and, if possible, will be approximated and compensated by suitable models. Basic knowledge of Python is required for this task.

SupervisorBenedikt Seeger, Leonard Klaus

Project #03-2023: Characterisation of rubber balls as sources for sound insulation measurement

The measurement of the sound insulation of buildings requires an appropriate excitation. Several methods are used: airborne excitation by loudspeakers, impact excitation by tapping machines, rubber balls or possibly other heavy hard objects. The amount of transmitted sound energy determines the quality of the insulation.

In this project of Metrosommer 2023, different rubber balls (and possibly further sources) will be characterised in a setup which is capable of measuring dynamic forces. The peak forces and the frequency content of the excitation will be analysed, also for different falling heights. The recording and analysing techniques will be realised with the support from the supervisors. 

In a second step, measurements in a building acoustic test facility for ceilings are planned to investigate the effect of different sources on the measurement of impact sound insulation.

SupervisorVolker Wittstock, Michael Kobusch

Project #04-2023: Numerical simulation and optimization of Josephson parametric amplifiers

At PTB we develop coherent superconducting quantum circuits, which form basic building blocks and enabling technology for quantum computers. These circuits are based on Josephson junctions and are operated at milli-Kelvin temperatures. The advertised project will focus on numerical simulation of parametric amplifier designs (Traveling-wave parametric amplifiers and/or Dimer Josephson-junction array amplifiers), which are built and measured in our group. You will use transient circuit analysis software (WRSpice) and develop existing python code to model the behavior of such circuits. Depending on progress, fitting of data from devices measured in our lab is a potential extra task. While in our lab, you can get hands-on experience in measurements of superconducting quantum circuits, such as qubits and Josephson parametric amplifiers. Ideally, but not required, applicants have prior knowledge in python and transient circuit analysis.

Topics covered: quantum technology, Josephson parametric amplifier, numerical simulation

SupervisorLukas Grünhaupt

Project #05-2023: Development of measurement setup for superconducting quantum circuits

At PTB we develop coherent superconducting quantum circuits, which form basic building blocks and enabling technology for quantum computers. These circuits are based on Josephson junctions and are operated at milli-Kelvin temperatures. We continuously devise new, and improve existing measurement setups. During the project you will be part of our team and work on setting up a new cryogenic DC-measurement setup and/or optimize an existing cryogenic RF-measurement setup. An experienced PhD student will be your daily supervisor with support from a senior scientist. The specific focus of the project can be tailored to your interests and prior knowledge. You will get hands-on experience in measurements of superconducting quantum circuits, a rapidly developing and expanding field.

SupervisorChristoph Kißling, Lukas Grünhaupt

Project #06-2023: Technical Cooperation with India for the Monitoring of Surface Water Quality

The Ganga is India’s spiritually most important river. At the same time, it is heavily polluted due to untreated wastewater. In 2014, the Indian Government thus launched the National Mission for Clean Ganga. With Indian and foreign aid funds, riverbanks were cleaned, sewage treatment plants constructed, and water quality monitoring efforts intensified. Commissioned by the Federal Ministry for Economic Cooperation and Development (BMZ), PTB is supporting the introduction of quality management systems and international good practices in the laboratory of two federal states in the Ganga basin. In the second project phase, this approach shall be further refined. Furthermore, it intends to better link the water monitoring institutions with the Indian Metrology Institute NPL (National Physical Laboratory). During the MetroSommer internship, a desk study to compare the Indian and German water monitoring system shall be prepared. The results will be integrated in future project activities.

The Ganga at Haridwar (Franziska Wende)

This project is ideally designed for an eight-week internship. For a four-week internship, the scope of the study will be reduced.

SupervisorUwe Miesner, Franziska Wende

Project #07-2023: Infrasound Calibration Tube

Infrasound produced by technical sources such as traffic, air conditioning and wind farms gets growing interest in noise assessment. Low-frequency measurement instrumentation is available on the market, but measurement results are not accepted by legal authorities and justice because the systems are not metrologically traceable to an acoustical infrasound standard. In this context, a setup for the characterization and calibration of measurement microphones has been designed and components have been prepared. The setup mainly consists of a tube providing two chambers, one with a loudspeaker for infrasound signal excitation and one for the reference and the microphone under test. By comparison, the microphone under test can be characterized and calibrated. As a feature, the small design of the tube allows to place it completely in a climatic chamber and thus to study environmental influences. 

