QUANTUM-Seminar

Programm für das Wintersemester 2022/2023

Thursdays, 14 Uhr c.t.

Institut für Physik
IPH Lorentzraum 05-127

27.10.22Prof. Dr. hab. Wojciech Gawlik, Jagiellonian University, Poland
By simultaneous application of a laser and two microwave fields upon a spin system (e.g. NV centers in diamond) one can observe magnetic resonance structures with two-component, composite shapes of nested Lorentzians with different widths. One component is regularly power-broadened, whereas the linewidth of the other one undergoes field-induced stabilization and becomes power-independent. The observed stabilization appears to be a general phenomenon that occurs in open systems. It is caused by the competition between coherent driving and non-conservation of populations and can be interpreted in terms of specific bright and dark combinations of state populations. Bio: Studied physics at the Jagiellonian University in Kraków (MSc in 1970), 1972-74 worked in the Physikalisches Inst. der Uni Heidelberg (with G. zu Putlitz), PhD in 1975 (Uni Kraków). Longer research stays: Reading (GB) with G.W. Series, Munich with H. Walther, Paris with S. Haroche, Boulder with A. Gallagher, Berkeley with D. Budker. Head of the Atomic Optics Dept. (1990-94) and Photonic Dept. (2003-2017) in Jagiellonian Univ. (Kraków), since 2018 Professor Emeritus at the Institute of Physics Jagiellonian University.
14:00 Uhr s.t., IPH Lorentzraum 05-127

03.11.22Dr. Benjamin Stickler, Imperial College London, Dept. of Physics
Controlling the quantum dynamics of massive and complex objects, such as large molecules and nanoparticles, requires a detailed understanding of the interaction between their many interacting degrees of freedom and control fields. In this talk, I will discuss how light scattering induces non-reciprocal interactions between co-levitated objects [1], how the rotational quantum interference of nanoparticles with embedded nitrogen-vacancy centres gives rise to novel quantum phenomena [2,3], and how diffraction of chiral molecules can prepare superpositions of molecular configurations [4]. These examples illustrate the potential of macro-mechanical quantum systems for novel force and torque sensing schemes and for high-mass tests of quantum physics. [1] Rieser, Ciampini, Rudolph, Kiesel, Hornberger, Stickler, Aspelmeyer, and Delić, Tunable light-induced dipole-dipole interaction between optically levitated nanoparticles, Science 377, 987 (2022). [2] Stickler, Hornberger, and Kim, Quantum rotations of nanoparticles, Nat. Rev. Phys. 3, 589 (2021). [3] Rusconi, Perdriat, Hétet, Romero-Isart, and Stickler, Phys. Rev. Lett. 129, 093605 (2022). [4] Stickler, Diekmann, Berger, Wang, Phys. Rev. X 11, 031056 (2021). Short Bio: I studied Chemistry and Physics at TU Graz, and received my PhD in Physics form the University of Graz in 2013. I held postdoc positions at the University of Duisburg-Essen and at Imperial College London (as a Marie Sklodowska Curie Fellow). I obtained my Habilitation at the University of Duisburg Essen in 2022, where I now work on the theory of macroscopic quantum physics and levitated nanomechanics.. In 2022, I was elected into the NRW Academy of Sciences and Arts as a Young Fellow and I was recently admitted to the prestigious Heisenberg Programme by the DFG.
14:00 Uhr s.t., IPH Lorentzraum 05-127

10.11.22Dr. Anna Ermakova, MPI Mainz
Color centers in diamonds offer wonderful sensing possibilities in the case of the detection of magnetic or electric fields or temperature. Color centers in nanodiamonds can be incorporated into the biological systems to investigate them. One of the biggest advantages of quantum sensors based on nanodiamonds is that they operate at room temperature or higher. Therefore, they can be used to study living systems. We investigate how nanodiamonds can be brought into the living system in the most efficient way and what information we can get from them. Bio: Studied physics in Belarusian State University (MSc in 2011), PhD in physics (magna cum laude) with Fedor Jelezko at Ulm University, Institute for Quantum Optics (2011-2016). From 2017 to 2021 she held positions as a postdoc at Ulm University, researcher at Silicon Austria Lab GmbH, and a senior scientist at MPIP (Mainz). Since 2022 – Anna is Independent Group Leader at Max-Planck-Institute for Polymer Research, Mainz, Germany supported by Carl-Zeiss Foundation, her group works on investigating potential of Nanodiamonds for intracellular magnetometry and thermometry, novel all-optical sensing methods, and cell metabolism processes.
14:00 Uhr s.t., IPH Lorentzraum 05-127

