Techniques for Noise Suppression and Robust Control in Spin-based Quantum Information Processors

Techniques for Noise Suppression and Robust Control in Spin-based Quantum Information Processors
Author: Troy William Borneman
Publisher:
Total Pages: 160
Release: 2013
Genre:
ISBN:

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Processing information quantum mechanically allows the relatively efficient solution of many important problems thought to be intractable on a classical computer. A primary challenge in experimentally implementing a quantum information processor is the control and suppression of environmental noise that decoheres the quantum system and causes it to behave classically. Environmental errors may be dynamically suppressed by applying coherent control pulses to the qubits that decouple the environment. However, the pulses themselves are subject to implementation errors, which hinders the ability to robustly store a complete quantum state. This thesis details results on the use of optimal control theory, noise twirling, and logical qubit encodings to design high-fidelity control pulses and decoupling sequences that are robust to implementation errors. Results are also presented that demonstrate how high-fidelity inductive control of a quantum system may be obtained with limited resonator bandwidth, with a discussion of applications to actuator-based quantum information processors. In a multi-mode design for such a processor, which allows efficient removal of entropy, a new protocol is suggested that permits robust parallel information transfer between nodes. The results detailed in this thesis apply broadly to most implementations of quantum information processing and specifically enable a new design for a spin-based multinode quantum information processor based on single-crystal molecular monolayer electron-nuclear spin systems integrated with superconducting electronics.

Robust Control for Quantum Technologies and Quantum Information Processing

Robust Control for Quantum Technologies and Quantum Information Processing
Author: Xavier Jacques Laforgue
Publisher:
Total Pages: 0
Release: 2022
Genre:
ISBN:

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We consider the robust inverse geometric optimization of arbitrary population transfers and single-qubit gates in a two-level system.Robustness with respect to pulse inhomogeneities is demonstrated.We show that for time or energy optimization, the pulse amplitude is constant, and we provide the analytic form of the detuning as Jacobi elliptic cosine.We deal with the task of robust complete population transfer on a 3-level quantum system in lambda configuration.First, we use the Lewis-Riesenfeld method to derive a family of solutions leading to an exact transfer.Among this family, we identify a tracking solution with a single parameter to control simultaneously the fidelity of the transfer, the population of the excited state, and robustness.The ultrahigh-fidelity robustness of the shaped pulses is found superior to that of Gaussian and adiabatically-optimized pulses for moderate pulse areas.Second, we apply robust inverse optimization now to generate a stimulated Raman exact passage (STIREP)considering the loss of the upper state as a characterization parameter.Control fields temporal shapes, robust against pulse inhomogeneities, that are optimal with respect to pulse area, energy, and duration, are found to form a simple sequence with a combination of intuitively (near the beginning and the end) and counter-intuitively ordered pulse pairs.Alternative robust optimal solutions featuring lower losses, larger pulse areas, and fully counter-intuitive pulse sequences are derived.

Quantum Information With Continuous Variables Of Atoms And Light

Quantum Information With Continuous Variables Of Atoms And Light
Author: Nicolas J Cerf
Publisher: World Scientific
Total Pages: 629
Release: 2007-02-06
Genre: Science
ISBN: 1908979364

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Quantum information describes the new field which bridges quantum physics and information science. The quantum world allows for completely new architectures and protocols. While originally formulated in continuous quantum variables, the field worked almost exclusively with discrete variables, such as single photons and photon pairs. The renaissance of continuous variables came with European research consortia such as ACQUIRE (Advanced Coherent Quantum Information Research) in the late 1990s, and QUICOV (Quantum Information with Continuous Variables) from 2000-2003. The encouraging research results of QUICOV and the new conference series CVQIP (Continuous Variable Quantum Information Processing) triggered the idea for this book.This book presents the state of the art of quantum information with continuous quantum variables. The individual chapters discuss results achieved in QUICOV and presented at the first five CVQIP conferences from 2002-2006. Many world-leading scientists working on continuous variables outside Europe also contribute to the book./a

Computer Aided Verification

Computer Aided Verification
Author: Alexandra Silva
Publisher: Springer Nature
Total Pages: 922
Release: 2021-07-17
Genre: Computers
ISBN: 3030816850

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This open access two-volume set LNCS 12759 and 12760 constitutes the refereed proceedings of the 33rd International Conference on Computer Aided Verification, CAV 2021, held virtually in July 2021. The 63 full papers presented together with 16 tool papers and 5 invited papers were carefully reviewed and selected from 290 submissions. The papers were organized in the following topical sections: Part I: invited papers; AI verification; concurrency and blockchain; hybrid and cyber-physical systems; security; and synthesis. Part II: complexity and termination; decision procedures and solvers; hardware and model checking; logical foundations; and software verification. This is an open access book.