The tasks of the project are to assemble the prepared setup, to test it and to perform first calibrations. As a possible extension, environmental studies can be done. 

The work will include assembling the setup, handling of electrical and acoustical measurement instrumentation, programming the measurement process (application level), measuring and analyzing results. 

Topics covered: Infrasound, calibration, measurement

Project #08-2023: Smart Display Reading

Automated measurement is a standard in modern laboratory practice. Almost every instrument provides at least one interface for computer assisted measurement control and data reading. Nevertheless, there are situations when reading a measurement value from a display is still necessary, such as during type approval of sound level meters because only the displayed value is the legally relevant measurement value. In this context, a simple automated display reading mechanism has been set up using a camera, basic image processing algorithms and a standard character recognition software. While the setup already successfully showed its basic functionality, the problem remains in legal applications that this kind of data reading must be highly reliable, and its uncertainty has to be quantified. The aim is to deliver a simple and robust automated system that identifies any displayed measurement value with a high and known success rate even under bad optical circumstances. 

The tasks of the project are to improve the image processing and character recognition algorithms written in Python, to test the system under real application conditions and to quantify the reliability by systematic testing and comparison to alternative reading mechanisms. 

The work will include programming in Python on beginner level, performing measurements in laboratory, developing and applying test procedures, and analyzing results. 

Topics covered: Measurement automation, character recognition, image processing, uncertainty

Project #09-2023: Sensitivities of the temporal light modulation (flicker) of LED-based lamps on their operation condition

The temporal light modulation (TLM) of LED-based lamps with electric ballast for operation at 230 V mains electricity is recorded by the transient luminance using a high-speed camera and by their transient illuminance using different flicker meters. By varying the operating conditions (mains voltage, mains frequency, ambient temperature, ...) of the LED-based lamps, different progressions can be investigated. The results of the different flicker meters can be compared with each other and discussed. From the results, statements can be made about the influence of the operating parameters on the TLM (flicker). These correlations are very important for the measurement uncertainty consideration of the TLM metrics and their properties in the field. The objective of this internship is to work out the dependence of the TLM (flicker) for a set of LED-based lamps on their operating conditions to initiate a discussion inside the joint research project EMPIR 20NRM01 MetTLM and Technical Committee TC 2-89 of the International Commission on Illumination (CIE).

An extension of the internship to 8 weeks is preferred.

Topics covered: Photometry, Light Emitting Diode (LED), Temporal Light Modulation, Temporal Light Artefacts

Project #10-2023: Laser links for optical clock comparisons

Reliable, long-time comparison of optical clocks at 10−18 fractional frequency uncertainty is one of the mandatory criteria on the roadmap towards a new, even more precise definition of the SI-second. In our working group, we develop techniques for high-precision optical frequency transfer across free space or through optical fibre to support future optical clock networks. Optical clock networks connected by phase-coherent links have enormous potential in basic and applied sciences such as geodesy, astronomy, and global navigation satellite systems. 

In this MetroSommer project, you will work alongside scientists to support the further development of our free-space and fibre optical links. You’ll learn about the challenges of “measuring” frequency more precisely than the current definition of the second. The focus of the project can be adjusted according to personal interests. One possibility would be to examine the influence of a variable signal amplitude and shape on the noise floor of our measurement systems, as we push to resolve the fundamental uncertainty limit of our links.

Topics covered: time and frequency metrology, laser optics, electronics

SupervisorJochen Kronjäger, Jingxian Ji, Ann-Kathrin Kniggendorf

Project #11-2023: Interferometry for the dissemination of the SI unit meter

Constantly increasing demands on manufacturing tolerances in industry necessitate new challenges for the precision of dimensional metrology. PTB meets this requirement by building interferometers that are unique in the world. This practical course is intended to give an insight into the field of interferometric length measurement. The content focus is set depending on personal interest and previous knowledge. Possibilities include:

Construction and characterization of a measuring station to determine the optical phase shift on surfaces

Validation and further development of measurement and evaluation programs

Modification of the distribution of optical wavelengths on a calibration system

Improvement and conversion of adjustment systems for measurement setups

Depending on the focus of the task, both experimental dexterity and programming knowledge are advantageous.

