The Experts below are selected from a list of 104613 Experts worldwide ranked by ideXlab platform
Herschel Rabitz - One of the best experts on this subject based on the ideXlab platform.
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Systematically altering the apparent topology of constrained Quantum Control landscapes
Journal of Mathematical Chemistry, 2014Co-Authors: Ashley Donovan, Herschel RabitzAbstract:A Quantum Control experiment typically seeks a shaped electromagnetic field to drive a system towards a specified observable objective. The large number of successful experiments can be understood through an exploration of the underlying Quantum Control landscape, which maps the objective as a function of the Control variables. Specifically, under certain assumptions, the Control landscape lacks suboptimal traps that could prevent identification of an optimal Control. One of these assumptions is that there are no restrictions on the Control variables, however, in practice Control resources are inevitably constrained. The associated constrained Quantum Control landscape may be difficult to freely traverse due to the presence of limited resource induced traps. This work develops algorithms to (1) seek optimal Controls under restricted resources, (2) explore the nature of apparent suboptimal landscape topology, and (3) favorably alter trap topology through systematic relaxation of the constraints. A set of mathematical tools are introduced to meet these needs by working directly with dynamic Controls, rather than the prior studies that employed intermediate so-called kinematic Control variables. The new tools are illustrated using few-level systems showing the capability of systematically relaxing constraints to convert an isolated trap into a level set or saddle feature on the landscape, thereby opening up the ability to find new solutions including those of higher fidelity. The results indicate the richness and complexity of the constrained Quantum Control landscape upon considering the tradeoff between resources and freedom to move on the landscape.
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Exploring Quantum Control landscape structure
Physical Review A, 2013Co-Authors: Arun Nanduri, Ashley Donovan, Herschel RabitzAbstract:A common goal of Quantum Control is to maximize a physical observable through the application of a tailored field. The observable value as a function of the field constitutes a Quantum-Control landscape. Previous papers have shown, under specified conditions, that the Quantum-Control landscape should be free of suboptimal critical points. This favorable landscape topology is one factor contributing to the efficiency of climbing the landscape. An additional complementary factor is the landscape structure, which constitutes all nontopological features. If the landscape's structure is too complex, then climbs may be forced to take inefficient convoluted routes to find optimal Controls. This paper provides a foundation for understanding Control-landscape structure by examining the linearity of gradient-based optimization trajectories through the space of Control fields. For this assessment, a metric $R\ensuremath{\ge}1$ is defined as the ratio of the path length of the optimization trajectory to the Euclidean distance between the initial Control field and the resultant optimal Control field that takes an observable from the bottom to the top of the landscape. Computational analyses for simple model Quantum systems are performed to ascertain the relative abundance of nearly straight Control trajectories encountered when optimizing a state-to-state transition probability. The distribution of $R$ values is found to be centered near remarkably low values upon sampling large numbers of randomly chosen initial Control fields. Additionally, a stochastic algorithm is used to locate many distinct initial Control fields, each of which corresponds to the start of an almost straight Control trajectory with $R\ensuremath{\simeq}1.0$. The collected results indicate that Quantum-Control landscapes have very simple structural features. The favorable topology and the complementary simple structure of the Control landscape provide a basis for understanding the generally observed ease of optimizing a state-to-state transition probability.
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Singularities of Quantum Control landscapes
Physical Review A, 2012Co-Authors: Ruixing Long, Jason Dominy, Herschel RabitzAbstract:A Quantum Control landscape is defined as the objective to be optimized as a function of the Control variables. Existing empirical and theoretical studies reveal that most realistic Quantum Control landscapes are generally devoid of false traps. However, the impact of singular Controls has yet to be investigated, which can arise due to a singularity on the mapping from the Control to the final Quantum state. We provide an explicit characterization of such Controls that are strongly Hamiltonian-dependent and investigate their associated landscape geometry. Although in principle the singularities may correspond to local traps, we did not find any in numerical simulations. Also, as they occupy a small portion of the entire set of possible critical Controls, their influence is expected to be much smaller than Controls corresponding to the commonly located regular extremals. This observation supports the established ease of optimal searches to find high-quality Controls in simulations and experiments.
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Critical points of the optimal Quantum Control landscape: a propagator approach
Acta Applicandae Mathematicae, 2012Co-Authors: Herschel Rabitz, Gabriel TuriniciAbstract:Numerical and experimental realizations of Quantum Control are closely connected to the properties of the mapping from the Control to the unitary propagator. For bilinear Quantum Control problems, no general results are available to fully determine when this mapping is singular or not. In this paper we give suffcient conditions, in terms of elements of the evolution semigroup, for a trajectory to be non-singular. We identify two lists of "way-points" that, when reached, ensure the non-singularity of the Control trajectory. It is found that under appropriate hypotheses one of those lists does not depend on the values of the coupling operator matrix.
