1
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Jones JA. Controlling NMR spin systems for quantum computation. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2024; 140-141:49-85. [PMID: 38705636 DOI: 10.1016/j.pnmrs.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 02/05/2024] [Indexed: 05/07/2024]
Abstract
Nuclear magnetic resonance is arguably both the best available quantum technology for implementing simple quantum computing experiments and the worst technology for building large scale quantum computers that has ever been seriously put forward. After a few years of rapid growth, leading to an implementation of Shor's quantum factoring algorithm in a seven-spin system, the field started to reach its natural limits and further progress became challenging. Rather than pursuing more complex algorithms on larger systems, interest has now largely moved into developing techniques for the precise and efficient manipulation of spin states with the aim of developing methods that can be applied in other more scalable technologies and within conventional NMR. However, the user friendliness of NMR implementations means that they remain popular for proof-of-principle demonstrations of simple quantum information protocols.
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Affiliation(s)
- Jonathan A Jones
- Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
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2
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Tutunnikov I, Chuang C, Cao J. Coherent Spatial Control of Wave Packet Dynamics on Quantum Lattices. J Phys Chem Lett 2023; 14:11632-11639. [PMID: 38100722 DOI: 10.1021/acs.jpclett.3c03047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
Abstract
Quantum lattices are pivotal in the burgeoning fields of quantum materials and information science. Novel experimental techniques allow the preparation and monitoring of wave packet dynamics on quantum lattices with high spatiotemporal resolution. We present an analytical study of wave packet diffusivity and diffusion length on tight-binding quantum lattices subject to stochastic noise. Our analysis reveals the crucial role of spatial coherence and predicts a set of novel phenomena: (1) noise can enhance the transient diffusivity and diffusion length of spatially extended initial states; (2) standing or traveling initial states, with large momentum, spread faster than a localized initial state and exhibit a noise-induced peak in the transient diffusivity; (3) the differences in the diffusivity or diffusion length of extended and localized initial states have a universal dependence on initial width. These predictions suggest the possibility of controlling the wave packet dynamics by spatial manipulations, which will have implications for materials science and quantum technologies.
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Affiliation(s)
- Ilia Tutunnikov
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Chern Chuang
- Department of Chemistry and Biochemistry, University of Nevada, 4505 S Maryland Pkwy, Las Vegas, Nevada 89154, United States
| | - Jianshu Cao
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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3
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Rabitz H, Russell B, Ho TS. The Surprising Ease of Finding Optimal Solutions for Controlling Nonlinear Phenomena in Quantum and Classical Complex Systems. J Phys Chem A 2023; 127:4224-4236. [PMID: 37142303 DOI: 10.1021/acs.jpca.3c01896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
This Perspective addresses the often observed surprising ease of achieving optimal control of nonlinear phenomena in quantum and classical complex systems. The circumstances involved are wide-ranging, with scenarios including manipulation of atomic scale processes, maximization of chemical and material properties or synthesis yields, Nature's optimization of species' populations by natural selection, and directed evolution. Natural evolution will mainly be discussed in terms of laboratory experiments with microorganisms, and the field is also distinct from the other domains where a scientist specifies the goal(s) and oversees the control process. We use the word "control" in reference to all of the available variables, regardless of the circumstance. The empirical observations on the ease of achieving at least good, if not excellent, control in diverse domains of science raise the question of why this occurs despite the generally inherent complexity of the systems in each scenario. The key to addressing the question lies in examining the associated control landscape, which is defined as the optimization objective as a function of the control variables that can be as diverse as the phenomena under consideration. Controls may range from laser pulses, chemical reagents, chemical processing conditions, out to nucleic acids in the genome and more. This Perspective presents a conjecture, based on present findings, that the systematics of readily finding good outcomes from controlled phenomena may be unified through consideration of control landscapes with the same common set of three underlying assumptions─the existence of an optimal solution, the ability for local movement on the landscape, and the availability of sufficient control resources─whose validity needs assessment in each scenario. In practice, many cases permit using myopic gradient-like algorithms while other circumstances utilize algorithms having some elements of stochasticity or introduced noise, depending on whether the landscape is locally smooth or rough. The overarching observation is that only relatively short searches are required despite the common high dimensionality of the available controls in typical scenarios.
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Affiliation(s)
- Herschel Rabitz
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Benjamin Russell
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Tak-San Ho
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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4
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Information theoretical limits for quantum optimal control solutions: error scaling of noisy control channels. Sci Rep 2022; 12:21405. [PMID: 36496434 PMCID: PMC9741659 DOI: 10.1038/s41598-022-25770-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022] Open
Abstract
Accurate manipulations of an open quantum system require a deep knowledge of its controllability properties and the information content of the implemented control fields. By using tools of information and quantum optimal control theory, we provide analytical bounds (information-time bounds) to characterize our capability to control the system when subject to arbitrary sources of noise. Moreover, since the presence of an external noise field induces open quantum system dynamics, we also show that the results provided by the information-time bounds are in very good agreement with the Kofman-Kurizki universal formula describing decoherence processes. Finally, we numerically test the scaling of the control accuracy as a function of the noise parameters, by means of the dressed chopped random basis (dCRAB) algorithm for quantum optimal control.
