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Ultrafast Control of Spin and Motion in Trapped Ions
, 2013
"... Trapped atomic ions are a promising medium for quantum computing, due to their long coherence times and potential for scalability. Current methods of entangling ions rely on addressing individual modes of motion within the trap and applying qubit state dependent forces with external fields. This ap ..."
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Trapped atomic ions are a promising medium for quantum computing, due to their long coherence times and potential for scalability. Current methods of entangling ions rely on addressing individual modes of motion within the trap and applying qubit state dependent forces with external fields. This approach can limit the speed of entangling gates and make them vulnerable to decoherence due to coupling to unwanted modes or ion heating. This thesis is directed towards demonstrating novel entanglement schemes which are not limited by the trap frequency, and can be made almost arbitrarily fast. Towards this goal, I report here on the first experiments using ultrafast laser pulses to control the internal and external states of a single trapped ion. I begin with experiments in ultrafast spin control, showing how a single laser pulse can be used to completely control both spin degrees of freedom of the ion qubit in tens of picoseconds. I also show how a train of weak pulses can be used to drive Raman transitions based on a frequency comb. I then discuss experiments using pulses to rapidly entangle the spin with the motion, and how careful spectral redistribution allows a single pulse to execute a spindependent momentum kick. Finally, I explain how these spindependent momentum kicks can be used in the future to create an ultrafast entangling gate. I go over how such a gate would work, and present experimentally realizable timing sequences which would create a maximally entangled state of two ions in a time faster than the period of motion in the trap.
1 HighLevel Interconnect Model for the Quantum Logic Array Architecture
, 2008
"... We summarize the main characteristics of the quantum logic array (QLA) architecture with a careful look at the key issues not described in the original conference publications: primarily, the teleportationbased logical interconnect. The design goal of the the quantum logic array architecture is to ..."
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We summarize the main characteristics of the quantum logic array (QLA) architecture with a careful look at the key issues not described in the original conference publications: primarily, the teleportationbased logical interconnect. The design goal of the the quantum logic array architecture is to illustrate a model for a largescale quantum architecture that solves the primary challenges of systemlevel reliability and data distribution over large distances. The QLA’s logical interconnect design, which employs the quantum repeater protocol, is in principle capable of supporting the communication requirements for applications as large as the factoring of a 2048bit number using Shor’s quantum factoring algorithm. Our physicallevel assumptions and architectural component validations are based on the trapped ion technology for implementing quantum computing.
4. TITLE AND SUBTITLE Quantum Computing Classical Physics
, 2001
"... AB^SkAR:lR05" The public «porting burden for this collection of information is.estimated to average.^ourper response, including thl gathering and maintaining the data needed, and completing and reviewing the collection of informafröh. Send comments ret ..."
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AB^SkAR:lR05" The public «porting burden for this collection of information is.estimated to average.^ourper response, including thl gathering and maintaining the data needed, and completing and reviewing the collection of informafröh. Send comments ret
Perspectives on SolidState Flying Qubits
"... The quest for quantumcomputing capable architectures has recently focused on solidstate implementations, since they seem more prone to meet the required criteria [1] of scalability and integrability than alternative approaches like the ones based on nuclear magnetic resonance, ion traps or quantum ..."
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The quest for quantumcomputing capable architectures has recently focused on solidstate implementations, since they seem more prone to meet the required criteria [1] of scalability and integrability than alternative approaches like the ones based on nuclear magnetic resonance, ion traps or quantum electrodynamics techniques [2]. In many proposals different components of a quantumcomputing system are dedicated to different quantum transformations. As a consequence at each stage the outputs of these transformations, i.e. the state of a qubit register, must be moved to the inputs of other quantum gates. This process, overlooked in the early times of quantum information processing research, results to
SubDoppler cooling of neutral atoms in a grating magnetooptical trap
, 191601
"... The grating magnetooptical trap (GMOT) requires only one beam and three planar diffraction gratings to form a cloud of cold atoms above the plane of the diffractors. Despite the complicated polarization arrangement, we demonstrate subDoppler cooling of 87 Rb atoms to a temperature of 7.60.6 μK th ..."
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The grating magnetooptical trap (GMOT) requires only one beam and three planar diffraction gratings to form a cloud of cold atoms above the plane of the diffractors. Despite the complicated polarization arrangement, we demonstrate subDoppler cooling of 87 Rb atoms to a temperature of 7.60.6 μK through a multistage, fardetuned GMOT in conjunction with optical molasses. A decomposition of the electric field into polarization components for this geometry does not yield a mapping onto standard subDoppler lasercooling configurations. With numerical simulations, we find that the polarization composition of the GMOT optical field, which includes σ and π polarized light, does produce subDoppler temperatures.