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Quantum Control of tightly competitive product channels.
Physical review letters, 2009Co-Authors: Matthias Roth, Jonathan Roslund, Laurent Guyon, Véronique Boutou, Françoise Courvoisier, Jean-pierre Wolf, Herschel RabitzAbstract:Fundamental selectivity limits of Quantum Control are pushed by introducing laser driven optimal dynamic discrimination to create distinguishing excitations on two nearly identical flavin molecules. Even with modest spectral resources, significant specificity is achieved with optimal pulse shapes, which amplify small molecular differences to create distinct, identifying signals. Rather than being a hindrance, system complexity appears to aid the Control process and augments Control field capability, which bodes well for implementation of Quantum Control in a variety of demanding applications.
Daoyi Dong - One of the best experts on this subject based on the ideXlab platform.
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Quantum Control theory and applications a survey
Iet Control Theory and Applications, 2010Co-Authors: Daoyi Dong, Ian R. PetersenAbstract:This study presents a survey on Quantum Control theory and applications from a Control systems perspective. Some of the basic concepts and main developments (including open-loop Control and closed-loop Control) in Quantum Control theory are reviewed. In the area of open-loop Quantum Control, the paper surveys the notion of Controllability for Quantum systems and presents several Control design strategies including optimal Control, Lyapunov-based methodologies, variable structure Control and Quantum incoherent Control. In the area of closed-loop Quantum Control, this study reviews closed-loop learning Control and several important issues related to Quantum feedback Control including Quantum filtering, feedback stabilisation, linear-quadratic-Gaussian Control and robust Quantum Control.
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Quantum Control theory and applications: A survey
IET Control Theory & Applications, 2010Co-Authors: Daoyi Dong, Ian R. PetersenAbstract:This paper presents a survey on Quantum Control theory and applications from a Control systems perspective. Some of the basic concepts and main developments (including open-loop Control and closed-loop Control) in Quantum Control theory are reviewed. In the area of open-loop Quantum Control, the paper surveys the notion of Controllability for Quantum systems and presents several Control design strategies including optimal Control, Lyapunov-based methodologies, variable structure Control and Quantum incoherent Control. In the area of closed-loop Quantum Control, the paper reviews closed-loop learning Control and several important issues related to Quantum feedback Control including Quantum filtering, feedback stabilization, LQG Control and robust Quantum Control.
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Quantum Control BASED ON Quantum INFORMATION
International Journal of Modern Physics B, 2007Co-Authors: Zonghai Chen, Chenbin Zhang, Daoyi DongAbstract:Quantum Control strategy is discussed from the perspective of Quantum information. First, the constraints imposed on Quantum Control by Quantum theory are analyzed. Then some Quantum Control schemes based on Quantum information are discussed, such as teleportation-based distant Quantum Control, Quantum feedback Control using Quantum cloning and state recognition, Quantum Control based on measurement and Grover iteration. Finally, some applications of Quantum Control theory in Quantum information and Quantum computation such as Quantum error correction coding, universality analysis of Quantum computation, feedback-induced entanglement enhancement, etc., are presented and the potential applications of Quantum Control are also prospected.
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Quantum Control Based on Quantum Information
2006 Chinese Control Conference, 2006Co-Authors: Zonghai Chen, Daoyi Dong, Chenbin ZhangAbstract:Quantum Control strategy is discussed from the perspective of Quantum information. First, the constraints imposed on the Quantum Control by Quantum theory are analyzed. Then some Quantum Control schemes based on Quantum information are discussed, such as teleportation-based distant Quantum Control, Quantum feedback Control using Quantum cloning and state recognition, Quantum Control based on measurement and Grover iteration. Finally, some applications of Quantum Control in Quantum error correction coding and universality analysis of Quantum computation are presented and the potential applications of Quantum Control in Quantum information and Quantum computation are also prospected.
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Research on modeling and simulation of Quantum Control systems
Fifth World Congress on Intelligent Control and Automation (IEEE Cat. No.04EX788), 1Co-Authors: Daoyi Dong, Zonghai ChenAbstract:Quantum Control theory is a new interdiscipline, which mainly concerns how to Control Quantum states of microsystems. To get better Control results, it is necessary to study the modeling and simulation of the systems. With the consideration of the characteristics of Quantum Control, direct mechanism modeling and quantization modeling for Quantum Control systems are studied, and simulation of Quantum Control systems is also analyzed. Direct mechanism modeling uses the mechanism information of systems in Quantum physics and suitably models some Quantum Control systems with the known mechanism. Quantization modeling makes the most of the corresponding relations between Quantum operators and classical physical quantities, and uses the information of models in classical Control to establish the corresponding models in Quantum Control.
