Dieter Suter

Technische Universität Dortmund, Dortmund, North Rhine-Westphalia, Germany

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Publications (219)699.18 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: The impact and the development of aneurysms depend to a significant degree on the exchange of liquid between the regular vessel and the pathological extension. A better understanding of this process will lead to improved prediction capabilities. The aim of the current study was to investigate fluid-exchange in aneurysm models of different complexities by combining microscopic magnetic resonance measurements with numerical simulations. In order to evaluate the accuracy and applicability of these methods, the fluid-exchange process between the unaltered vessel lumen and the aneurysm phantoms was analyzed quantitatively using high spatial resolution.
    Medical Physics 10/2015; 42(10):5661-5670. DOI:10.1118/1.4929758 · 2.64 Impact Factor
  • Gonzalo Agustin Alvarez · Dieter Suter · Robin Kaiser ·
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    ABSTRACT: Nonequilibrium dynamics of many-body systems are important in many scientific fields. Here, we report the experimental observation of a phase transition of the quantum coherent dynamics of a three-dimensional many-spin system with dipolar interactions. Using nuclear magnetic resonance (NMR) on a solid-state system of spins at room-temperature, we quench the interaction Hamiltonian to drive the evolution of the system. Depending on the quench strength, we then observe either localized or extended dynamics of the system coherence. We extract the critical exponents for the localized cluster size of correlated spins and diffusion coefficient around the phase transition separating the localized from the delocalized dynamical regime. These results show that NMR techniques are well suited to studying the nonequilibrium dynamics of complex many-body systems.
    Science 08/2015; 349(6250):846. DOI:10.1126/science.1261160 · 33.61 Impact Factor
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    ABSTRACT: The implementation of quantum gates with fidelities that exceed the threshold for reliable quantum computing requires robust gates whose performance is not limited by the precision of the available control fields. The performance of these gates also should not be affected by the noisy environment of the quantum register. Here we use randomized benchmarking of quantum gate operations to compare the performance of different families of gates that compensate errors in the control field amplitudes and decouple the system from the environmental noise. We obtain average fidelities of up to 99.8\%, which exceeds the threshold value for some quantum error correction schemes as well as the expected limit from the dephasing induced by the environment.
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    Jingfu Zhang · Dieter Suter ·
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    ABSTRACT: Hybrid systems consisting of different types of qubits are promising for building quantum computers if they combine useful properties of their constituent qubits. However, they also pose additional challenges if one type of qubits is more susceptible to environmental noise than the others. Dynamical decoupling can help to protect such systems by reducing the decoherence due to the environmental noise, but the protection must be designed such that it does not interfere with the control fields driving the logical operations. Here, we test such a protection scheme on a quantum register consisting of the electronic and nuclear spins of a nitrogen-vacancy center in diamond. The results show that processing is compatible with protection: The dephasing time was extended almost to the limit given by the longitudinal relaxation time of the electron spin.
    Physical Review Letters 04/2015; 115(11). DOI:10.1103/PhysRevLett.115.110502 · 7.51 Impact Factor
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    ABSTRACT: Selective detection of lactate signals in in vivo MR spectroscopy with spectral editing techniques is necessary in situations where strong lipid or signals from other molecules overlap the desired lactate resonance in the spectrum. Several pulse sequences have been proposed for this task. The double-quantum filter SSel-MQC provides very good lipid and water signal suppression in a single scan. As a major drawback, it suffers from significant signal loss due to incomplete refocussing in situations where long evolution periods are required. Here we present a refocused version of the SSel-MQC technique that uses only one additional refocussing pulse and regains the full refocused lactate signal at the end of the sequence. Copyright © 2015 Elsevier Inc. All rights reserved.
    Journal of Magnetic Resonance 03/2015; 255. DOI:10.1016/j.jmr.2015.03.004 · 2.51 Impact Factor
  • Ryszard Narkowicz · Dieter Suter ·
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    ABSTRACT: Planar microresonators provide a large boost of sensitivity for small samples. They can be manufactured lithographically to a wide range of target parameters. The coupler between the resonator and the microwave feedline can be integrated into this design. To optimize the coupling and to compensate manufacturing tolerances, it is sometimes desirable to have a tuning element available that can be adjusted when the resonator is connected to the spectrometer. This paper presents a simple design that allows one to bring undercoupled resonators into the condition for critical coupling. In addition, it also reduces radiation losses and thereby increases the quality factor and the sensitivity of the resonator.
