Download or read book Adiabatic Quantum Computing with Dressed Rydberg Atoms written by and published by . This book was released on 2011 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Robust Quantum Logic in Neutral Atoms Via Adiabatic Rydberg Dressing written by and published by . This book was released on 2015 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: We study a scheme for implementing a controlled-Z (CZ) gate between two neutral-atom qubits based on the Rydberg blockade mechanism in a manner that is robust to errors caused by atomic motion. By employing adiabatic dressing of the ground electronic state, we can protect the gate from decoherence due to random phase errors that typically arise because of atomic thermal motion. In addition, the adiabatic protocol allows for a Doppler-free configuration that involves counterpropagating lasers in a [sigma]+/[sigma]- orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual motional error is dominated by dipole-dipole forces acting on doubly-excited Rydberg atoms when the blockade is imperfect. As a result, for reasonable parameters, with qubits encoded into the clock states of 133Cs, we predict that our protocol could produce a CZ gate in
Download or read book Advances in Atomic Molecular and Optical Physics written by and published by Academic Press. This book was released on 2016-05-31 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Atomic, Molecular, and Optical Physics provides a comprehensive compilation of recent developments in a field that is in a state of rapid growth, as new experimental and theoretical techniques are used on many problems, both old and new. Topics covered include related applied areas, such as atmospheric science, astrophysics, surface physics, and laser physics, with timely articles written by distinguished experts that contain relevant review material and detailed descriptions of important developments in the field. - Presents the work of international experts in the field - Comprehensive articles compile recent developments in a field that is experiencing rapid growth, with new experimental and theoretical techniques emerging - Ideal for users interested in optics, excitons, plasmas, and thermodynamics - Topics covered include atmospheric science, astrophysics, surface physics, and laser physics, amongst others
Download or read book Rydberg Physics in a Cryogenic System for Hybrid Quantum Interfaces written by Juan Camilo Bohorquez (Ph.D.) and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis summarizes the hardware constructed for the Hybrid experiment, as well as the experimental progress made in Hybrid, to enable the construction of a Hybrid quantum system. This systems seeks to couple neutral atoms to high quality factor microwave cavities. Cavity QED systems, such as this one, are an integral part of atom-superconducting hybrid quantum computing. These systems are also promising candidates for transduction of quantum information from the microwave to the optical regime. Such transduction would enable the quantum networking of superconducting (SC) quantum registers at long distances. Rydberg atoms are uniquely suited to such cavity QED systems owing to the strong dipole moments of microwave-frequency Rydberg-Rydberg transitions, and the accessibility of optical transitions. Though the development of such systems is made challenging due to the significant dc polarizability of Rydberg states, and the size of electric field noise near surfaces. This thesis outlines the application of a microwave dressing scheme to a Rydberg system, and a demonstration of the reduction of polarizability said states by a factor of 7. In addition, we summarize modeling and analysis of the dressed-atom system, and how such a dressing scheme can be engineered to fully null the polarizability of a Rydberg state in one direction. We also summarize the limits of the dressing scheme, namely the anisotropy of the polarizability of the dressed Rydberg states, where in one direction the polarizability may be fully nulled, but in normal directions the polarizability is only reduced by 50[percent]. We also demonstrate and discuss the enhanced fourth-order, hyperpolarizability, of the dressed Rydberg states, and how even in relatively weak dc fields (~ 20 mV/cm) these effects can come to dominate the un-dressed polarizability. Through these drawbacks, coupled with a study of the published efforts to understand and mitigate electric field noise from surfaces, we conclude that a dressing scheme alone will be insufficient to enable high-fidelity Rydberg cavity QED demonstrations in our device on its own. Such efforts would require a greater atom-surface distance, as well as the implementation of significant dc surface field noise mitigation and compensation techniques, in conjunction with the dressing scheme proposed, to produce the required fidelity of atom-cavity interactions. This thesis then discusses the first demonstration of Rydberg Rabi excitations via a novel quadrupole-dipole two-photon excitation scheme. This scheme presents a significant reduction in the Doppler-shift induced dephasing in finite temperature atomic systems, due to the significantly reduced k-vector mismatch between the counter-propagating Rydberg fields. This thesis presents an analytical model for understanding the quadrupole excitation dynamics, as well as the two-photon Rabi dynamics of the driven system, in the adiabatic regime. This thesis also uses a tool to solve the master equation to evaluate the validity of the {adiabatic elimination} approximation in our system. We then uses those analytical and numerical tools to engineer the Rydberg laser polarizations, frequencies and powers for improved Rabi flopping fidelity. The analytical treatment is followed up with experimental date, demonstrating the Rydberg Rabi flopping between the ground state and $\ds 52P_{3/2},m_j=1/2$ Rydberg state. We supplement the experimental data, and analysis of it with a detailed accounting of the parameters of the Rydberg laser fields and noise sources which degrade the fidelity of the Rydberg Rabi operations, as measured {in situ}, or calibrated externally. Finally this thesis present a path forward for the Hybrid experiment, considering the challenges presented by surface electric field noise. The upgraded design for the experimental system makes use of a bulk microwave resonator, designed to require much greater atom-surface distances inside the atom-cavity interaction region. This device would enable atom-cavity interactions for cavity frequencies in the 5-7 GHz band, the native operating frequencies of existing SC quantum systems, while allowing the users to mitigate the size and effects of surface electric fields. We discuss the design considerations and current status of the new cavity design, as well as the design of the optical trapping, transport and readout techniques which will be used to localize and control the atoms inside the interaction region.
