A5076701635- Cold Atom Physics and Bose-Einstein Condensates
- Mitochondrial Function and Pathology
- Atomic and Subatomic Physics Research
- Advanced Frequency and Time Standards
- Quantum Information and Cryptography
- Quantum optics and atomic interactions
- Photosynthetic Processes and Mechanisms
- Bacterial Genetics and Biotechnology
- ATP Synthase and ATPases Research
- Quantum Mechanics and Applications
- Electronic and Structural Properties of Oxides
- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Catalytic Processes in Materials Science
- thermodynamics and calorimetric analyses
- Ferroelectric and Piezoelectric Materials
- Quantum and electron transport phenomena
- Metabolism and Genetic Disorders
- Magnetism in coordination complexes
- Quantum Computing Algorithms and Architecture
- Semiconductor materials and devices
- Dark Matter and Cosmic Phenomena
- Heart Rate Variability and Autonomic Control
- Escherichia coli research studies
- Photoreceptor and optogenetics research
Leibniz University Hannover
2016-2022
Max Planck Institute for Gravitational Physics
2018-2021
Ludwig-Maximilians-Universität München
2010-2020
University of Freiburg
2010-2019
Using angle-resolved photoemission spectroscopy, we show that the recently-discovered surface state on SrTiO$_{3}$ consists of non-degenerate $t_{2g}$ states with different dimensional characters. While $d_{xy}$ bands have quasi-2D dispersions weak $k_{z}$ dependence, lifted $d_{xz}$/$d_{yz}$ 3D differ significantly from bulk expectations and signal electrons associated those orbitals permeate near-surface region. Like their more 2D counterparts, size character Fermi components are...
We discuss quantum variational optimization of Ramsey interferometry with ensembles N entangled atoms, and its application to atomic clocks based on a Bayesian approach phase estimation. identify best input states generalized measurements within approximation for the corresponding entangling decoding circuits. These circuits are built from basic operations available particular sensor platform, such as one-axis twisting, or finite range interactions. Optimization is defined relative cost...
Microwave trapped-ion quantum logic gates avoid spontaneous emission as a fundamental source of decoherence. However, microwave two-qubit are still slower than laser-induced and hence more sensitive to fluctuations noise the motional mode frequency. We propose implement amplitude-shaped gate drives obtain resilience such frequency changes without increasing pulse energy per operation. demonstrate by injection during entangling with $^9$Be$^+$ ion qubits. In absence injected noise, amplitude...
We have investigated the benefits of spin squeezed states for clocks operated with typical Brownian frequency noise-limited laser sources. Based on an analytic model closed servo-loop optical atomic clock, we can give quantitative predictions optimal clock stability a given dead time and noise. Our are in very good agreement numerical simulations servo-loop. find that usual cyclic Ramsey interrogation single ensembles time, even current most stable lasers squeezing only improve below...
The NADH:ubiquinone oxidoreductase, respiratory complex I, couples the transfer of electrons from NADH to ubiquinone with a translocation protons across membrane. consists peripheral arm catalyzing electron reaction and membrane involved in proton translocation. recently published X-ray structures revealed presence unique 110 Å "horizontal" helix aligning arm. On basis this finding, it was proposed that energy released by redox is transmitted via conformational change horizontal helix....
Abstract Respiratory complex I plays a central role in cellular energy metabolism coupling NADH oxidation to proton translocation. In humans its dysfunction is associated with degenerative diseases. Here we report the structure of electron input part Aquifex aeolicus at up 1.8 Å resolution bound substrates reduced and oxidized states. The redox states differ by flip peptide bond close binding site. orientation this determined reduction state nearby [Fe-S] cluster N1a. Fixation site-directed...
Non-vanishing fluctuations of the vacuum state are a salient feature quantum theory. These fundamentally limit precision sensors. Nowadays, several systems such as optical clocks, gravitational wave detectors, matter-wave interferometers, magnetometers, and optomechanical approach measurement sensitivities where effect sets fundamental limit, so-called standard (SQL). It has been proposed that SQL can be overcome by squeezing fluctuations. Realizations this scheme have demonstrated in...