K J Satzinger - One of the best experts on this subject based on the ideXlab platform.
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Quantum Control of surface acoustic wave phonons
Nature, 2018Co-Authors: K J Satzinger, Youpeng Zhong, Hungshen Chang, G A Peairs, Audrey Bienfait, Minghan Chou, A Y Cleland, C R ConnerAbstract:One of the hallmarks of Quantum physics is the generation of non-classical Quantum states and superpositions, which has been demonstrated in several Quantum systems, including ions, solid-state qubits and photons. However, only indirect demonstrations of non-classical states have been achieved in mechanical systems, despite the scientific appeal and technical utility of such a capability1,2, including in Quantum sensing, computation and communication applications. This is due in part to the highly linear response of most mechanical systems, which makes Quantum operations difficult, as well as their characteristically low frequencies, which hinder access to the Quantum ground state3-7. Here we demonstrate full Quantum Control of the mechanical state of a macroscale mechanical resonator. We strongly couple a surface acoustic-wave8 resonator to a superconducting qubit, using the qubit to Control and measure Quantum states in the mechanical resonator. We generate a non-classical superposition of the zero- and one-phonon Fock states and map this and other states using Wigner tomography9-14. Such precise, programmable Quantum Control is essential to a range of applications of surface acoustic waves in the Quantum limit, including the coupling of disparate Quantum systems15,16.
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Quantum Control of surface acoustic wave phonons
arXiv: Quantum Physics, 2018Co-Authors: K J Satzinger, Youpeng Zhong, Hungshen Chang, G A Peairs, Audrey Bienfait, Minghan Chou, A Y Cleland, C R ConnerAbstract:The superposition of Quantum states is one of the hallmarks of Quantum physics, and clear demonstrations of superposition have been achieved in a number of Quantum systems. However, mechanical systems have remained a challenge, with only indirect demonstrations of mechanical state superpositions, in spite of the intellectual appeal and technical utility such a capability would bring. This is due in part to the highly linear response of most mechanical systems, making Quantum operation difficult, as well as their characteristically low frequencies, making it difficult to reach the Quantum ground state. In this work, we demonstrate full Quantum Control of the mechanical state of a macroscopic mechanical resonator. We strongly couple a surface acoustic wave resonator to a superconducting qubit, using the qubit to Control and measure Quantum states in the mechanical resonator. Most notably, we generate a Quantum superposition of the zero and one phonon states and map this and other states using Wigner tomography. This precise, programmable Quantum Control is essential to a range of applications of surface acoustic waves in the Quantum limit, including using surface acoustic waves to couple disparate Quantum systems.
Fuguo Deng - One of the best experts on this subject based on the ideXlab platform.
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fast and robust Quantum Control for multimode interactions using shortcuts to adiabaticity
Optics Express, 2019Co-Authors: Hao Zhang, Xueke Song, Haibo Wang, Guojian Yang, Fuguo DengAbstract:Adiabatic Quantum Control is a very important approach for Quantum physics and Quantum information processing (QIP). It holds the advantage with robustness to experimental imperfections but accumulates more decoherence due to the long evolution time. Here, we propose a universal protocol for fast and robust Quantum Control in multimode interactions of a Quantum system by using shortcuts to adiabaticity. The results show this protocol can speed up the evolution of a multimode Quantum system effectively, and it can also keep the robustness very good while adiabatic Quantum Control processes cannot. We apply this protocol for the Quantum state transfer in QIP in the photon-phonon interactions in an optomechanical system, showing a perfect result. These good features make this protocol have the capability of improving effectively the feasibility of the practical applications of multimode interactions in QIP in experiment.
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Fast and robust Quantum Control for multimode interactions by using shortcuts to adiabaticity
Optics express, 2019Co-Authors: Hao Zhang, Xueke Song, Haibo Wang, Guojian Yang, Fuguo DengAbstract:Adiabatic Quantum Control is a very important approach for Quantum physics and Quantum information processing. It holds the advantage with robustness to experimental imperfections but accumulates more decoherence due to the long evolution time. Here, we propose a universal protocol for fast and robust Quantum Control in multimode interactions of a Quantum system by using shortcuts to adiabaticity. The results show this protocol can speed up the evolution of a multimode Quantum system effectively, and it can also keep the robustness very good while adiabatic Quantum Control processes cannot. We apply this protocol for the Quantum state transfer in Quantum information processing in the photon-phonon interactions in an optomechanical system, showing a perfect result. These good features make this protocol have the capability of improving effectively the feasibility of the practical applications of multimode interactions in Quantum information processing in experiment.