24.11.22Dr. Lars von der Wense, LMU München
Optical atomic clocks are today’s most accurate time-keeping devices. They achieve stunning relative accuracies in the range of 10-18, corresponding to an error of 1 second in 30 billion years. An even improved accuracy is expected to be achieved by a nuclear optical clock, since the nucleus is significantly less sensitive to external influences than the atomic shell. Developing a nuclear optical clock requires laser spectroscopy of a nuclear transition, an objective which has so far not been achieved, but which has come into reach due to recent gain of knowledge. In this talk I will give an overview over the recent progress that has been made toward the development of a nuclear optical clock. I will introduce several experiments that are currently in preparation aiming toward first-time laser spectroscopy of a nuclear transition. Finally, I will introduce the investigations planned within the framework of the newly funded BMBF project “NuQuant”.
14:00 Uhr s.t., IPH Lorentzraum 05-127

01.12.22Dr. Masaki Hori, MPI für Quantenoptik, Garching/Institut für Physik, Uni Mainz
A Metastable antiprotonic helium is a Rydberg exotic atom composed of a helium nucleus, electron, and an antiproton. It is among the hadron-anti- hadron bound systems with the longest known lifetimes. Intense beams of laser light can be used to excite atomic transitions involving the anti- proton orbital. By utilizing sub-Doppler two-photon laser spectroscopy or buffer gas cooling, its atomic transition frequencies were measured to ppb-scale precision. Comparisons with the results of QED calculations allowed the antiproton-to-electron mass ratio to be determined as 1836.1526734(15). The results were used to set upper limits on fifth forces between antiprotons and nucleons at atomic length scales, and on forces that may arise between an electron and antiproton mediated by hypothetical bosons by Mainz theoretical groups. Efforts are currently underway to improve the experimental precision using CERN’s ELENA facility. We also observed narrow spectral lines of these atoms formed in super fluid helium with asurprisingly high spectral resolution of 2 parts per million. This revealed the hyperfinestructure arising from the spin-spin interaction between the antiproton and electron,despite the fact that the atom was surrounded by a dense matrix of normal atoms. Thisphenomenon may imply future possibilities in condensed matter or astrophysical fields. Metastable pionic helium (πHe+) contains a negative pion occupying a state of n≈l-1≈17, and retains a 7 ns average lifetime. We recently used the 590 MeV ringcyclotron facility of Paul Scherrer Institute near Zurich to synthesize the atoms, and irradiated them with resonant infrared laser pulses. This induced a pionic transition within the atom and triggered an electromagnetic cascade that resulted in the π- being absorbed into the helium nucleus. This constitutes the first laser excitation and spectroscopy of an atom containing a meson. By improving the experimental precision, the pion mass may bedetermined to a high precision as in the antiproton case. We wish to extend these studies to other atoms containing kaons or hyperons that includes the strange quark. Bio: Masaki Hori obtained his PhD in 2000 at the University of Tokyo in the field ofnuclear physics. After CERN and JSPS fellowships in Geneva involving antiprotonexperiments and building LHC injector parts, he became group leader at the Max Planck Institute of Quantum Optics in 2008. He obtained a Habilitation and became Privatdozent in 2020 at the Ludwig Maximillians University, while working in a commercial company that develops optical frequency combs. He joined the Institute of Physics of Mainz today as a Heisenberg position. He is spokesperson of the laser spectroscopy experiments of exotic helium atoms at CERN and PSI.
14:00 Uhr s.t., IPH Lorentzraum 05-127