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5
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Rahaman S, Nath B, Kumar Mondal C. Design of laser pulse to enhance the photo-dissociation of a tri-atomic molecular system using optimal control theory based adaptive simulated annealing technique. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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6
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A quantum system control method based on enhanced reinforcement learning. Soft comput 2022. [DOI: 10.1007/s00500-022-07179-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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7
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Dong D, Xing X, Ma H, Chen C, Liu Z, Rabitz H. Learning-Based Quantum Robust Control: Algorithm, Applications, and Experiments. IEEE TRANSACTIONS ON CYBERNETICS 2020; 50:3581-3593. [PMID: 31295133 DOI: 10.1109/tcyb.2019.2921424] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Robust control design for quantum systems has been recognized as a key task in quantum information technology, molecular chemistry, and atomic physics. In this paper, an improved differential evolution algorithm, referred to as multiple-samples and mixed-strategy DE (msMS_DE), is proposed to search robust fields for various quantum control problems. In msMS_DE, multiple samples are used for fitness evaluation and a mixed strategy is employed for the mutation operation. In particular, the msMS_DE algorithm is applied to the control problems of: 1) open inhomogeneous quantum ensembles and 2) the consensus goal of a quantum network with uncertainties. Numerical results are presented to demonstrate the excellent performance of the improved machine learning algorithm for these two classes of quantum robust control problems. Furthermore, msMS_DE is experimentally implemented on femtosecond (fs) laser control applications to optimize two-photon absorption and control fragmentation of the molecule CH2BrI. The experimental results demonstrate the excellent performance of msMS_DE in searching for effective fs laser pulses for various tasks.
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8
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Kallush S, Aroch A, Kosloff R. Quantifying the Unitary Generation of Coherence from Thermal Quantum Systems. ENTROPY 2019; 21:e21080810. [PMID: 33267523 PMCID: PMC7515339 DOI: 10.3390/e21080810] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 08/01/2019] [Accepted: 08/16/2019] [Indexed: 11/16/2022]
Abstract
Coherence is associated with transient quantum states; in contrast, equilibrium thermal quantum systems have no coherence. We investigate the quantum control task of generating maximum coherence from an initial thermal state employing an external field. A completely controllable Hamiltonian is assumed allowing the generation of all possible unitary transformations. Optimizing the unitary control to achieve maximum coherence leads to a micro-canonical energy distribution on the diagonal energy representation. We demonstrate such a control scenario starting from a given Hamiltonian applying an external field, reaching the control target. Such an optimization task is found to be trap-less. By constraining the amount of energy invested by the control, maximum coherence leads to a canonical energy population distribution. When the optimization procedure constrains the final energy too tightly, local suboptimal traps are found. The global optimum is obtained when a small Lagrange multiplier is employed to constrain the final energy. Finally, we explore the task of generating coherences restricted to be close to the diagonal of the density matrix in the energy representation.
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Affiliation(s)
- Shimshon Kallush
- Department of Physics and Optical Engineering, ORT-Braude College, 21982 Karmiel, Israel
- The Fritz Haber Research Center, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
- Correspondence:
| | - Aviv Aroch
- The Fritz Haber Research Center, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Ronnie Kosloff
- The Fritz Haber Research Center, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
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9
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Eiles MT, Tong Z, Greene CH. Theoretical Prediction of the Creation and Observation of a Ghost Trilobite Chemical Bond. PHYSICAL REVIEW LETTERS 2018; 121:113203. [PMID: 30265124 DOI: 10.1103/physrevlett.121.113203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Indexed: 06/08/2023]
Abstract
The "trilobite"-type of molecule, predicted in 2000 and observed experimentally in 2015, arises when a Rydberg electron exerts a weak attractive force on a neutral ground state atom. Such molecules have bond lengths exceeding 100 nm. The ultralong-range chemical bond between the two atoms is a nonperturbative linear combination of the many degenerate electronic states associated with high principal quantum numbers, and the resulting electron probability distribution closely resembles a fossil trilobite from antiquity. We show how to coherently engineer this same long-range orbital through a sequence of electric and magnetic field pulses even when the ground-state atom is not present and propose several methods to observe the resulting orbital. The existence of such a ghost chemical bond in which an electron reaches out from one atom to a nonexistent second atom is a consequence of the high level degeneracy.
