Steffen J. Glaser

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Relaxation effects impose fundamental limitations on our ability to coherently control quantum mechanical phenomena. In this article, we use principles of optimal control theory to establish physical limits on how closely a quantum mechanical system can be steered to a desired target state in the presence of relaxation. In particular, we explicitly compute(More)
In this paper we provide an explicit construction of any arbitrary unitary transformation on n qubits from one qubit and a single two qubit quantum gate. Building on the previous work demonstrating the universality of two qubit quantum gates, we present here an explicit implementation. The construction is based on the Cartan decomposition of the semi-simple(More)
Metabolic imaging with hyperpolarized [1-(13)C]pyruvate offers the unique opportunity for a minimally invasive detection of cellular metabolism. Efficient and robust acquisition and reconstruction techniques are required for capturing the wealth of information present for the limited duration of the hyperpolarized state (~1 min). In this study, the(More)
Radio-frequency pulses are used in nuclear-magnetic-resonance spectroscopy to produce unitary transfer of states. Pulse sequences that accomplish a desired transfer should be as short as possible in order to minimize the effects of relaxation, and to optimize the sensitivity of the experiments. Many coherence-transfer experiments in NMR, involving a network(More)
Within the last decade hyperpolarized [1-13C] pyruvate chemical-shift imaging has demonstrated impressive potential for metabolic MR imaging for a wide range of applications in oncology, cardiology, and neurology. In this work, a highly efficient pulse sequence is described for time-resolved, multislice chemical shift imaging of the injected substrate and(More)
Experiments in coherent spectroscopy correspond to control of quantum mechanical ensembles guiding them from initial to final target states. The control inputs (pulse sequences) that accomplish these transformations should be designed to minimize the effects of relaxation and to optimize the sensitivity of the experiments. For example in nuclear magnetic(More)
This paper shows how C-numerical-range related new strucures may arise from practical problems in quantum control—and vice versa, how an understanding of these structures helps to tackle hot topics in quantum information. We start out with an overview on the role of C-numerical ranges in current research problems in quantum theory: the quantum mechanical(More)
In this paper, we develop methods for optimal manipulation of coupled spin dynamics in the presence of relaxation. These methods are used to compute analytical bounds for the optimal efficiency of coherence transfer between coupled nuclear spins in presence of longitudinal and transverse relaxation. We derive relaxation optimized pulse sequences which(More)
Quantum control plays a key role in quantum technology, e.g. for steering quantum hardware systems, spectrometers or supercon-ducting solid-state devices. In terms of computation, quantum systems provide a unique potential for coherent parallelisation that may exponentially speed up algorithms as in Shor's prime factorisation. Translating quantum software(More)