    Review of Scientific Instruments 02/2015; 86(2):024701. DOI:10.1063/1.4906898 · 1.61 Impact Factor
  • Daniel Edelhoff · Stefan Henning · Dieter Suter ·
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    ABSTRACT: Microencapsulation and Microspheres for Food Applications is a solid reflection on the latest developments, challenges, and opportunities in this highly expanding field. This reference examines the various types of microspheres and microcapsules essential to those who need to develop stable and impermeable products at high acidic conditions. It’s also important for the novel design of slow releasing active compound capsules. Each chapter provides an in-depth account of controlled release technologies, evidence based abstracts, descriptions of chemical and physical principals, and key relevant facts relating to food applications. Written in an accessible manner, the book is a must have resource for scientists, researchers, and engineers. Discusses the most current encapsulation technology applied in the food industry, including radiography, computed tomography, magnetic resonance imaging, and dynamic NMR microscopy Presents the use of microsphere immunoassay for mycotoxins detection Covers a broad range of applications of microcapsules and microspheres, including food shelf-life, pesticides for crop protection, and nanoencapsulated bacteriophage for food safety
    Microencapsulation and Microspheres for Food Applications, 1 edited by Leonard M.C. Sagis, 01/2015: chapter 9: pages 173–193; Elsevier., ISBN: 978-0-12-800350-3
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    ABSTRACT: A set of stabilizer operations augmented by some special initial states known as 'magic states', gives the possibility of universal fault-tolerant quantum computation. However, magic state preparation inevitably involves nonideal operations that introduce noise. The most common method to eliminate the noise is magic state distillation (MSD) by stabilizer operations. Here we propose a hybrid MSD protocol by connecting a four-qubit H-type MSD with a five-qubit T-type MSD, in order to overcome some disadvantages of the previous MSD protocols. The hybrid MSD protocol further integrates distillable ranges of different existing MSD protocols and extends the T-type distillable range to the stabilizer octahedron edges. And it provides considerable improvement in qubit cost for almost all of the distillable range. Moreover, we experimentally demonstrate the four-qubit H-type MSD protocol using nuclear magnetic resonance technology, together with the previous five-qubit MSD experiment, to show the feasibility of the hybrid MSD protocol.
    Physical Review A 12/2014; 91(2). DOI:10.1103/PhysRevA.91.022314 · 2.81 Impact Factor
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    Gonzalo A. Alvarez · Dieter Suter · Robin Kaiser ·
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    ABSTRACT: Non-equilibrium dynamics of many-body systems is important in many branches of science, such as condensed matter, quantum chemistry, and ultracold atoms. Here we report the experimental observation of a phase transition of the quantum coherent dynamics of a 3D many-spin system with dipolar interactions, and determine its critical exponents. Using nuclear magnetic resonance (NMR) on a solid-state system of spins at room-temperature, we quench the interaction Hamiltonian to drive the evolution of the system. The resulting dynamics of the system coherence can be localized or extended, depending on the quench strength. Applying a finite-time scaling analysis to the observed time-evolution of the number of correlated spins, we extract the critical exponents v = s = 0.42 around the phase transition separating a localized from a delocalized dynamical regime. These results show clearly that such nuclear-spin based quantum simulations can effectively model the non-equilibrium dynamics of complex many-body systems, such as 3D spin-networks with dipolar interactions.
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    ABSTRACT: Optically-pumped (69)Ga NMR (OPNMR) and optically-detected measurements of polarized photoluminescence (Hanle curves) show a characteristic feature at the light hole-to-conduction band transition in a GaAs/AlxGa1-xAs multiple quantum well sample. OPNMR data are often depicted as a "profile" of the OPNMR integrated signal intensity plotted versus optical pumping photon energy. What is notable is the inversion of the sign of the measured (69)Ga OPNMR signals when optically pumping this light hole-to-conduction band energy in OPNMR profiles at multiple external magnetic fields (B0=4.7T and 3T) for both σ(+) and σ(-) irradiation. Measurements of Hanle curves at B0=0.5T of the same sample exhibit similar phase inversion behavior of the Hanle curves at the photon energy for light hole excitation. The zero-field value of the light-hole state in the quantum well can be predicted for the quantum well structure using the positions of each of these signal-inversion features, and the spin splitting term in the equation for the transition energy yields consistent values at 3 magnetic fields for the excitonic g-factor (g(ex)). This study demonstrates the application of OPNMR and optical measurements of the photoluminescence to detect the light hole transition in semiconductors.