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Affiliation(s)
- Matthew T Eiles
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA
| | - Zhengjia Tong
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA
| | - Chris H Greene
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA
- Purdue Quantum Center, Purdue University, West Lafayette, Indiana 47907, USA
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10
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Chen C, Dong D, Qi B, Petersen IR, Rabitz H. Quantum Ensemble Classification: A Sampling-Based Learning Control Approach. IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING SYSTEMS 2017; 28:1345-1359. [PMID: 28113872 DOI: 10.1109/tnnls.2016.2540719] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Quantum ensemble classification (QEC) has significant applications in discrimination of atoms (or molecules), separation of isotopes, and quantum information extraction. However, quantum mechanics forbids deterministic discrimination among nonorthogonal states. The classification of inhomogeneous quantum ensembles is very challenging, since there exist variations in the parameters characterizing the members within different classes. In this paper, we recast QEC as a supervised quantum learning problem. A systematic classification methodology is presented by using a sampling-based learning control (SLC) approach for quantum discrimination. The classification task is accomplished via simultaneously steering members belonging to different classes to their corresponding target states (e.g., mutually orthogonal states). First, a new discrimination method is proposed for two similar quantum systems. Then, an SLC method is presented for QEC. Numerical results demonstrate the effectiveness of the proposed approach for the binary classification of two-level quantum ensembles and the multiclass classification of multilevel quantum ensembles.
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11
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Russell B, Rabitz H. Common foundations of optimal control across the sciences: evidence of a free lunch. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2017; 375:rsta.2016.0210. [PMID: 28115607 PMCID: PMC5311431 DOI: 10.1098/rsta.2016.0210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/20/2016] [Indexed: 05/22/2023]
Abstract
A common goal in the sciences is optimization of an objective function by selecting control variables such that a desired outcome is achieved. This scenario can be expressed in terms of a control landscape of an objective considered as a function of the control variables. At the most basic level, it is known that the vast majority of quantum control landscapes possess no traps, whose presence would hinder reaching the objective. This paper reviews and extends the quantum control landscape assessment, presenting evidence that the same highly favourable landscape features exist in many other domains of science. The implications of this broader evidence are discussed. Specifically, control landscape examples from quantum mechanics, chemistry and evolutionary biology are presented. Despite the obvious differences, commonalities between these areas are highlighted within a unified mathematical framework. This mathematical framework is driven by the wide-ranging experimental evidence on the ease of finding optimal controls (in terms of the required algorithmic search effort beyond the laboratory set-up overhead). The full scope and implications of this observed common control behaviour pose an open question for assessment in further work.This article is part of the themed issue 'Horizons of cybernetical physics'.
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Affiliation(s)
- Benjamin Russell
- Department of Chemistry, Princeton University, Princeton, NJ 08540, USA
| | - Herschel Rabitz
- Department of Chemistry, Princeton University, Princeton, NJ 08540, USA
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12
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Wigley PB, Everitt PJ, van den Hengel A, Bastian JW, Sooriyabandara MA, McDonald GD, Hardman KS, Quinlivan CD, Manju P, Kuhn CCN, Petersen IR, Luiten AN, Hope JJ, Robins NP, Hush MR. Fast machine-learning online optimization of ultra-cold-atom experiments. Sci Rep 2016; 6:25890. [PMID: 27180805 PMCID: PMC4867626 DOI: 10.1038/srep25890] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 04/21/2016] [Indexed: 12/04/2022] Open
Abstract
We apply an online optimization process based on machine learning to the production of Bose-Einstein condensates (BEC). BEC is typically created with an exponential evaporation ramp that is optimal for ergodic dynamics with two-body s-wave interactions and no other loss rates, but likely sub-optimal for real experiments. Through repeated machine-controlled scientific experimentation and observations our ‘learner’ discovers an optimal evaporation ramp for BEC production. In contrast to previous work, our learner uses a Gaussian process to develop a statistical model of the relationship between the parameters it controls and the quality of the BEC produced. We demonstrate that the Gaussian process machine learner is able to discover a ramp that produces high quality BECs in 10 times fewer iterations than a previously used online optimization technique. Furthermore, we show the internal model developed can be used to determine which parameters are essential in BEC creation and which are unimportant, providing insight into the optimization process of the system.