08.12.22Dr. Nikita Kavokine, MPI for Polymer Research, Mainz
Liquids are usually described within classical physics, whereas solids require the tools of quantum mechanics. I will show how in nanoscale systems this distinction no longer holds. At these scales, liquid flows may in fact exhibit quantum effects as they interact with electrons in the solid walls. I will first discuss the quantum friction phenomenon, where charge fluctuations in the liquid interact with electronic excitations in the solid to produce a hydrodynamic friction force. Using many-body quantum theory, we predict that this effect is particularly important for water flowing on carbon-based materials, and we obtain experimental evidence of the underlying mechanism from pump-probe terahertz spectroscopy. I will then show how the theory can be pushed one step further to describe hydrodynamic Coulomb drag – the generation of electric current by a liquid in the solid along which it flows. This phenomenon involves a subtle interplay of electrostatic and electron-phonon interactions, and suggests strategies for designing materials with low hydrodynamic friction. Bio: Nikita Kavokine obtained a Bachelor in Chemistry and a Master in Theoretical Physics from Ecole Normale Supérieure (ENS) in Paris. He continued at ENS for his PhD, in the group of Prof. Lydéric Bocquet, working on both theory and experiments in nanoscale fluid dynamics. He then obtained a Flatiron Research Fellowship and spent a year in New York, learning advanced numerical methods for condensed matter systems. He is now a postdoctoral fellow at the Max Planck Institute for Polymer Research. His research is at the interface between ‘hard’ and ’soft’ condensed matter, focussing on the quantum behavior of liquids near solid surfaces.
14:00 Uhr s.t., IPH Lorentzraum 05-127

15.12.22Dr. Boris Naydenov, Helmholtz Zentrum Berlin
Electron Paramagnetic Resonance (EPR) is a well established technique with wide applications in various scientific fields, but with limited spin sensitivity. Here two approaches for measuring small ensembles of electron spins will be presented. In the first part of the talk a miniaturized EPR spectrometer based on a single chip (EPRoC) will be introduced, where the sample volume can be reduced down to few nanolitres. Recent results using rapid frequency sweeps for detection will be shown, which improve the signal to noise for samples with long relaxation times. In the second part of the talk Optically Detected Magnetic Resonance (ODMR) on Nitrogen-Vacancy centers (NVs) in diamond nano-structures will be shown. The NVs can be detected and controlled at the single spin level and they are well studied physical systems as they are very promising quantum sensors and qubits. The presented experiments with NV ensembles are the first steps towards the realization of a unforgeable quantum token, which is protected by the quantum non-cloning theorem.
14:00 Uhr s.t., IPH Lorentzraum 05-127

22.12.22Dr. Sven Sturm, MPI für Kernphysik, Heidelberg
Experiments with single ions confined in a Penning trap enable access to a broad range of observables that are of fundamental importance for our understanding of fundamental physics. In the magnetic field of the trap, the cyclotron frequency of an ion can be determined with unique precision and gives direct access to the charge-to-mass ratio. Furthermore, we have access to the gyromagnetic g-factor via a measurement of the (Larmor) spin precession frequency. This way, we have determined a number of fundamental parameters, such as the electron, proton, neutron and deuteron atomic masses with leading precision. This way, in our new generation experiment ALPHATRAP we have recently measured the g-factor of highly charged, hydrogenlike 118Sn. A comparison to a precise prediction by quantum electrodynamics (QED) allows probing the validity of QED in extreme electric fields, in the order of 1015 V/cm. Furthermore, by crystallizing two ions simultaneously in one trap we have achieved a leap of two orders of magnitude on the precision frontier. With this new technique, we have recently determined the isotopic effect of the g-factor in hydrogenlike neon ions, at 13 digits precision with respect to g and are consequently sensitive to previously invisible contributions, such as the QED recoil, and can set limits on hypothetical new physics such as dark matter mediated couplings. Finally, the possibility to determine the internal state of a single ion gives us access to systems that were previously difficult to handle, such as the molecular hydrogen ions. Currently, we are performing spectroscopy on HD+ and soon H2+. The development of the necessary toolbox will be a seminal step towards a possible future spectroscopy of the antimatter equivalent, anti-H2-, which will enable a unique test of charge-parity-time (CPT) reversal symmetry.
14:00 Uhr s.t., IPH Lorentzraum 05-127