Topics covered: SI unit meter, imaging interferometry, optics and electronics

SupervisorTillman Neupert-Wentz, Dr. Guido Bartl

Project #12-2023: From photographical image to physical quantity

The visualisation of combustion and explosion processes is an important tool in explosion protection research. The complete chain from taking an image to the representation of a physical quantity has to be passed through. In metrology the measured quantities are often not the ones wanted, but they are in a close relation. Often a derivative is measured. To optain the quantity wanted, 2D integration by numerical methods is the choice

Starting with simple gradient and Schlieren images some methods for 2D integration shall be programmed and tested. IDL (interactive data language) as well  as GDL (GNU data language) will be used for programming. For the image processing already implemented algorithms will also be used as well as testing new ideas. To deduce a density or rather temperature field from a Schlieren image (image of the refractive index gradient) will be the goal.

If you are especially interested in numerical mathematics and programming this subject could be yours.

This subject is also suitable for an eight week internship.

Topics covered: explosion protection, combustion, Schlieren optics, image reconstruction, numerical mathematics and programming

Supervisor: Dr. Frank Stolpe, Dr. Arnas Lucassen

Project #13-2023: Quantum technology for experiments with trapped ions

Our research group at the QUEST (Quantum Engineering and Space-Time Research) Institute develops new methods of quantum technology. Our research focus is on laser spectroscopy of single trapped ions. The currently established techniques, e.g. for laser cooling of ions, can only be applied to few ionic species. However, we use techniques developed in the context of quantum information processing exploiting non-classical properties, such as quantum entanglement. This new approach allows us to perform spectroscopy of highly charged ions as well as molecular ions and to build an optical atomic clock based on a single aluminum ion.

The MetroSommer project is addressing the construction of an actively impedance-matched resonator. The resonator will later be used to operate a radio-frequency ion trap for the confinement of single calcium ions. The tasks offer the opportunity to acquire a wide range of skills. These include knowledge of radio-frequency engineering, the physics of trapped ions in Paul traps and electronic circuit design.

Supervisor: Lennart Pelzer, Fabian Wolf

Project #14-2023: Study on the repeatability of microwave connectors

When measuring signals at high frequencies, e.g. with vector network analyzers (VNAs), the connection repeatability of the used interface is an unavoidable contribution to measurement uncertainty. The repeatability depends mainly on the used connector type and the effective contact force, e.g. due to standardized torques for tightening the coupling nut. 

The task of the student is to investigate the dependency of the repeatability on the applied torque for different connector types under laboratory conditions. For this it is necessary to plan, carry out and evaluate several series of measurements. The focus is on new coaxial connectors used in communication systems, e.g. 5G.

Topics covered: VNA measurements, Measurement uncertainty, Repeatability

SupervisorKarsten Kuhlmann, Frauke Gellersen

Project #15-2023: Machine Learning for automated correction of vortex beams

Optical clocks based on the 2S1/2 -> 2F7/2 octupole transition in 171Yb+ are among the most accurate measuring devices worldwide. The natural lifetime of the excited 2F7/2 state of 1.6 years allows for long interaction times and leads to a low frequency instability for the clock. On the other hand, excitation with standard Gaussian laser beams require large light intensities, which leads to a shift in the transition frequency and can limit the clock performance. 

As recently demonstrated, the transition can also be efficiently driven using vortex beams, which have no optical intensity in the center of the beam profile. This requires strong focusing though and imaging errors can cause deviations from the desired profile.  As part of the internship, an adaptive optics system shall be realized in which a piezoelectrically deformable mirror and the use of machine learning can automatically compensate for disturbances in the beam shape. In the context of the internship, we thus provide an insight into current work in the field of quantum technologies, modern optics and automated machine learning.

Topics covered: Machine Learning, Adaptive Optics, Quantum Technologies, Optical Clocks

SupervisorMartin Steinel, Nils Huntemann

Project #16-2023: Increased quantum coherence via active suppression of magnetic field noise

Optical clocks based on single 171Yb+-ions are among the most precise in the world. They are used both as frequency standards and to investigate fundamental physics questions. Currently the first-order Zeeman insensitive mF=0 → mF=0 transitions are used for clock operation. However, first-order Zeeman-sensitive transitions offer interesting properties and could be used to suppress the quadrupole shift. To achieve long coherence times also on these transitions, suppression of magnetic field noise is key. The magnitude of a magnetic field oscillating at a specific frequency can be detected directly with a single ion using the quantum-lock-in technique. The goal of this project is to develop a setup for active stabilization of the magnetic field and to use it to suppress magnetic field noise, leading to increased coherence times on Zeeman-sensitive transitions. A feed-forward correction can be used to suppress e. g. the line noise at 50 Hz. The intern working on this project will gain hands-on experience in state-of-the-art experimental AMO physics. An extension of the internship to 8 weeks is preferred.