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Affiliation(s)
- P B Wigley
- Quantum Sensors and Atomlaser Lab, Department of Quantum Science, Research School of Physics and Engineering, The Australian National University, Acton, 2601, Australia
| | - P J Everitt
- Quantum Sensors and Atomlaser Lab, Department of Quantum Science, Research School of Physics and Engineering, The Australian National University, Acton, 2601, Australia
| | - A van den Hengel
- Australian Centre for Visual Technologies, University of Adelaide, Adelaide, 5005, Australia
| | - J W Bastian
- School of Computer Science, University of Adelaide, Adelaide, 5005, Australia
| | - M A Sooriyabandara
- Quantum Sensors and Atomlaser Lab, Department of Quantum Science, Research School of Physics and Engineering, The Australian National University, Acton, 2601, Australia
| | - G D McDonald
- Quantum Sensors and Atomlaser Lab, Department of Quantum Science, Research School of Physics and Engineering, The Australian National University, Acton, 2601, Australia
| | - K S Hardman
- Quantum Sensors and Atomlaser Lab, Department of Quantum Science, Research School of Physics and Engineering, The Australian National University, Acton, 2601, Australia
| | - C D Quinlivan
- Quantum Sensors and Atomlaser Lab, Department of Quantum Science, Research School of Physics and Engineering, The Australian National University, Acton, 2601, Australia
| | - P Manju
- Quantum Sensors and Atomlaser Lab, Department of Quantum Science, Research School of Physics and Engineering, The Australian National University, Acton, 2601, Australia
| | - C C N Kuhn
- Quantum Sensors and Atomlaser Lab, Department of Quantum Science, Research School of Physics and Engineering, The Australian National University, Acton, 2601, Australia
| | - I R Petersen
- School of Engineering and Information Technology, University of New South Wales at the Australian Defence Force Academy, Canberra, 2600, Australia
| | - A N Luiten
- Institute for Photonics &Advanced Sensing, School of Physical Sciences,The University of Adelaide, Adelaide, 5005, Australia
| | - J J Hope
- Department of Quantum Science, Australian National University, Canberra, 2601, Australia
| | - N P Robins
- Quantum Sensors and Atomlaser Lab, Department of Quantum Science, Research School of Physics and Engineering, The Australian National University, Acton, 2601, Australia
| | - M R Hush
- School of Engineering and Information Technology, University of New South Wales at the Australian Defence Force Academy, Canberra, 2600, Australia
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13
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Sun Q, Pelczer I, Riviello G, Wu RB, Rabitz H. Identifying and avoiding singularity-induced local traps over control landscapes of spin chain systems. Phys Chem Chem Phys 2015; 17:29714-22. [PMID: 26478216 DOI: 10.1039/c5cp05418d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The wide success of quantum optimal control in experiments and simulations is attributed to the properties of the control landscape, defined by the objective value as a functional of the controls. Prior analysis has shown that on satisfaction of some underlying assumptions, the landscapes are free of suboptimal traps that could halt the search for a global optimum with gradient-based algorithms. However, violation of one particular assumption can give rise to a so-called singular control, possibly bringing about local traps on the corresponding landscapes in some particular situations. This paper theoretically and experimentally demonstrates the existence of singular traps on the landscape in linear spin-1/2 chains with Ising couplings between nearest neighbors and with certain field components set to zero. The results in a two-spin example show how a trap influences the search trajectories passing by it, and how to avoid encountering such traps in practice by choosing sufficiently strong initial control fields. The findings are also discussed in the context of the generally observed success of quantum control.
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Affiliation(s)
- Qiuyang Sun
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
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14
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Talukder S, Sen S, Shandilya BK, Sharma R, Chaudhury P, Adhikari S. Enhancing the branching ratios in the dissociation channels for O(16)O(16)O(18) molecule by designing optimum laser pulses: A study using stochastic optimization. J Chem Phys 2015; 143:144109. [PMID: 26472365 DOI: 10.1063/1.4932333] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We propose a strategy of using a stochastic optimization technique, namely, simulated annealing to design optimum laser pulses (both IR and UV) to achieve greater fluxes along the two dissociating channels (O(18) + O(16)O(16) and O(16) + O(16)O(18)) in O(16)O(16)O(18) molecule. We show that the integrated fluxes obtained along the targeted dissociating channel is larger with the optimized pulse than with the unoptimized one. The flux ratios are also more impressive with the optimized pulse than with the unoptimized one. We also look at the evolution contours of the wavefunctions along the two channels with time after the actions of both the IR and UV pulses and compare the profiles for unoptimized (initial) and optimized fields for better understanding the results that we achieve. We also report the pulse parameters obtained as well as the final shapes they take.
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Affiliation(s)
- Srijeeta Talukder
- Department of Chemistry, University of Calcutta, 92 A P C Road, Kolkata 700 009, India
| | - Shrabani Sen
- Department of Chemistry, Rammohan College, 102/1, Raja Rammohan Sarani, Kolkata 700 009, India
| | - Bhavesh K Shandilya
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
| | - Rahul Sharma
- Department of Chemistry, St. Xavier's College, 30 Mother Teresa Sarani, Kolkata 700 016, India
| | - Pinaki Chaudhury
- Department of Chemistry, University of Calcutta, 92 A P C Road, Kolkata 700 009, India
| | - Satrajit Adhikari
- Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
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15
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Chang BY, Shin S, Sola IR. State-Selective Excitation of Quantum Systems via Geometrical Optimization. J Chem Theory Comput 2015; 11:4005-10. [DOI: 10.1021/acs.jctc.5b00522] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Bo Y. Chang
- School
of Chemistry (BK21+), Seoul National University, Seoul 151-747, Republic of Korea
| | - Seokmin Shin
- School
of Chemistry (BK21+), Seoul National University, Seoul 151-747, Republic of Korea
| | - Ignacio R. Sola
- Departamento
de Química Física, Universidad Complutense, 28040 Madrid, Spain
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16
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Nanduri A, Shir OM, Donovan A, Ho TS, Rabitz H. Exploring the complexity of quantum control optimization trajectories. Phys Chem Chem Phys 2015; 17:334-47. [PMID: 25377547 DOI: 10.1039/c4cp03853c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The control of quantum system dynamics is generally performed by seeking a suitable applied field. The physical objective as a functional of the field forms the quantum control landscape, whose topology, under certain conditions, has been shown to contain no critical point suboptimal traps, thereby enabling effective searches for fields that give the global maximum of the objective. This paper addresses the structure of the landscape as a complement to topological critical point features. Recent work showed that landscape structure is highly favorable for optimization of state-to-state transition probabilities, in that gradient-based control trajectories to the global maximum value are nearly straight paths. The landscape structure is codified in the metric R ≥ 1.0, defined as the ratio of the length of the control trajectory to the Euclidean distance between the initial and optimal controls. A value of R = 1 would indicate an exactly straight trajectory to the optimal observable value. This paper extends the state-to-state transition probability results to the quantum ensemble and unitary transformation control landscapes. Again, nearly straight trajectories predominate, and we demonstrate that R can take values approaching 1.0 with high precision. However, the interplay of optimization trajectories with critical saddle submanifolds is found to influence landscape structure. A fundamental relationship necessary for perfectly straight gradient-based control trajectories is derived, wherein the gradient on the quantum control landscape must be an eigenfunction of the Hessian. This relation is an indicator of landscape structure and may provide a means to identify physical conditions when control trajectories can achieve perfect linearity. The collective favorable landscape topology and structure provide a foundation to understand why optimal quantum control can be readily achieved.
