Research Highlights from 2016 - 2020

Title, Journal: Tunneling dynamics between superconducting bound states at the atomic limit, Nature Physics 16, 1227 (2020) What?: An international collaboration of scientists between the Max-Planck-Institute for Solid State Research in Stuttgart, Ulm University and the Autonomous University of Madrid has now found a minimal configuration for producing an electronic current. Using a scanning tunneling microscope to couple two individual energy levels at the atomic scale, they show that a small current can flow between them, one electron at a time. Who?: IQST Fellow Joachim Ankerhold from Institute of Complex Quantum Systems @UUlm, Klaus Kern and Christian Ast from MPI Stuttgart. Read more
Title, Journal: Ultrafast vector imaging of plasmonic skyrmion dynamics with deep subwavelength resolution, Science - Published 24 April 2020 What?: Plasmonic skyrmions are an optical manifestation of topological defects in a continuous vector field. Identifying them requires characterization of the vector structure of the electromagnetic near field on thin metal films. Researchers at the Universities of Stuttgart and Duisburg-Essen and the University of Melbourne (Australia) have now succeeded for the first time in filming these vortex patterns on the nanometer scale. Who?: IQST Fellow Harald Giessen from 4th Institute of Physics @University of Stuttgart and IQST Guest Researcher Tim Davis from University of Melbourne Read more
Title, Journal: Absence of a Dissipative Quantum Phase Transition in Josephson Junctions, Phys. Rev. X 10, 021003 – Published 3 April 2020 What?: The Josephson junction has become the most important nonlinear quantum electronic component at our disposal. A team of researchers from the National Research Centre CEA Saclay (Paris) and the Universities of Ulm and Freiburg has now investigated this quantum phase transition in a superconducting circuit. They show that a Josephson junction connected to a resistor does not become insulating beyond a given value of the resistance due to a dissipative quantum phase transition, as is commonly believed.  Who?: IQST Fellow Joachim Ankerhold from Institute of Complex Quantum Systems @UUlm Read more
Title, Journal: Heat rectification via a superconducting artificial atom, Nature Communications Physics volume 3, Article number: 40 (2020)– Published 25 February 2020 What?: In developing technologies based on superconducting quantum circuits, the need to control and route heating is a significant challenge in the experimental realisation and operation of these devices. In this theoretical and experimental work with colleagues from Finland it is shown for the first time that heat flows can be rectified at quantum mechanical level. Who?: IQST Fellow Joachim Ankerhold from Institute of Complex Quantum Systems @UUlm Read more
Title, Journal: A CMOS NMR needle for probing brain physiology with high spatial and temporal resolution, Nature Methods – Published 25 November 2019 What?:  Description of a monolithically integrated NMR-on-a-chip needle that combines an ultra-sensitive 300 µm NMR coil with a complete NMR transceiver, enabling in vivo measurements of blood oxygenation and flow in nanoliter volumes at a sampling rate of 200 Hz. Who?: IQST Fellow Jens Anders from Institute of Smart Sensors @Uni Stuttgart Read more
Title, Journal: The low-energy Goldstone mode in a trapped dipolar supersolid, Nature – Published 09 September 2019 What?: A research team led by Tilman Pfau and Tim Langen at the 5th Institute of Physics of the University of Stuttgart has succeeded in proving experimentally that the long-sought supersolid state of matter exists. Who?: IQST Young Researcher Tim Langen from 5th Institute of Physics @UniStuttgart Read more
Title, Journal: Precision Spectroscopy of Negative-Ion Resonances in Ultralong-Range Rydberg Molecules, Phys. Rev. Lett. 123, 073003 – Published 16 August 2019 What?: The team lead by Florian Meinert has devised the world’s smallest particle collider to measure detailed aspects of the quantum scattering between a single electron and a neutral atom using a giant Rydberg state. Who?: IQST Young Researcher Florian Meinert from 5th Institute of Physics @UniStuttgart    Read more
Title, Journal: Anisotropic Superfluid Behavior of a Dipolar Bose-Einstein Condensate, Phys. Rev. Lett. 121, 030401 (2018), What?:  Transport measurements on a dipolar superfluid using a Bose-Einstein condensate of 162Dy with strong magnetic dipole-dipole interactions. By moving an attractive laser beam through the condensate the authors observe an anisotropy in superfluid flow. The observations are in excellent agreement with simulations based on the Gross-Pitaevskii equation and highlight the effect of dipolar interactions on macroscopic transport properties, rendering dissipation anisotropic.  Who?: IQST Postdoctoral Fellow Tim Langen Read more
Title, Journal: Ionic Impurity in a Bose-Einstein Condensate at Submicrokelvin Temperatures", Phys. Rev. Lett. 120, 193401 (2018), What?: A giant Rydberg atom enveloping thousands of ordinary atoms could be used to study ion-atom interactions at ultralow temperatures. To suppress the typically dominant electron-neutral interaction, Rydberg states with a principal quantum number up to n=190 are excited from a dense and tightly trapped micron-sized condensate. The results may open up ways to enter the quantum regime of ion-atom scattering for the exploration of charged quantum impurities and associated polaron physics, Who?: IQST Fellow Tilman Pfau Read more