Download or read book Adiabatic Quantum Computing with Neutral Atoms written by and published by . This book was released on 2012 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Adiabatic Quantum Computation and Quantum Annealing written by Catherine C. McGeoch and published by Morgan & Claypool. This book was released on 2014-07 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adiabatic quantum computation (AQC) is an alternative to the better-known gate model of quantum computation. The two models are polynomially equivalent, but otherwise quite dissimilar: one property that distinguishes AQC from the gate model is its analog nature. Quantum annealing (QA) describes a type of heuristic search algorithm that can be implemented to run in the ``native instruction set'' of an AQC platform. D-Wave Systems Inc. manufactures {quantum annealing processor chips} that exploit quantum properties to realize QA computations in hardware. The chips form the centerpiece of a novel computing platform designed to solve NP-hard optimization problems. Starting with a 16-qubit prototype announced in 2007, the company has launched and sold increasingly larger models: the 128-qubit D-Wave One system was announced in 2010 and the 512-qubit D-Wave Two system arrived on the scene in 2013. A 1,000-qubit model is expected to be available in 2014. This monograph presents an introductory overview of this unusual and rapidly developing approach to computation. We start with a survey of basic principles of quantum computation and what is known about the AQC model and the QA algorithm paradigm. Next we review the D-Wave technology stack and discuss some challenges to building and using quantum computing systems at a commercial scale. The last chapter reviews some experimental efforts to understand the properties and capabilities of these unusual platforms. The discussion throughout is aimed at an audience of computer scientists with little background in quantum computation or in physics.
Download or read book Neutral Atom Adiabatic Quantum Computing written by and published by . This book was released on 2013 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Approximability of Optimization Problems through Adiabatic Quantum Computation written by William Cruz-Santos and published by Springer Nature. This book was released on 2022-05-31 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt: The adiabatic quantum computation (AQC) is based on the adiabatic theorem to approximate solutions of the Schrödinger equation. The design of an AQC algorithm involves the construction of a Hamiltonian that describes the behavior of the quantum system. This Hamiltonian is expressed as a linear interpolation of an initial Hamiltonian whose ground state is easy to compute, and a final Hamiltonian whose ground state corresponds to the solution of a given combinatorial optimization problem. The adiabatic theorem asserts that if the time evolution of a quantum system described by a Hamiltonian is large enough, then the system remains close to its ground state. An AQC algorithm uses the adiabatic theorem to approximate the ground state of the final Hamiltonian that corresponds to the solution of the given optimization problem. In this book, we investigate the computational simulation of AQC algorithms applied to the MAX-SAT problem. A symbolic analysis of the AQC solution is given in order to understand the involved computational complexity of AQC algorithms. This approach can be extended to other combinatorial optimization problems and can be used for the classical simulation of an AQC algorithm where a Hamiltonian problem is constructed. This construction requires the computation of a sparse matrix of dimension 2n × 2n, by means of tensor products, where n is the dimension of the quantum system. Also, a general scheme to design AQC algorithms is proposed, based on a natural correspondence between optimization Boolean variables and quantum bits. Combinatorial graph problems are in correspondence with pseudo-Boolean maps that are reduced in polynomial time to quadratic maps. Finally, the relation among NP-hard problems is investigated, as well as its logical representability, and is applied to the design of AQC algorithms. It is shown that every monadic second-order logic (MSOL) expression has associated pseudo-Boolean maps that can be obtained by expanding the given expression, and also can be reduced to quadratic forms. Table of Contents: Preface / Acknowledgments / Introduction / Approximability of NP-hard Problems / Adiabatic Quantum Computing / Efficient Hamiltonian Construction / AQC for Pseudo-Boolean Optimization / A General Strategy to Solve NP-Hard Problems / Conclusions / Bibliography / Authors' Biographies
Download or read book Quantum Control of Multi Wave Mixing written by Yanpeng Zhang and published by John Wiley & Sons. This book was released on 2013-07-17 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multi-wave mixing gives rise to new frequency components due to the interaction of light signals with a suitable nonlinear medium. In this book a systematic framework for the control of these processes is used to lead readers through a plethora of related effects and techniques.