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Affiliation(s)
- Arun Nanduri
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
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17
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Moore Tibbetts K, Rabitz H. Constrained control landscape for population transfer in a two-level system. Phys Chem Chem Phys 2015; 17:3164-78. [DOI: 10.1039/c4cp04792c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Controlling population transfer in a two-level quantum system reveals a landscape with a rich structure containing highly connected optimal regions.
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18
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Rallis CE, Burwitz TG, Andrews PR, Zohrabi M, Averin R, De S, Bergues B, Jochim B, Voznyuk AV, Gregerson N, Gaire B, Znakovskaya I, McKenna J, Carnes KD, Kling MF, Ben-Itzhak I, Wells E. Incorporating real time velocity map image reconstruction into closed-loop coherent control. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:113105. [PMID: 25430096 DOI: 10.1063/1.4899267] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report techniques developed to utilize three-dimensional momentum information as feedback in adaptive femtosecond control of molecular dynamics. Velocity map imaging is used to obtain the three-dimensional momentum map of the dissociating ions following interaction with a shaped intense ultrafast laser pulse. In order to recover robust feedback information, however, the two-dimensional momentum projection from the detector must be inverted to reconstruct the full three-dimensional momentum of the photofragments. These methods are typically slow or require manual inputs and are therefore accomplished offline after the images have been obtained. Using an algorithm based upon an "onion-peeling" (also known as "back projection") method, we are able to invert 1040 × 1054 pixel images in under 1 s. This rapid inversion allows the full photofragment momentum to be used as feedback in a closed-loop adaptive control scheme, in which a genetic algorithm tailors an ultrafast laser pulse to optimize a specific outcome. Examples of three-dimensional velocity map image based control applied to strong-field dissociation of CO and O2 are presented.
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Affiliation(s)
- C E Rallis
- Department of Physics, Augustana College, Sioux Falls, South Dakota 57197, USA
| | - T G Burwitz
- Department of Physics, Augustana College, Sioux Falls, South Dakota 57197, USA
| | - P R Andrews
- Department of Physics, Augustana College, Sioux Falls, South Dakota 57197, USA
| | - M Zohrabi
- J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
| | - R Averin
- Department of Physics, Augustana College, Sioux Falls, South Dakota 57197, USA
| | - S De
- J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
| | - B Bergues
- Max Planck Institute of Quantum Optics, Hans-Kopfermann Strasse 1, D-85748 Garching, Germany
| | - Bethany Jochim
- Department of Physics, Augustana College, Sioux Falls, South Dakota 57197, USA
| | - A V Voznyuk
- Department of Physics, Augustana College, Sioux Falls, South Dakota 57197, USA
| | - Neal Gregerson
- Department of Physics, Augustana College, Sioux Falls, South Dakota 57197, USA
| | - B Gaire
- J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
| | - I Znakovskaya
- Max Planck Institute of Quantum Optics, Hans-Kopfermann Strasse 1, D-85748 Garching, Germany
| | - J McKenna
- J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
| | - K D Carnes
- J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
| | - M F Kling
- J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
| | - I Ben-Itzhak
- J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
| | - E Wells
- Department of Physics, Augustana College, Sioux Falls, South Dakota 57197, USA
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Shir OM, Roslund J, Whitley D, Rabitz H. Efficient retrieval of landscape Hessian: forced optimal covariance adaptive learning. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 89:063306. [PMID: 25019911 DOI: 10.1103/physreve.89.063306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Indexed: 06/03/2023]
Abstract
Knowledge of the Hessian matrix at the landscape optimum of a controlled physical observable offers valuable information about the system robustness to control noise. The Hessian can also assist in physical landscape characterization, which is of particular interest in quantum system control experiments. The recently developed landscape theoretical analysis motivated the compilation of an automated method to learn the Hessian matrix about the global optimum without derivative measurements from noisy data. The current study introduces the forced optimal covariance adaptive learning (FOCAL) technique for this purpose. FOCAL relies on the covariance matrix adaptation evolution strategy (CMA-ES) that exploits covariance information amongst the control variables by means of principal component analysis. The FOCAL technique is designed to operate with experimental optimization, generally involving continuous high-dimensional search landscapes (≳30) with large Hessian condition numbers (≳10^{4}). This paper introduces the theoretical foundations of the inverse relationship between the covariance learned by the evolution strategy and the actual Hessian matrix of the landscape. FOCAL is presented and demonstrated to retrieve the Hessian matrix with high fidelity on both model landscapes and quantum control experiments, which are observed to possess nonseparable, nonquadratic search landscapes. The recovered Hessian forms were corroborated by physical knowledge of the systems. The implications of FOCAL extend beyond the investigated studies to potentially cover other physically motivated multivariate landscapes.