Topics covered: atomic physics, optical clocks, experimental physics

SupervisorMelina Filzinger, Nils Huntemann

Project #17-2023: Laser Spectroscopy with trapped ion Coulomb crystals

Ion trapping and laser cooling provide excellent experimental control of isolated individual atoms at energies down to the quantum mechanical ground state. The resulting access to an almost unperturbed internal level structure is the basis for some of the world’s most accurate atomic clocks, quantum sensors, and qubits with very long coherence times. With frequency resolutions at the 10-18 level, these systems are also interesting in the search for physics beyond the standard model and the investigation of relativistic effects at laboratory scales. Multiple ions in a common trapping potential arrange themselves into Coulomb crystals, which resemble small solid-state systems and can serve as spectroscopic references with enhanced signal-to-noise ratios or as qubit registers.

We use crystals of 115In+ and 172Yb+  ions in an atomic clock with a systematic uncertainty currently evaluated at the 10-18 level. Current efforts are focused on further improvements through an additional laser cooling stage and more precise characterization of atomic and environmental properties.

In this project, you can get involved in research at the intersection of quantum technology and fundamental science and gain insights into the work with trapped ions for precision spectroscopy, which involves manipulation of ion motion at the single-quantum level, laser technology and automated real-time control of advanced experimental sequences.

Topics covered: Laser spectroscopy, atomic clocks, quantum technology

Supervisor: Dr. Jonas Keller

Project #18-2023: Using ions as a sensor to benchmark novel ion traps for quantum technologies

The Quantum Technology Competence Center (QTZ) at the Physikalisch-Technische Bundesanstalt combines internationally recognized, professional competence in the field of quantum metrology and sensor technology with the mission to support industry in metrology as a governmental body. As part of the QTZ, we operate the user facility “Ion Traps” which is a central element to offer collaborators from industry and academia access to PTB’s quantum expertise.

Ion traps are an enabling platform for quantum technologies: owing superb control over trapped ions, being very sensitive quantum sensors, we benchmark novel ion trap technologies, e. g. by measuring the ion micromotion or heating rates. With this we evaluate ion traps as a key platform to be used in high-level experiments, such as quantum information and quantum computing.

During your MetroSommer project, you will engage with our research team on working with trapped ions, hands-on supporting ongoing works on the vacuum apparatus and involve yourself in the latest technological developments of ion trapping. 

Topics covered: Quantum technologies, ion trapping, vacuum technology, laser-cooling, laser-spectroscopy

SupervisorDr. André Kulosa, Prof. Tanja Mehlstäubler

Project #19-2023: Cryogenic silicon resonators

In our research group we develop lasers with the world's smallest line widths for use in optical clocks and for precision measurements. For this purpose, our research focus on extremely well isolated optical resonators. Their length stability is transferred to the frequency stability of the laser light. Besides technical noise sources such as vibrations and temperature changes, the fundamental length stability of the resonator is limited by Brownian motion - the so-called thermal noise - of the resonator components. We have several cryogenic silicon resonators in use and are permanently improving their performance. Among other things, we are currently working on an optimized cryo system for cooling the resonators to 124 K

In this internship you will work on laser systems with the world's narrowest line widths. You will help us to build and test a new cryo system and to investigate and further minimize the influence of technical disturbances like seismic vibrations. By frequency comparison with other ultra-stable lasers, we will determine the technical noise down to the thermal noise floor. According to your interests we can focus the project more to experimental work in the lab or to help us with programming and data analysis.

Topics covered: Optics & electronics, ultrastable lasers, optical clocks, cryo systems, quantum optics.

SupervisorDr. Thomas Legero, Dr. Sofia Herbers

Project #20-2023: Study on the impact of surface roughness on high frequency calibrations

In the primary calibration of vector network analyzers (VNAs), calculable primary standards such as air lines or terminations with different offset line lengths are used. In the metrological characterization of these standards, the conductivity of the material system and the prevailing surface roughness have a non-negligible influence on the frequency-dependent behavior. 

The student's task is to validate the methods used to determine the effective conductivity and surface roughness. For this purpose, suitable reference objects are to be investigated by calculating and measuring its frequency dependent behavior. In addition, the calculation method used can subsequently be further optimized or the observations extended to other measurement objects.

Topics covered: VNA measurements, VNA measurements, MATLAB coding, measurements uncertainty

SupervisorKarsten Kuhlmann, Andreas Schramm