    Journal of Magnetic Resonance 09/2014; 246. DOI:10.1016/j.jmr.2014.07.001 · 2.51 Impact Factor
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    Xinhua Peng · Zhihuang Luo · Supeng Kou · Dieter Suter · Jiangfeng Du ·
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    ABSTRACT: Topological orders are exotic phases of matter existing in strongly correlated quantum systems, which are beyond the usual symmetry description and cannot be distinguished by local order parameters. Here we report an experimental quantum simulation of the Wen-plaquette spin model with different topological orders in a nuclear magnetic resonance system, and observe the adiabatic transition between two $Z_2$ topological orders through a spin-polarized phase by measuring the nonlocal closed-string (Wilson loop) operator. Moreover, we also measure the entanglement properties of the topological orders. This work confirms the adiabatic method for preparing topologically ordered states and provides an experimental tool for further studies of complex quantum systems.
    Physical Review Letters 08/2014; 113(8). DOI:10.1103/PhysRevLett.113.080404 · 7.51 Impact Factor
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    ABSTRACT: We show how to construct an arbitrary robust one-qubit unitary operation with a control Hamiltonian of ${A}_{x}(t){$\sigma${}}_{x}+{A}_{y}(t){$\sigma${}}_{y}$, where ${$\sigma${}}_{i}$ is a Pauli matrix and ${A}_{i}(t)$ is piecewise constant. Our method, based on planar geometry, admits a simple and intuitive interpretation. Furthermore, the total execution time and the number of elementary gates of the obtained sequence are comparable to those of the shortest known concatenated composite pulses.
    Physical Review A 08/2014; 90(5). DOI:10.1103/PhysRevA.90.052330 · 2.81 Impact Factor
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    ABSTRACT: We demonstrate how planar microresonators (PMRs) can be utilized to investigate the angular dependent magnetic resonance response of single magnetic nanostructures. In contrast to alternative detection schemes like electrical or optical detection, the PMR approach provides a classical means of investigating the high frequency dynamics of single magnetic entities, enabling the use of well-established analysis methods of ferromagnetic resonance (FMR) spectroscopy. To demonstrate the performance of the PMR-based FMR setup for angular dependent measurements, we investigate the microwave excited magnons in a single Co stripe of 5 × 1 × 0.02 μm3 and compare the results to micromagnetic simulations. The evolution of excited magnons under rotation of one individual stripe with respect to a static magnetic field is investigated. Besides quasi uniform excitations, we observe magneto-static as well as localized excitations. We find a strong influence of inhomogeneous dynamic and static demagnetizing fields for all modes.
    Journal of Applied Physics 07/2014; 116(3):033913-033913-6. DOI:10.1063/1.4890515 · 2.18 Impact Factor
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    Jingfu Zhang · Daniel Burgarth · Raymond Laflamme · Dieter Suter ·
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    ABSTRACT: Universal quantum computation requires the implementation of arbitrary control operations on the quantum register. In most cases, this is achieved by external control fields acting selectively on each qubit to drive single-qubit operations. In combination with a drift Hamiltonian containing interactions between the qubits, this allows the implementation of any required gate operation. Here, we demonstrate an alternative scheme that does not require local control for all qubits: we implement one- and two-qubit gate operations on a set of target qubits indirectly, through a combination of gates on directly controlled actuator qubits with a drift Hamiltonian that couples actuator and target qubits. Experiments are performed on nuclear spins, using radio-frequency pulses as gate operations and magnetic-dipole couplings for the drift Hamiltonian.
    Physical Review A 05/2014; 91(1). DOI:10.1103/PhysRevA.91.012330 · 2.81 Impact Factor
  • Mirjam Holbach · Jörg Lambert · Dieter Suter ·
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    ABSTRACT: The selective excitation of metabolite signals in vivo requires the use of specially adapted pulse techniques, in particular when the signals are weak and the resonances overlap with those of unwanted molecules. Several pulse sequences have been proposed for this spectral editing task. However, their performance is strongly degraded by unavoidable experimental imperfections. Here, we show that optimal control theory can be used to generate pulses and sequences that perform almost ideally over a range of rf field strengths and frequency offsets that can be chosen according to the specifics of the spectrometer or scanner being used. We demonstrate this scheme by applying it to lactate editing. In addition to the robust excitation, we also have designed the pulses to minimize the signal of unwanted molecular species.