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Affiliation(s)
- Ofer M Shir
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Jonathan Roslund
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Darrell Whitley
- Department of Computer Science, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Herschel Rabitz
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
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20
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Chen C, Dong D, Li HX, Chu J, Tarn TJ. Fidelity-based probabilistic Q-learning for control of quantum systems. IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING SYSTEMS 2014; 25:920-933. [PMID: 24808038 DOI: 10.1109/tnnls.2013.2283574] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The balance between exploration and exploitation is a key problem for reinforcement learning methods, especially for Q-learning. In this paper, a fidelity-based probabilistic Q-learning (FPQL) approach is presented to naturally solve this problem and applied for learning control of quantum systems. In this approach, fidelity is adopted to help direct the learning process and the probability of each action to be selected at a certain state is updated iteratively along with the learning process, which leads to a natural exploration strategy instead of a pointed one with configured parameters. A probabilistic Q-learning (PQL) algorithm is first presented to demonstrate the basic idea of probabilistic action selection. Then the FPQL algorithm is presented for learning control of quantum systems. Two examples (a spin-1/2 system and a Λ-type atomic system) are demonstrated to test the performance of the FPQL algorithm. The results show that FPQL algorithms attain a better balance between exploration and exploitation, and can also avoid local optimal policies and accelerate the learning process.
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21
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Moore Tibbetts K, Xing X, Rabitz H. Exploring control landscapes for laser-driven molecular fragmentation. J Chem Phys 2013; 139:144201. [DOI: 10.1063/1.4824153] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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22
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Chen C, Wang LC, Wang Y. Closed-loop and robust control of quantum systems. ScientificWorldJournal 2013; 2013:869285. [PMID: 23997680 PMCID: PMC3749599 DOI: 10.1155/2013/869285] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 07/16/2013] [Indexed: 11/27/2022] Open
Abstract
For most practical quantum control systems, it is important and difficult to attain robustness and reliability due to unavoidable uncertainties in the system dynamics or models. Three kinds of typical approaches (e.g., closed-loop learning control, feedback control, and robust control) have been proved to be effective to solve these problems. This work presents a self-contained survey on the closed-loop and robust control of quantum systems, as well as a brief introduction to a selection of basic theories and methods in this research area, to provide interested readers with a general idea for further studies. In the area of closed-loop learning control of quantum systems, we survey and introduce such learning control methods as gradient-based methods, genetic algorithms (GA), and reinforcement learning (RL) methods from a unified point of view of exploring the quantum control landscapes. For the feedback control approach, the paper surveys three control strategies including Lyapunov control, measurement-based control, and coherent-feedback control. Then such topics in the field of quantum robust control as H(∞) control, sliding mode control, quantum risk-sensitive control, and quantum ensemble control are reviewed. The paper concludes with a perspective of future research directions that are likely to attract more attention.
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Affiliation(s)
- Chunlin Chen
- Department of Control and System Engineering, Nanjing University, Nanjing 210093, China
| | - Lin-Cheng Wang
- School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, China
| | - Yuanlong Wang
- Institute of Cyber-Systems and Control, State Key Laboratory of Industrial Control Technology, Zhejiang University, Hangzhou 310027, China
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23
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Shandilya BK, Sen S, Sahoo T, Talukder S, Chaudhury P, Adhikari S. Selective bond breaking mediated by state specific vibrational excitation in model HOD molecule through optimized femtosecond IR pulse: A simulated annealing based approach. J Chem Phys 2013; 139:034310. [DOI: 10.1063/1.4813127] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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24
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Abstract
The broad success of optimally controlling quantum systems with external fields has been attributed to the favorable topology of the underlying control landscape, where the landscape is the physical observable as a function of the controls. The control landscape can be shown to contain no suboptimal trapping extrema upon satisfaction of reasonable physical assumptions, but this topological analysis does not hold when significant constraints are placed on the control resources. This work employs simulations to explore the topology and features of the control landscape for pure-state population transfer with a constrained class of control fields. The fields are parameterized in terms of a set of uniformly spaced spectral frequencies, with the associated phases acting as the controls. This restricted family of fields provides a simple illustration for assessing the impact of constraints upon seeking optimal control. Optimization results reveal that the minimum number of phase controls necessary to assure a high yield in the target state has a special dependence on the number of accessible energy levels in the quantum system, revealed from an analysis of the first- and second-order variation of the yield with respect to the controls. When an insufficient number of controls and/or a weak control fluence are employed, trapping extrema and saddle points are observed on the landscape. When the control resources are sufficiently flexible, solutions producing the globally maximal yield are found to form connected "level sets" of continuously variable control fields that preserve the yield. These optimal yield level sets are found to shrink to isolated points on the top of the landscape as the control field fluence is decreased, and further reduction of the fluence turns these points into suboptimal trapping extrema on the landscape. Although constrained control fields can come in many forms beyond the cases explored here, the behavior found in this paper is illustrative of the impacts that constraints can introduce.