We demonstrate the experimental realization of a two-qubit M{\o}lmer-S{\o}rensen gate on magnetic field-insensitive hyperfine transition in $^9$Be$^+$ ions using microwave-near fields emitted by single microwave conductor embedded surface-electrode ion trap. The design was optimized to produce high oscillating field gradient at position. measured fidelity is determined be $98.2\pm1.2\,\%$ and limited technical imperfections, as confirmed comprehensive numerical error analysis. can...
Optical clocks based on ensembles of trapped ions promise record frequency accuracy with good short-term stability. Most suitable ion species lack closed transitions, so the clock signal must be read out indirectly by transferring quantum state to cotrapped logic a different species. Existing methods readout require linear overhead in either time or number ions. Here we describe algorithmic whose scales logarithmically both these respects. The scheme allows nondemolition excited using single...
The energy-converting NADH:ubiquinone oxidoreductase, respiratory complex I, couples NADH oxidation and quinone reduction with the translocation of protons across membrane. Complex I exhibits a unique L shape peripheral arm extending in aqueous phase membrane embedded lipid bilayer. Both arms have length ∼180 Å. electron transfer reaction is catalyzed by series cofactors arm, while catalyzes proton translocation. We used inhibition zinc to shed light on coupling two processes, which not yet...
We consider a large class of Ramsey interferometry protocols which are enhanced by squeezing and un-squeezing operations before after phase signal is imprinted on the collective spin <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>N</mml:mi></mml:math> particles. report an analytical optimization for any given particle number strengths (un-)squeezing. These results can be applied even when experimentally relevant decoherence processes during interactions included. Noise...
Abstract Cosmological observations as well theoretical approaches to physics beyond the standard model provide strong motivations for experimental tests of fundamental symmetries, such CPT invariance. In this context, availability cold baryonic antimatter at CERN has opened an avenue ultrahigh-precision comparisons protons and antiprotons in Penning traps. This work discusses method inspired by quantum logic techniques that will improve particle localization readout speed experiments. The...
The respiratory complex I couples the electron transfer from NADH to ubiquinone with a translocation of protons across membrane. Its nucleotide-binding site is made up unique Rossmann fold accommodate binding substrate and primary acceptor flavin mononucleotide. Binding includes interactions hydroxyl groups adenosine ribose conserved glutamic acid residue. Structural analysis revealed that due steric hindrance electrostatic repulsion, this residue most likely prevents NADPH, which poor...
Respiratory complex I couples the electron transfer exclusively from NADH to a quinone with translocation of protons across membrane. However, Escherichia coli adapts imposed high cellular NADPH concentrations by selecting mutations E183A(F) and E183G(F) that lead catalytic efficiency NADPH. Other at position E183(F) resulting in an efficient oxidation were not selected. Here we show naturally occurring variants exhibit remarkably low level production reactive oxygen species, byproduct...
Static magnetic field gradients superimposed on the electromagnetic trapping potential of a Penning trap can be used to implement laser-less spin-motion couplings that allow realization elementary quantum logic operations in radio-frequency regime. An important scenario practical interest is application $g$-factor measurements with single (anti-)protons test fundamental charge, parity, time reversal (CPT) invariance as pursued BASE collaboration [Smorra et al., Eur. Phys. J. Spec. Top. 224,...
We present Car–Parrinello molecular dynamics simulations of insoluble Prussian blue. This substance represents a metal–organic framework with the cages being filled water molecules. The stability electronic states different multiplicities and relevant Kohn–Sham orbitals are analyzed. structure molecules corresponds essentially to that liquid. In contrast, enclosed is close behavior ice due influence nanosized cage.
In photon recoil spectroscopy, signals are extracted from recoils imparted by the spectroscopy light on motion of trapped ions as demonstrated C. Hempel et al., Nature Photonics 7, 630 (2013) and Y. Wan Communications 5, 3096 (2014). The method exploits exquisite efficiency in detection phonons achievable ion crystals, is thus particularly suitable for species with broad non-cycling transitions where fluorescence photons impractical. Here, we develop a theoretical model description based...
We present Car-Parrinello molecular dynamics simulations of the initial reaction steps leading to an inert oxide layer on aluminium. The mechanism aluminium surface with single oxygen molecules is analysed. After adsorption at dissociate a femtosecond timescale and atoms are chemisorbed distance several angstrom. When exposed higher pressure, essentially consisting threefold coordinated starts form.