05.01.23Prof. Dr. Nir Bar-Gill, Hebrew University, Jerusalem, Israel
The study of open quantum systems, quantum thermodynamics and quantum many-body spin physics in realistic solid-state platforms, has been a long-standing goal in quantum and condensed-matter physics. In this talk I will address these topics through the platform of nitrogen-vacancy (NV) spins in diamond, in the context of purification (or cooling) of a spin bath as a quantum resource and for enhanced metrology and sensing. I will first describe our work on characterizing noise using robust techniques for quantum control ([1], in collaboration with Ra’am Uzdin). Suppression of such noise can be related to control and cooling of the spin-bath surrounding the NV, using a single optically pumped NV quantum central spin as a refrigerator [2]. I will then present a general theoretical framework we developed for Hamiltonian engineering in an interacting spin system [3]. This framework is applied to the coupling of the spin ensemble to a spin bath, including both coherent and dissipative dynamics [4]. Using these tools I will present a scheme for efficient purification of the spin bath, surpassing the current state-of-the-art and providing a path toward applications in quantum technologies, such as enhanced MRI sensing. Finally, if time permits, I will describe our work in using NV-based magnetic microscopy to implement quantum sensing in various modalities. I will present measurements of 2D vdW magnetic materials, and specifically the phase transition of FGT through local imaging of magnetic domains in flakes of varying thicknesses [5], as well as a technique for sensing radical concentrations through the change in the charge state of shallow NVs ([6], in collaboration with Uri Banin). 1. T. Zabelotsky et. al., in preparation. 2. P. Penshin et. al., in preparation. 3. K. I. O. Ben’Attar, D. Farfurnik and N. Bar-Gill, Phys. Rev. Research 2, 013061 (2020). 4. K. I. O. Ben’Attar et. al., in preparation. 5. G. Haim et. al., in preparation. 6. Y. Ninio et. al., ACS Photonics 8, 7, 1917-1921 (2021).
14 Uhr c.t., IPH Lorentzraum 05-127

12.01.23Dr. Andreas Mooser, MPI für Kernphysik, Heidelberg
The hyperfine structure of hydrogen like ions are a unique probe to access nuclear magnetic moments and nuclear structure. Thus, while eliminating the ignorance of essential links in metrology due to insufficiently known magnetic moment, at the same time these ions provide complementary insight into the inner nucleus. The very recently started ³He experiment exploits these characteristics to provide a new standard for absolute precision magnetometry and determine the nuclear charge and current distribution of ³He. To this end, a novel four Penning trap experiment was designed and built. Using novel techniques, this system enables non demolition measurements of the nuclear quantum state and allows sympathetic laser cooling of single, spatially separated ions to sub-thermal energies [1]. In the first measurement campaign, ³He was investigated by exciting microwave transitions between the ground state hyperfine states. This enabled us to determine the nuclear g-factor, the electronic g-factor and the zero field ground state hyperfine splitting of ³He with a precision of 5*10 -10, 3*10 -10 and 2*10 -11, respectively [2]. Our measurement constitutes the first direct and most precise determination of the ³He nuclear magnetic moment. The result is of utmost relevance for absolute precision magnetometry, as it allows the use of He NMR probes as an independent new standard with much higher accuracy. In addition, the comparison to advanced theoretical calculations enables us to determine the size of the ³He nucleus with a precision of 2.4*10 -17 m. In future, we aim at a direct determination of the bare nuclear magnetic moment of ³He to be compared to the bound state result. For this measurement, it is essential to implement new methods and technology such as sympathetic laser cooling and a high precision voltage source based on Josephson junctions [3]. The latest results, status and the future prospect of the experiment will be presented. References [1] A Mooser et al., J. Phys.: Conf. Ser. 1138, 012004 (2018) [2] A. Schneider et al., Nature 606, 878 (2022) [3] A. Schneider et al., Ann. Phys. 531, 1800485 ( 2019)
14 Uhr c.t., IPH Lorentzraum 05-127