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Affiliation(s)
- Katharine W Moore
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
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25
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Paramonov GK, Kühn O. State-Selective Vibrational Excitation and Dissociation of H2+ by Strong Infrared Laser Pulses: Below-Resonant versus Resonant Laser Fields and Electron–Field Following. J Phys Chem A 2012; 116:11388-97. [DOI: 10.1021/jp3060679] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
| | - Oliver Kühn
- Institut für Physik, Universität Rostock, D-18051 Rostock, Germany
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26
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Rabitz H, Ho TS, Long R, Wu R, Brif C. Comment on "Are there traps in quantum control landscapes?". PHYSICAL REVIEW LETTERS 2012; 108:198901-198902. [PMID: 23003098 DOI: 10.1103/physrevlett.108.198901] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Indexed: 06/01/2023]
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27
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Abstract
Controlling dynamical processes at the atomic and molecular scales with laser radiation has been a long-standing dream. The Faraday Discussion presented a cross section of the current experimental and theoretical advances as well as the challenges for the field. This paper summarizes the current status of controlling quantum dynamics phenomena and provides a perspective on the future.
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Affiliation(s)
- Herschel Rabitz
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
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28
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Feng X, Pechen A, Jha A, Wu R, Rabitz H. Global optimality of fitness landscapes in evolution. Chem Sci 2012. [DOI: 10.1039/c1sc00648g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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29
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Kinzel D, Marquetand P, González L. Stark Control of a Chiral Fluoroethylene Derivative. J Phys Chem A 2011; 116:2743-9. [DOI: 10.1021/jp207947x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Philipp Marquetand
- Institute of Theoretical Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
| | - Leticia González
- Institute of Theoretical Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
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30
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Use of the Gerchberg–Saxton algorithm in optimal coherent anti-Stokes Raman spectroscopy. Anal Bioanal Chem 2011; 402:423-8. [DOI: 10.1007/s00216-011-5348-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 08/16/2011] [Accepted: 08/17/2011] [Indexed: 10/17/2022]
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31
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Pechen AN, Tannor DJ. Are there traps in quantum control landscapes? PHYSICAL REVIEW LETTERS 2011; 106:120402. [PMID: 21517285 DOI: 10.1103/physrevlett.106.120402] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Indexed: 05/30/2023]
Abstract
There has been great interest in recent years in quantum control landscapes. Given an objective J that depends on a control field ε the dynamical landscape is defined by the properties of the Hessian δ²J/δε² at the critical points δJ/δε=0. We show that contrary to recent claims in the literature the dynamical control landscape can exhibit trapping behavior due to the existence of special critical points and illustrate this finding with an example of a 3-level Λ system. This observation can have profound implications for both theoretical and experimental quantum control studies.
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Affiliation(s)
- Alexander N Pechen
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel
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32
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Saha R, Batista VS. Tunneling under Coherent Control by Sequences of Unitary Pulses. J Phys Chem B 2011; 115:5234-42. [DOI: 10.1021/jp108331x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rajdeep Saha
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
| | - Victor S. Batista
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
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33
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Borneman TW, Hürlimann MD, Cory DG. Application of optimal control to CPMG refocusing pulse design. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 207:220-233. [PMID: 20933448 DOI: 10.1016/j.jmr.2010.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Revised: 08/30/2010] [Accepted: 09/03/2010] [Indexed: 05/30/2023]
Abstract
We apply optimal control theory (OCT) to the design of refocusing pulses suitable for the CPMG sequence that are robust over a wide range of B(0) and B(1) offsets. We also introduce a model, based on recent progress in the analysis of unitary dynamics in the field of quantum information processing (QIP), that describes the multiple refocusing dynamics of the CPMG sequence as a dephasing Pauli channel. This model provides a compact characterization of the consequences and severity of residual pulse errors. We illustrate the methods by considering a specific example of designing and analyzing broadband OCT refocusing pulses of length 10t(180) that are constrained by the maximum instantaneous pulse power. We show that with this refocusing pulse, the CPMG sequence can refocus over 98% of magnetization for resonance offsets up to 3.2 times the maximum RF amplitude, even in the presence of ±10% RF inhomogeneity.