Download or read book Quantum Engineering by Rydberg Dressing in a Cold Atomic Gas written by Ognjen Marković and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We are witnessing remarkable progress in building large and controllable quantum systems. At the forefront of this development are laser-cooled atoms, which can be used as atomic clocks, sensitive measurement probes or quantum computing platforms. A necessary ingredient of many computation and metrology schemes is the ability to have local and dynamical control of interactions between atoms. In this thesis, I present a platform based on highly excited Rydberg states of cesium atoms. We realize long-range optically controlled Ising interactions in a cloud of cold cesium atoms by coupling the atomic ground state to a Rydberg state. By adding a microwave coupling between the clock states of cesium, we emulate a transverse-field Ising model and detect dynamical signatures of the paramagnetic-ferromagnetic phase transition. I present work on producing spin-squeezed states, in which quantum correlations enable higher measurement precision than possible with an uncorrelated state. I show the first measurement of spin squeezing with the local Ising interactions, demonstrating a factor $\xi^2=\num{0.80(7)}$ reduction in phase variance below the projection noise limit. I present prospects for improving spin squeezing in this system, by minimizing sources of loss, trapping atoms in a regular array and utilizing the transverse field. Finally, I propose an application of optically controlled Ising interactions to the computational problem of number partitioning, where a hardware-efficient encoding in a central spin system enables solutions to be found via Grover's algorithm. The simulated performance of the algorithm exhibits a quantum speedup in a system of Rydberg-dressed atoms, paving the way for demonstrations in near-term experiments.
Download or read book Quantum Information Processing with Rydberg dressed Atoms written by and published by . This book was released on 2013 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Atomic precision Fabrication of Qubits for an Adiabatic Quantum Computer written by and published by . This book was released on 2012 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Adiabatic Processes Noise and Stochastic Algorithms for Quantum Computing and Quantum Simulation written by Guanglei Xu and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rapid developments in experiments provide promising platforms for realising quantum computation and quantum simulation. This, in turn, opens new possibilities for developing useful quantum algorithms and explaining complex many-body physics. The advantages of quantum computation have been demonstrated in a small range of subjects, but the potential applications of quantum algorithms for solving complex classical problems are still under investigation. Deeper understanding of complex many-body systems can lead to realising quantum simulation to study systems which are inaccessible by other means.This thesis studies different topics of quantum computation and quantum simulation.The first one is improving a quantum algorithm in adiabatic quantum computing, which can be used to solve classical problems like combinatorial optimisation problems and simulated annealing. We are able to reach a new bound of time cost for the algorithm which has a potential to achieve a speed up over standard adiabatic quantum computing. The second topic is to understand the amplitude noise in optical lattices in the context of adiabatic state preparation and the thermalisation of the energy introduced to the system. We identify regimes where introducing certain type of noise in experiments would improve the final fidelity of adiabatic state preparation, and demonstrate the robustness of the state preparation to imperfect noise implementations. We also discuss the competition between heating and dephasing effects, the energy introduced by non-adiabaticity and heating, and the thermalisation of the system after an application of amplitude noise on the lattice. The third topic is to design quantum algorithms to solve classical problems of fluid dynamics. We develop a quantum algorithm based around phase estimation that can be tailored to specific fluid dynamics problems and demonstrate a quantum speed up over classical Monte Carlo methods. This generates new bridge between quantum physics and fluid dynamics engineering, can be used to estimate the potential impact of quantum computers and provides feedback on requirements for implementing quantum algorithms on quantum devices.
Download or read book U Paris written by and published by . This book was released on 2013 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Macroscopic Quantum Coherence and Quantum Computing written by Dmitri V. Averin and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 459 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is an outgrowth of the Second International Workshop on Macroscopic Quantum Coherence and Computing held in Napoli, Italy, in June 2000. This workshop gathered a number of experts from the major Universities and Research Institutions of several countries. The choice of the location, which recognizes the role and the traditions of Naples in this field, guaranteed the participants a stimulating atmosphere. The aim of the workshop has been to report on the recent theoretical and experimental results on the macroscopic quantum coherence of macroscopic systems. Particular attention was devoted to Josephson devices. The correlation with other atomic and molecular systems, exhibiting a macroscopic quantum behaviour, was also discussed. The seminars provided both historical overview and recent theoretical ground on the topic, as well as information on new experimental results relative to the quantum computing area. The first workshop on this topic, held in Napoli in 1998, has been ennobled by important reports on observations of Macroscopic Quantum Coherence in mesoscopic systems. The current workshop proposed, among many stimulating results, the first observations of Macroscopic Quantum Coherence between macroscopically distinct fluxoid states in rf SQUIDs, 20 years after the Leggett's proposal to experimentally test the quantum behavior of macroscopic systems. Reports on observations of quantum behaviour in molecular and magnetic systems, small Josephson devices, quantum dots have also been particularly stimulating in view of the realization of several possible q-bits.
Download or read book Adiabatic Quantum Computing from an Eigenvalue Dynamics Point of View written by Richard D. Wilson and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book APS 4CS Adiabatic Quantum Computing written by and published by . This book was released on 2012 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