19.01.23Prof. Giuseppe Vallone, University of Padova, Italy
Within the last two decades, Quantum Technologies have made tremendous progress, from proof of principle demonstrations to real life applications, such as Quantum Key Distribution (QKD) and Quantum Random Number Generators (QRNGs). Here, we first briefly review the basic principles of QKD and QRNGs. We then discuss the results that we have recently obtained in our group at the University of Padova towards the realization of ultra-fast and secure QRNGs and mature and efficient QKD systems. Prof. Giuseppe Vallone is an Associate Professor at University of Padua since 2019 (www.dei.unipd.it/~vallone) and co-founder and CTO of ThinkQuantum (www.thinkquantum.com), a spin-off of the Univeristy of Padua pioneering a new generation of secure communication systems based on quantum technology. His research is focused on quantum information, photonic states, quantum communication, quantum random number generators and Orbital Angular Momentum states. He has three patents and more than 130 publications in the area of quantum optics and quantum information. He is currently the coordinator of the European Project QUANGO (www.quango.eu) and the Italian Project QUASAR (quasar.dei.unipd.it).
14:00 Uhr s.t., IPH Lorentzraum 05-127

26.01.23Prof. Vahid Sandoghdar, Max-Planck-Institut für die Physik des Lichts, Erlangen
Laboratory manipulation of single quantum emitters and single photons has matured to a routine procedure over the past two decades. These activities have led to new emerging topics such as optomechanical functionalities and coherent cooperative interactions among several quantum emitters. In this presentation, I discuss our efforts of the last decade in coupling molecules to high-finesse Fabry-Perot cavities and nanoscopic waveguides on a chip, demonstrating dipole-induced transparency, strong coupling and single-photon nonlinearity. Moreover, I present data on precision spectroscopy of the vibronic transitions in single molecules as well as theoretical conception of hybrid optomechanical platforms for achieving long coherence and storage times. I will also present the latest results on the coupling of two or molecules to each other via a common mode of a micro-resonator.
14 Uhr c.t., IPH Lorentzraum 05-127

02.02.23Prof. Stephan Schiller, Heinrich-Heine-Universität Düsseldorf, Institut für Experimentalphysik
Molecular hydrogen ions (MHI), the simplest molecules, are three-body quantum systems composed of two simple nuclei and one electron. They are of high interest for fundamental physics and metrology because they provide the missing link between the fields of mass and g-factor measurements with Penning traps and spectroscopy of hydrogen-like atoms. Basically, the new ingredients introduced by the MHI are the long-range nucleus-nucleus interaction, absent in the hydrogen atom, and the quantized motion of the nuclei. Precision spectroscopy of the MHI can thus furnish novel results: (1) on the masses of proton and deuteron (in the future, also of tritium), (2) set limits for beyond-Standard-Model (BSM) forces, (3) verify the wave character of matter, and (4) test alternative theories of quantum mechanics. This is performed by comparing or matching experimental and theoretical rotational and/or vibrational frequencies. The comparison is enhanced by the availability of several recently measured transition frequencies and recent advances in ab initio theory. An additional opportunity for probing the interactions between the particles within the MHI is the precision measurement of its hyperfine structure (HFS). Only the synthesis of the HFS of the hydrogen atom, of the deuterium atom and of the molecular hydrogen ion allows probing the physics of HFS at the finest level, resolving the issue of the uncalculable nuclear contributions. We present recent results of our spectroscopy of sympathetically cooled MHI, its results and interpretation. An outlook on near-future studies is also given.
14 Uhr c.t., IPH Lorentzraum 05-127

zukünftige Termine
09.02.23Prof. Dr. Immanuel Bloch, Max-Planck-Institute of Quantum Physics, Garching
TBA
14:00 Uhr s.t., IPH Lorentzraum 05-127

Koordination: Kontakt:

Dr. Christian Smorra
Institut für Physik
chsmorra@uni-mainz.de

Dr. Danila Barskiy
Institut für Physik und HIM Mainz
dbarskiy@uni-mainz.de

Andrea Graham
Institut für Physik
graham@uni-mainz.de