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Affiliation(s)
- Troy W Borneman
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
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34
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Ruetzel S, Stolzenberger C, Fechner S, Dimler F, Brixner T, Tannor DJ. Molecular quantum control landscapes in von Neumann time-frequency phase space. J Chem Phys 2010; 133:164510. [DOI: 10.1063/1.3495950] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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35
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Sarma M, Adhikari S, Mishra M. Laser assisted control of selective bond dissociation in HOD–some mechanistic insights. Mol Phys 2010. [DOI: 10.1080/00268970802708934] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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36
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Control of chemical reactions using external electric fields: The case of the LiNC⇌LiCN isomerization. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.07.057] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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37
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Cao J, Silbey RJ. Optimization of exciton trapping in energy transfer processes. J Phys Chem A 2010; 113:13825-38. [PMID: 19929005 DOI: 10.1021/jp9032589] [Citation(s) in RCA: 201] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this paper, we establish optimal conditions for maximal energy transfer efficiency using solutions for multilevel systems and interpret these analytical solutions with more intuitive kinetic networks resulting from a systematic mapping procedure. The mapping procedure defines an effective hopping rate as the leading order picture and nonlocal kinetic couplings as the quantum correction, hence leading to a rigorous separation of thermal hopping and coherent transfer useful for visualizing pathway connectivity and interference in quantum networks. As a result of these calculations, the dissipative effects of the surrounding environments can be optimized to yield the maximal efficiency, and modulation of the efficiency can be achieved using the cumulative quantum phase along any closed loops. The optimal coupling of the system and its environments is interpreted with the generic mechanisms: (i) balancing localized trapping and delocalized coherence, (ii) reducing the effective detuning via homogeneous line-broadening, (iii) suppressing the destructive interference in nonlinear network configurations, and (iv) controlling phase modulation in closed loop configurations. Though these results are obtained for simple model systems, the physics thus derived provides insights into the working of light harvesting systems, and the approaches thus developed apply to large-scale computation.
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Affiliation(s)
- Jianshu Cao
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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38
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39
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Rego LG, Santos LF, Batista VS. Coherent Control of Quantum Dynamics with Sequences of Unitary Phase-Kick Pulses. Annu Rev Phys Chem 2009; 60:293-320. [DOI: 10.1146/annurev.physchem.040808.090409] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Coherent-optical-control schemes exploit the coherence of laser pulses to change the phases of interfering dynamical pathways and manipulate dynamical processes. These active control methods are closely related to dynamical decoupling techniques, popularized in the field of quantum information. Inspired by nuclear magnetic resonance spectroscopy, dynamical decoupling methods apply sequences of unitary operations to modify the interference phenomena responsible for the system dynamics thus also belonging to the general class of coherent-control techniques. This article reviews related developments in the fields of coherent optical control and dynamical decoupling, emphasizing the control of tunneling and decoherence in general model systems. Considering recent experimental breakthroughs in the demonstration of active control of a variety of systems, we anticipate that the reviewed coherent-control scenarios and dynamical-decoupling methods should raise significant experimental interest.
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Affiliation(s)
- Luis G.C. Rego
- Departamento de Física, Universidade Federal de Santa Catarina, Florianópolis, SC 88040-900 Brazil
| | - Lea F. Santos
- Department of Physics, Yeshiva University, New York, New York 10016
| | - Victor S. Batista
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107
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40
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Sarma M, Adhikari S, Mishra MK. An Examination of the Expectation Value Profiles for Average Stretch and Momentum in O−H and O−D Bonds of the HOD Molecule To Determine Their Role in Selective Photodissociation. J Phys Chem A 2008; 112:13302-7. [DOI: 10.1021/jp803690r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Manabendra Sarma
- Department of Chemistry, Indian Institute of Technology Bombay, Powai 400 076, India, Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781 039, India, and Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
| | - S. Adhikari
- Department of Chemistry, Indian Institute of Technology Bombay, Powai 400 076, India, Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781 039, India, and Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
| | - Manoj K. Mishra
- Department of Chemistry, Indian Institute of Technology Bombay, Powai 400 076, India, Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781 039, India, and Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
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41
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Marquetand P, Nuernberger P, Brixner T, Engel V. Molecular dump processes induced by chirped laser pulses. J Chem Phys 2008; 129:074303. [DOI: 10.1063/1.2960581] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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42
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Sarma M, Mishra MK. Role of Photolysis Frequency in Enhanced Selectivity and Yield for Controlled Bond Breaking in HOD. J Phys Chem A 2008; 112:4895-905. [DOI: 10.1021/jp711984t] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Manabendra Sarma
- Department of Chemistry, Indian Institute of Technology, Bombay, Powai 400076, India
| | - Manoj K. Mishra
- Department of Chemistry, Indian Institute of Technology, Bombay, Powai 400076, India
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43
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Sethi A, Keshavamurthy S. Bichromatically driven double well: Parametric perspective of the strong field control landscape reveals the influence of chaotic states. J Chem Phys 2008; 128:164117. [DOI: 10.1063/1.2907861] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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