Albert Schliesser - One of the best experts on this subject based on the ideXlab platform.
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Measurement-based Quantum Control of mechanical motion
Nature, 2018Co-Authors: Massimiliano Rossi, Yeghishe Tsaturyan, Junxin Chen, David Mason, Albert SchliesserAbstract:Controlling a Quantum system by using observations of its dynamics is complicated by the backaction of the measurement process—that is, the unavoidable Quantum disturbance caused by coupling the system to a measurement apparatus. An efficient measurement is one that maximizes the amount of information gained per disturbance incurred. Real-time feedback can then be used to cancel the backaction of the measurement and to Control the evolution of the Quantum state. Such measurement-based Quantum Control has been demonstrated in the clean settings of cavity and circuit Quantum electrodynamics, but its application to motional degrees of freedom has remained elusive. Here we demonstrate measurement-based Quantum Control of the motion of a millimetre-sized membrane resonator. An optomechanical transducer resolves the zero-point motion of the resonator in a fraction of its millisecond-scale coherence time, with an overall measurement efficiency close to unity. An electronic feedback loop converts this position record to a force that cools the resonator mode to its Quantum ground state (residual thermal occupation of about 0.29). This occupation is nine decibels below the Quantum-backaction limit of sideband cooling and six orders of magnitude below the equilibrium occupation of the thermal environment. We thus realize a long-standing goal in the field, adding position and momentum to the degrees of freedom that are amenable to measurement-based Quantum Control, with potential applications in Quantum information processing and gravitational-wave detectors.The displacement of a mechanical resonator is measured to within 35% of the Heisenberg uncertainty limit, enabling feedback cooling to the Quantum ground state, nine decibels below the Quantum-backaction limit.
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Measurement-based Quantum Control of mechanical motion
Nature, 2018Co-Authors: Massimiliano Rossi, Yeghishe Tsaturyan, Junxin Chen, David Mason, Albert SchliesserAbstract:Controlling a Quantum system based on the observation of its dynamics is inevitably complicated by the backaction of the measurement process. Efficient measurements, however, maximize the amount of information gained per disturbance incurred. Real-time feedback then enables both canceling the measurement's backaction and Controlling the evolution of the Quantum state. While such measurement-based Quantum Control has been demonstrated in the clean settings of cavity and circuit Quantum electrodynamics, its application to motional degrees of freedom has remained elusive. Here we show measurement-based Quantum Control of the motion of a millimetre-sized membrane resonator. An optomechanical transducer resolves the zero-point motion of the soft-clamped resonator in a fraction of its millisecond coherence time, with an overall measurement efficiency close to unity. We use this position record to feedback-cool a resonator mode to its Quantum ground state (residual thermal occupation n = 0.29 +- 0.03), 9 dB below the Quantum backaction limit of sideband cooling, and six orders of magnitude below the equilibrium occupation of its thermal environment. This realizes a long-standing goal in the field, and adds position and momentum to the degrees of freedom amenable to measurement-based Quantum Control, with potential applications in Quantum information processing and gravitational wave detectors.
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measurement based Quantum Control of mechanical motion
Nature, 2018Co-Authors: Massimiliano Rossi, Yeghishe Tsaturyan, Junxin Chen, David Mason, Albert SchliesserAbstract:Controlling a Quantum system by using observations of its dynamics is complicated by the backaction of the measurement process—that is, the unavoidable Quantum disturbance caused by coupling the system to a measurement apparatus. An efficient measurement is one that maximizes the amount of information gained per disturbance incurred. Real-time feedback can then be used to cancel the backaction of the measurement and to Control the evolution of the Quantum state. Such measurement-based Quantum Control has been demonstrated in the clean settings of cavity and circuit Quantum electrodynamics, but its application to motional degrees of freedom has remained elusive. Here we demonstrate measurement-based Quantum Control of the motion of a millimetre-sized membrane resonator. An optomechanical transducer resolves the zero-point motion of the resonator in a fraction of its millisecond-scale coherence time, with an overall measurement efficiency close to unity. An electronic feedback loop converts this position record to a force that cools the resonator mode to its Quantum ground state (residual thermal occupation of about 0.29). This occupation is nine decibels below the Quantum-backaction limit of sideband cooling and six orders of magnitude below the equilibrium occupation of the thermal environment. We thus realize a long-standing goal in the field, adding position and momentum to the degrees of freedom that are amenable to measurement-based Quantum Control, with potential applications in Quantum information processing and gravitational-wave detectors.