Controlling Quantum Systems for Quantum Information Processing

Controlling Quantum Systems for Quantum Information Processing
Author: Kevin Christopher Young
Publisher:
Total Pages: 292
Release: 2010
Genre:
ISBN:

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For several decades it has been appreciated that quantum computers hold incredible promise to perform calculations intractable to classical computation. However, this promise has be slow to realize. Dozens of quantum systems are currently being investigated for use in quantum information processing - none of which have yet demonstrated algorithms involving more than a handful of qubits and it remains unclear which, if any, of these systems will ultimately compose a scalable, robust quantum information processing architecture. In this thesis we employ analytical, optimal and algebraic control techniques to evaluate various quantum systems for their potential use in quantum information processing. In doing so, we have additionally identified several novel characterization procedures capable of probing both the coherent and incoherent dynamics of quantum systems. The first part of this thesis discusses work motivated by attempts to utilize donor qubits in silicon as quantum bits. We first propose a measurement of the state of a single donor electron spin using two-dimensional electron gas of a field-effect transistor and electrically detected magnetic resonance. We analyze the potential sensitivity of this measurement and show that it is a quantum nondemolition measurement of an electron-encoded state. We then present the first of two novel qubit characterization procedures. We consider the problem of rapidly characterizing a large number of similarly prepared qubits using techniques from optimal experiment design. All qubits are assumed to evolve according to the same physical processes, though the Hamiltonian parameters may vary from device to device - an inevitability in solid state qubits. We use the Cram\'er-Rao bound on the variance of a point estimator to construct the optimal series of experiments to estimate these free parameters, and present a complete analysis of the optimal experimental configuration. Though applied to dipole- and exchange-coupled qubits, this technique is widely applicable to other systems. The second part of the thesis discusses the role that control can play in measuring and mitigating noise in qubit systems. Our first result describes a method for quickly simulating the effects of arbitrary markovian noise on qubit systems through the use of a numerically optimized, multi-state Markovian fluctuator. This ability to rapidly simulate the noisy qubit evolution allows us to compute control sequences capable of maximally decoupling the qubit from the noise source. We then introduce the second characterization procedure of the these, showing that a single measurable and controllable qubit may act as a spectrometer of dephasing noise. We show that the formalism of dynamical decoupling can be used to estimate the short-time correlation function of the noise source, while long time correlations may be estimated by a very simple series of free evolution experiments. This technique is applicable to the wide range of physical implementations which suffer from dephasing noise. The final part of this thesis demonstrates that trapped neutral atoms may be utilized for the robust simulation of complex systems exhibiting a topological phase. We present a method to simulate the toric code Hamiltonian stroboscopically, and demonstrate that our technique preserves the ground state degeneracy . Furthermore, we introduce a dissipative mechanism allowing for thermalization of the system to a finite temperature or direct cooling to the ground state manifold.

Encyclopaedia of Mathematics, Supplement III

Encyclopaedia of Mathematics, Supplement III
Author: Michiel Hazewinkel
Publisher: Springer Science & Business Media
Total Pages: 564
Release: 2007-11-23
Genre: Mathematics
ISBN: 0306483734

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This is the third supplementary volume to Kluwer's highly acclaimed twelve-volume Encyclopaedia of Mathematics. This additional volume contains nearly 500 new entries written by experts and covers developments and topics not included in the previous volumes. These entries are arranged alphabetically throughout and a detailed index is included. This supplementary volume enhances the existing twelve volumes, and together, these thirteen volumes represent the most authoritative, comprehensive and up-to-date Encyclopaedia of Mathematics available.

Decoherence Suppression in Quantum Systems 2008

Decoherence Suppression in Quantum Systems 2008
Author: Mikio Nakahara
Publisher: World Scientific
Total Pages: 202
Release: 2010
Genre: Science
ISBN: 9814295833

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While innovative ideas and creative works increasingly drive economic success, the historic approach to encouraging innovation and creativity by granting property rights has come under attack by a growing number of legal theorists and technologists. In Laws of Creation, Ronald Cass and Keith Hylton take on these critics with a vigorous defense of intellectual property law. The authors look closely at the IP doctrines that have been developed over many years in patent, copyright, trademark, and trade secret law. In each area, legislatures and courts have weighed the benefits that come from preserving incentives to innovate against the costs of granting innovators a degree of control over specific markets. Over time, the authors show, a set of rules has emerged that supports wealth-creating innovation while generally avoiding overly expansive, growth-retarding licensing regimes. These rules are now under pressure from detractors who claim that changing technology undermines the case for intellectual property rights. But Cass and Hylton explain how technological advances only strengthen that case. In their view, the easier it becomes to copy innovations, the harder to detect copies and to stop copying, the greater the disincentive to invest time and money in inventions and creative works. The authors argue convincingly that intellectual property laws help create a society that is wealthier and inspires more innovation than those of alternative legal systems. Ignoring the social value of intellectual property rights and making what others create and nurture âeoefreeâe would be a costly mistake indeed.

Quantum Inspired Computational Intelligence

Quantum Inspired Computational Intelligence
Author: Siddhartha Bhattacharyya
Publisher: Morgan Kaufmann
Total Pages: 508
Release: 2016-09-20
Genre: Computers
ISBN: 0128044373

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Quantum Inspired Computational Intelligence: Research and Applications explores the latest quantum computational intelligence approaches, initiatives, and applications in computing, engineering, science, and business. The book explores this emerging field of research that applies principles of quantum mechanics to develop more efficient and robust intelligent systems. Conventional computational intelligence—or soft computing—is conjoined with quantum computing to achieve this objective. The models covered can be applied to any endeavor which handles complex and meaningful information. Brings together quantum computing with computational intelligence to achieve enhanced performance and robust solutions Includes numerous case studies, tools, and technologies to apply the concepts to real world practice Provides the missing link between the research and practice