Title, Journal: State-to-state chemistry for three-body recombination in an ultracold rubidium gas, Science Nov 2017, What?: A collaboration between German and American scientists successfully resolved elemental steps in the formation of molecules in one of the simplest chemical reactions, the three-body recombination. For the first time, the scientists are able to quantitatively determine the quantum state distribution of the final products immediately after the three-particle collision in an ultracold gas, Who?:  IQST Fellow Johannes Hecker Denschlag Read more
Title, Journal: Polarization-entangled photons from an InGaAs-based quantum dot emitting in the telecom C-band, Applied Physics Letters Sep 2017, What?: A new nanoscale technique that uses semiconductor quantum dots to bend photons to the wavelengths used by today’s popular C-band standards. “We have demonstrated the emission of polarization-entangled photons from a quantum dot at 1550 nanometers for the first time ever,” said Simone Luca Portalupi, Who?:  IQST YR S. Portalupi,  IQST Fellow P. Michler Read more
Title, Journal: Quantum-Dot Single-Photon Sources for Entanglement Enhanced Interferometry, Physical Review Letters, What?: The authors demonstrate superresolving phase measurements based on two-photon N00N states generated by quantum dot single-photon sources making use of the Hong-Ou-Mandel effect on a beam splitter. A quantum enhanced improvement of the precision in phase uncertainty is achieved which is higher than prescribed by the standard quantum limit. Who?:  IQST Fellow P. Michler Read more
Title, Journal: Nanoscale nuclear magnetic resonance with chemical resolution, Science, What?:  The authors achieve chemical shift resolution in 1H and 19F NMR spectroscopy with a 20 zeptoliter sample volume, by combining the use of a quantum memory and high magnetic fields with a dedicated quantum sensor based on nitrogen vacancy centers in diamond.  Who?: IQST GS M. Pfender, IQST PI P. Neumann, IQST Fellows J. Wrachtrup  Read more
Title, Journal: Submillihertz magnetic spectroscopy performed with a nanoscale quantum sensor, Science, What?:  A quantum spectroscopic technique, coined Qdyne, is introduced in which the spectral resolution is independent of the sensor coherence time (T2) and an enhanced precision scaling of T–3/2 is obtained. By applying Qdyne to shallow NV centers in diamond, we achieved an increase in frequency precision and resolution by nine and eight orders of magnitude, respectively, over the dynamic decoupling technique.  Who?: IQST GS Ilai Schwartz, IQST YR B. Naydenov, IQST PI L. McGuinness, IQST Fellows M. Plenio, F. Jelezko Read more
Title, Journal: Higgs mode and its decay in a two-dimensional antiferromagnet, Nature Physics, What?: Neutron scattering experiments on a two-dimensional antiferromagnet revealed a well-defined, dispersive "Higgs" mode that modulates the amplitude of the ordered moment and decays into transverse spin waves at a rate that depends strongly on the excitation momentum, Who?: IQST Fellow B. Keimer  Read more
Title, Journal: Scalable Quantum Photonics with Single Color Centers in Silicon Carbide, Nano Letters, What?: A scalable array of nanopillars incorporating single silicon vacancy centers in 4H-SiC is developed, which can be readily interfaced with free-space objectives and lensed-fibers , Who?: IQST Fellow J. Wrachtrup Read more
Title, Journal: Measuring broadband magnetic fields on the nanoscale using a hybrid quantum register, Nature Nanotechnology, What?: The magnetic field generated by a hard-disk-drive write head is measured with high spatial resolution and large bandwidth by coherent control of single electron and nuclear spins, Who?: IQST PIs P. Neumann, D. Dasari, IQST Fellow J. Wrachtrup  Read more
Title, Journal: Tracking the coherent generation of polaron pairs in conjugated polymers, Nature Communications, What?: Ultrafast two-dimensional electronic spectroscopy reveals that coherent vibronic coupling induces ultrafast polaron pair formation, accelerates the charge separation dynamics and makes it insensitive to disorder. These findings open up new perspectives for tailoring light-to-current conversion in organic materials. Who?: IQST Fellow S.F. Huelga, M.B. Plenio Read more
Title, Journal: Simultaneous Faraday filtering of the Mollow triplet sidebands with the Cs-D1 clock transition, Nature Communications, What?: A tailored Faraday anomalous dispersion optical filter is presented, which can be used as a key component for the successful link between QD photons and atoms in a hybrid quantum system, Who?: IQST YR S. Portalupi, IQST PIs I. Gerhardt, M. Jetter, IQST Fellows P. Michler, J. Wrachtrup  Read more
Title, Journal: Atom-Chip Fountain Gravimeter, Physical Review Letters, What?: A high-contrast BEC interferometer, realized in a volume as little as a one centimeter cube, paves the way for measurements with sub-μ Gal accuracies in miniaturized, robust devices , Who?: IQST Fellows W. Schleich Read more