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Quantum control theory and applications: A survey
 IET Control Theory & Applications
, 2010
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The Magnus expansion and some of its applications
, 2008
"... Approximate resolution of linear systems of differential equations with varying coefficients is a recurrent problem shared by a number of scientific and engineering areas, ranging from Quantum Mechanics to Control Theory. When formulated in operator or matrix form, the Magnus expansion furnishes an ..."
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Approximate resolution of linear systems of differential equations with varying coefficients is a recurrent problem shared by a number of scientific and engineering areas, ranging from Quantum Mechanics to Control Theory. When formulated in operator or matrix form, the Magnus expansion furnishes an elegant setting to built up approximate exponential representations of the solution of the system. It provides a power series expansion for the corresponding exponent and is sometimes referred to as TimeDependent Exponential Perturbation Theory. Every Magnus approximant corresponds in Perturbation Theory to a partial resummation of infinite terms with the important additional property of preserving at any order certain symmetries of the exact solution. The goal of this review is threefold. First, to collect a number of developments scattered through half a century of scientific literature on Magnus expansion. They concern the methods for the generation of terms in the expansion, estimates of the radius of convergence of the series, generalizations and related nonperturbative
Exploring the physical limits of saturation contrast in Magnetic Resonance Imaging Sci
 Rep
, 2012
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High Fidelity Quantum Information Processing with Trapped Ions
, 2006
"... The final copy of this thesis has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above mentioned discipline. ..."
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The final copy of this thesis has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above mentioned discipline.
Ultracold molecules: vehicles to scalable quantum information processing
 New Journal of Physics
, 2009
"... Abstract. We describe a novel scheme to implement scalable quantum information processing using LiCs molecular state to entangle 6 Li and 133 Cs ultracold atoms held in independent optical lattices. The 6 Li atoms will act as quantum bits to store information, and 133 Cs atoms will serve as messeng ..."
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Abstract. We describe a novel scheme to implement scalable quantum information processing using LiCs molecular state to entangle 6 Li and 133 Cs ultracold atoms held in independent optical lattices. The 6 Li atoms will act as quantum bits to store information, and 133 Cs atoms will serve as messenger bits that aid in quantum gate operations and mediate entanglement between distant qubit atoms. Each atomic species is held in a separate optical lattice and the atoms can be overlapped by translating the lattices with respect to each other. When the messenger and qubit atoms are overlapped, targeted single spin operations and entangling operations can be performed by coupling the atomic states to a molecular state with radiofrequency pulses. By controlling the frequency and duration of the radiofrequency pulses, entanglement can either be created or swapped between a qubit messenger pair. We estimate operation fidelities for entangling two distant qubits and discuss scalability of this scheme and constraints on the optical lattice lasers. PACS numbers: 67.85.d, 3.67Lx, 37.10JkUltracold molecules: vehicles to scalable quantum information processing 2 1.
Engineered open systems and quantum simulations with atoms and ions
 Advances In Atomic, Molecular, and Optical Physics
, 2012
"... The enormous experimental progress in atomic, molecular and optical (AMO) physics during the last decades allows us nowadays to isolate single, a few or even manybody ensembles of microscopic particles, and to manipulate their quantum properties at a level of precision, which still seemed unthin ..."
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The enormous experimental progress in atomic, molecular and optical (AMO) physics during the last decades allows us nowadays to isolate single, a few or even manybody ensembles of microscopic particles, and to manipulate their quantum properties at a level of precision, which still seemed unthinkable some years ago. This versatile set of tools has enabled the development of the wellestablished concept of engineering of manybody Hamiltonians in various physical platforms. These available tools, however, can also be harnessed to extend the scenario of Hamiltonian engineering to a more general Liouvillian setting, which in addition to coherent dynamics also includes controlled dissipation in manybody quantum systems. Here, we review recent theoretical and experimental progress in different directions along these lines, with a particular focus on physical realizations with systems
Sensitive magnetic control of ensemble nuclear spin hyperpolarization in diamond
"... Dynamic nuclear polarization, which transfers the spin polarization of electrons to nuclei, is routinely applied to enhance the sensitivity of nuclear magnetic resonance. This method is particularly useful when spin hyperpolarization can be produced and controlled optically or electrically. Here we ..."
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Dynamic nuclear polarization, which transfers the spin polarization of electrons to nuclei, is routinely applied to enhance the sensitivity of nuclear magnetic resonance. This method is particularly useful when spin hyperpolarization can be produced and controlled optically or electrically. Here we show complete polarization of nuclei located near optically polarized nitrogenvacancy centres in diamond. Close to the groundstate level anticrossing condition of the nitrogenvacancy electron spins, 13C nuclei in the first shell are polarized in a pattern that depends sensitively upon the magnetic field. Based on the anisotropy of the hyperfine coupling and of the optical polarization mechanism, we predict and observe a reversal of the nuclear spin polarization with only a few millitesla change in the magnetic field. This method of magnetic control of high nuclear polarization at room temperature can be applied in sensitivity enhanced nuclear magnetic resonance of bulk nuclei, nuclearbased spintronics, and quantum computation in diamond.
A Constructive Algorithm for Reversible Logic Synthesis
"... Abstract — This paper presents a constructive synthesis algorithm for any nqubit reversible function. Given any nqubit reversible function, there are N distinct input patterns different from their corresponding outputs, where N ≤ 2 n, and the other (2 n − N) input patterns will be the same as their ..."
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Abstract — This paper presents a constructive synthesis algorithm for any nqubit reversible function. Given any nqubit reversible function, there are N distinct input patterns different from their corresponding outputs, where N ≤ 2 n, and the other (2 n − N) input patterns will be the same as their outputs. We show that this circuit can be synthesized by at most 2n · N ‘(n − 1)’CNOT gates and 4n 2 · N NOT gates. The time complexity of our algorithm has asymptotic upper bound O(n · 4 n). The space complexity of our synthesis algorithm is also O(n · 2 n). The computational complexity of our synthesis algorithm is exponentially lower than the complexity of breadthfirst search based synthesis algorithm. I.