NMR based quantum information processing: . . .
, 2008
"... Nuclear magnetic resonance (NMR) provides an experimental setting to explore physical implementations of quantum information processing (QIP). Here we introduce the basic background for understanding applications of NMR to QIP and explain their current successes, limitations and potential. NMR spect ..."
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Nuclear magnetic resonance (NMR) provides an experimental setting to explore physical implementations of quantum information processing (QIP). Here we introduce the basic background for understanding applications of NMR to QIP and explain their current successes, limitations and potential. NMR spectroscopy is well known for its wealth of diverse coherent manipulations of spin dynamics. Ideas and instrumentation from liquid state NMR spectroscopy have been used to experiment with QIP. This approach has carried the field to a complexity of about 10 qubits, a small number for quantum computation but large enough for observing and better understanding the complexity of the quantum world. While liquid state NMR is the only presentday technology about to reach this number of qubits, further increases in complexity will require new methods. We sketch one direction leading towards a scalable quantum computer using spin 1/2 particles. The next step of which is a solid state NMRbased QIP
On heatbath algorithmic cooling and its . . .
, 2005
"... Preparation of a quantum computer in a known state is essential for quantum computation. This is required in initializing a quantum computer for computation, and in dynamically supplying ancilla qubits to achieve faulttolerance. Heatbath algorithmic cooling is an implementationindependent proce ..."
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Preparation of a quantum computer in a known state is essential for quantum computation. This is required in initializing a quantum computer for computation, and in dynamically supplying ancilla qubits to achieve faulttolerance. Heatbath algorithmic cooling is an implementationindependent procedure, which has been proposed as means to purify the initially mixed state for computation. We present numerical simulations of the heatbath algorithmic cooling procedure, and highlight the theoretical limits on achievable cooling using this algorithm. We also report the implementation of this algorithm on a 3qubit processor as a proof of principle. The experiment is performed using the nuclear magnetic resonance (NMR) of singlecrystal Malonic acid (C3H4O4) in the solid state. Using the algorithm, and starting from the totally mixed state on the computational qubits, we are able to cool one of the qubits below the effective heatbath temperature. iii Acknowledgments Secondly, I am indebted to my parents, Mahmoud and Thoria, for everything, not the least of which is their motivation and moral support in these past years. I must also acknowledge my siblings, Muhammad, Omar, and Asmaa, for they are my inspiration. I must thank the members of my advisory committee; Dr. Raymond Laflamme,
NMR based quantum . . .
, 2002
"... Nuclear magnetic resonance (NMR) provides an experimental setting to explore physical implementations of quantum information processing (QIP). Here we introduce the basic background for understanding applications of NMR to QIP and explain their current successes, limitations and potential. NMR spect ..."
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Nuclear magnetic resonance (NMR) provides an experimental setting to explore physical implementations of quantum information processing (QIP). Here we introduce the basic background for understanding applications of NMR to QIP and explain their current successes, limitations and potential. NMR spectroscopy is well known for its wealth of diverse coherent manipulations of spin dynamics. Ideas and instrumentation from liquid state NMR spectroscopy have been used to experiment with QIP. This approach has carried the field to a complexity of about 10 qubits, a small number for quantum computation but large enough for observing and better understanding the complexity of the quantum world. While liquid state NMR is the only presentday technology about to reach this number of qubits, further increases in complexity will require new methods. We sketch one direction leading towards a scalable quantum computer using spin 1/2 particles. The next step of which is a solid state NMRbased QIP
Algorithmic Quantum Channel Simulation

, 2015
"... Quantum simulation, which is generically the task to employ quantum computers to simulate quantum physical models, has been one of the most significant motivations and applications of quantum computing. Quantum dynamics, unitary or nonunitary Markovian dynamics driven by local interactions, has been ..."
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Quantum simulation, which is generically the task to employ quantum computers to simulate quantum physical models, has been one of the most significant motivations and applications of quantum computing. Quantum dynamics, unitary or nonunitary Markovian dynamics driven by local interactions, has been proved to be efficiently simulatable on quantum computers. Extending the underlying models in quantum computation and quantum simulation from unitary to general nonunitary evolution, and from continuoustime to discretetime evolution is essential not only for quantum simulation of more general processes, e.g., dissipative processes with evident nonMarkovian effects, but also for developing alternative quantum computing models and algorithms. In this thesis, we explore quantum simulation problems mainly from the following three themes. First, we extend quantum simulation framework of Hamiltoniandriven evolution to quantum simulation of quantum channels, combined with the scheme of algorithmic simulation that accepts a promised simulation accuracy, hence algorithmic quantum channel simulation. Our simulation scheme contains a classical preprocessing part, i.e. a classical algorithm for