    Journal of Magnetic Resonance 03/2014; 243C:8-16. DOI:10.1016/j.jmr.2014.03.007 · 2.51 Impact Factor
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    ABSTRACT: Implementing precise operations on quantum systems is one of the biggest challenges for building quantum devices in a noisy environment. Dynamical decoupling (DD) attenuates the destructive effect of the environmental noise, but so far it has been used primarily in the context of quantum memories. Here, we present a general scheme for combining DD with quantum logical gate operations and demonstrate its performance on the example of an electron spin qubit of a single nitrogen-vacancy center in diamond. We achieve process fidelities >98% for gate times that are 2 orders of magnitude longer than the unprotected dephasing time $T_{2}$.
    Physical Review Letters 02/2014; 112(5):050502. DOI:10.1103/PhysRevLett.112.050502 · 7.51 Impact Factor

  • 01/2014; De Gruyter., ISBN: 3110306751
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    Gonzalo A. Alvarez · Robin Kaiser · Dieter Suter ·
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    ABSTRACT: Quantum information processing often uses systems with dipolar interactions. We use a nuclear spin-based quantum simulator, to study the spreading of information in such a dipolar-coupled system and how perturbations to the dipolar couplings limit the spreading, leading to localization. In [Phys. Rev. Lett. 104, 230403 (2010)], we found that the system reaches a dynamic equilibrium size, which decreases with the square of the perturbation strength. Here, we study the impact of a disordered Hamiltonian with dipolar 1/r^3 interactions. We show that the expansion of the coherence length of the cluster size of the spins becomes frozen in the presence of large disorder, reminiscent of Anderson localization of non-interacting waves in a disordered potential.
    Annalen der Physik 11/2013; 525:833. DOI:10.1002/andp.201300096 · 3.05 Impact Factor
  • R Narkowicz · H Ogata · E Reijerse · D Suter ·
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    ABSTRACT: Cryogenic probes have significantly increased the sensitivity of NMR. Here, we present a compact EPR receiver design capable of cryogenic operation. Compared to room temperature operation, it reduces the noise by a factor of ≈2.5. We discuss in detail the design and analyze the resulting noise performance. At low microwave power, the input noise density closely follows the emission of a cooled 50Ω resistor over the whole measurement range from 20K up to room temperature. To minimize the influence of the microwave source noise, we use high microwave efficiency (≈1.1-1.7mTW(-1/2)) planar microresonators. Their efficient conversion of microwave power to magnetic field permits EPR measurements with very low power levels, typically ranging from a few μW down to fractions of nW.
    Journal of Magnetic Resonance 10/2013; 237C:79-84. DOI:10.1016/j.jmr.2013.09.017 · 2.51 Impact Factor
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    ABSTRACT: Alterations of the blood flow are associated with various cardiovascular diseases. Precise knowledge of the velocity distribution is therefore important for understanding these diseases and predicting the effect of different medical intervention schemes. The goal of this work is to estimate the precision with which the velocity field can be measured and predicted by studying two simple model geometries with NMR micro imaging and computational fluid dynamics. For these initial experiments, we use water as an ideal test medium. The phantoms consist of tubes simulating a straight blood vessel and a step between two tubes of different diameters, which can be seen as a minimal model of the situation behind a stenosis. For both models, we compare the experimental data with the numerical prediction, using the experimental boundary conditions. For the simpler model, we also compare the data to the analytical solution. As an additional validation, we determine the divergence of the velocity field and verify that it vanishes within the experimental uncertainties. We discuss the resulting precision of the simulation and the outlook for extending this approach to the analysis of specific cases of arteriovascular problems.
    Journal of Magnetic Resonance 07/2013; 235C:42-49. DOI:10.1016/j.jmr.2013.07.002 · 2.51 Impact Factor

Publication Stats

4k Citations
699.18 Total Impact Points


  • 1995-2015
    • Technische Universität Dortmund
      • • Chair of Experimental Physics II
      • • Faculty of Physics
      • • High Frequency Institute
      Dortmund, North Rhine-Westphalia, Germany
  • 2010
    • Massachusetts Institute of Technology
      Cambridge, Massachusetts, United States
  • 1987-1989
    • University of California, Berkeley
      • • Lawrence Berkeley Laboratory
      • • Department of Chemistry
      Berkeley, California, United States
  • 1986
    • CSU Mentor
      • Department of Chemistry
      Long Beach, California, United States
  • 1982
    • Hochschule für Technik Zürich
      Zürich, Zurich, Switzerland