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Castaldo D, Rosa M, Corni S. Fast-forwarding molecular ground state preparation with optimal control on analog quantum simulators. J Chem Phys 2024; 161:014105. [PMID: 38949276 DOI: 10.1063/5.0204618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 06/10/2024] [Indexed: 07/02/2024] Open
Abstract
We show that optimal control of the electron dynamics is able to prepare molecular ground states, within chemical accuracy, with evolution times approaching the bounds imposed by quantum mechanics. We propose a specific parameterization of the molecular evolution only in terms of interaction already present in the molecular Hamiltonian. Thus, the proposed method solely utilizes quantum simulation routines, retaining their favorable scalings. Due to the intimate relationships between variational quantum algorithms and optimal control, we compare, when possible, our results with state-of-the-art methods in the literature. We found that the number of parameters needed to reach chemical accuracy and algorithmic scaling is in line with compact adaptive strategies to build variational Ansätze. The algorithm, which is also suitable for quantum simulators, is implemented by emulating a digital quantum processor (up to 16 qubits) and tested on different molecules and geometries spanning different degrees of electron correlation.
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Affiliation(s)
- Davide Castaldo
- Università degli Studi di Padova, Dipartimento di Scienze Chimiche, via Marzolo 1, 35131 Padova, Italy
| | - Marta Rosa
- Università degli Studi di Padova, Dipartimento di Scienze Chimiche, via Marzolo 1, 35131 Padova, Italy
| | - Stefano Corni
- Università degli Studi di Padova, Dipartimento di Scienze Chimiche, via Marzolo 1, 35131 Padova, Italy
- Padua Quantum Technologies Research Center, Università di Padova, Padova, Italy
- Istituto Nanoscienze-CNR, via Campi 213/A, 41125 Modena, Italy
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2
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Kosloff R. Quantum Molecular Devices. ACS PHYSICAL CHEMISTRY AU 2024; 4:226-231. [PMID: 38800727 PMCID: PMC11117685 DOI: 10.1021/acsphyschemau.3c00077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 02/01/2024] [Accepted: 02/07/2024] [Indexed: 05/29/2024]
Abstract
Miniaturization has been the driving force in contemporary technologies. However, two main obstacles limit further progress: additional reduction in size has reached its quantum limit, and lithography has reached its threshold. Future progress requires tackling three challenges: chemical synthesis of a complete device, active cooling for exploiting quantum characteristics, and quantum coherent control for operation. Chemical synthesis replaces the current top-bottom approach to manufacturing with bottom-up synthesis from elementary building blocks. New ultracold synthetic methods should be developed. An additional challenge is the active cooling of molecules, where the bottleneck is entropy removal. Notably, the current solution, namely, diffusion, is too slow. A coherent approach offers a possible solution; specifically, quantum coherent control is the method of choice for manipulating ultracold matter. Finally, the many degrees of freedom of molecules should be an asset that allows the design and implementation of complex tasks such as sensing communication and computing.
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Affiliation(s)
- Ronnie Kosloff
- Institute of Chemistry, Hebrew
University of Jerusalem, Jerusalem 9190401, Israel
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3
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Morzhin OV, Pechen AN. Control of the von Neumann Entropy for an Open Two-Qubit System Using Coherent and Incoherent Drives. ENTROPY (BASEL, SWITZERLAND) 2023; 26:36. [PMID: 38248162 PMCID: PMC10814796 DOI: 10.3390/e26010036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 12/20/2023] [Accepted: 12/23/2023] [Indexed: 01/23/2024]
Abstract
This article is devoted to developing an approach for manipulating the von Neumann entropy S(ρ(t)) of an open two-qubit system with coherent control and incoherent control inducing time-dependent decoherence rates. The following goals are considered: (a) minimizing or maximizing the final entropy S(ρ(T)); (b) steering S(ρ(T)) to a given target value; (c) steering S(ρ(T)) to a target value and satisfying the pointwise state constraint S(ρ(t))≤S¯ for a given S¯; (d) keeping S(ρ(t)) constant at a given time interval. Under the Markovian dynamics determined by a Gorini-Kossakowski-Sudarshan-Lindblad type master equation, which contains coherent and incoherent controls, one- and two-step gradient projection methods and genetic algorithm have been adapted, taking into account the specifics of the objective functionals. The corresponding numerical results are provided and discussed.
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Affiliation(s)
- Oleg V. Morzhin
- Department of Mathematical Methods for Quantum Technologies & Steklov International Mathematical Center, Steklov Mathematical Institute of Russian Academy of Sciences, Gubkina Str. 9, 119991 Moscow, Russia
- Quantum Engineering Research and Education Center, University of Science and Technology MISIS, Leninskii Prosp. 4, 119991 Moscow, Russia
| | - Alexander N. Pechen
- Department of Mathematical Methods for Quantum Technologies & Steklov International Mathematical Center, Steklov Mathematical Institute of Russian Academy of Sciences, Gubkina Str. 9, 119991 Moscow, Russia
- Quantum Engineering Research and Education Center, University of Science and Technology MISIS, Leninskii Prosp. 4, 119991 Moscow, Russia
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4
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Kallush S, Dann R, Kosloff R. Controlling the uncontrollable: Quantum control of open-system dynamics. SCIENCE ADVANCES 2022; 8:eadd0828. [PMID: 36322661 PMCID: PMC9629718 DOI: 10.1126/sciadv.add0828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
Control of open quantum systems is essential for the realization of contemporary quantum science and technology. We demonstrate such control using a thermodynamically consistent framework, taking into account the fact that the drive can modify the system's interaction with the environment. Such an effect is incorporated within the dynamical equation, leading to control-dependent dissipation. This relation serves as the key element for open-system control. The control paradigm is displayed by analyzing entropy-changing state-to-state transformations, such as heating and cooling. The difficult task of controlling quantum gates is achieved for nonunitary reset maps with complete memory loss. In addition, we identify a mechanism for controlling unitary gates by actively removing entropy from the system to the environment. We demonstrate a universal set of single- and double-qubit unitary gates under dissipation.
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Affiliation(s)
- Shimshon Kallush
- Sciences Department, Holon Academic Institute of Technology, 52 Golomb Street, Holon 58102, Israel
- The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Roie Dann
- The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Ronnie Kosloff
- The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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5
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Gao Y, Wang X, Yu N, Wong BM. Harnessing deep reinforcement learning to construct time-dependent optimal fields for quantum control dynamics. Phys Chem Chem Phys 2022; 24:24012-24020. [PMID: 36128792 DOI: 10.1039/d2cp02495k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present an efficient deep reinforcement learning (DRL) approach to automatically construct time-dependent optimal control fields that enable desired transitions in dynamical chemical systems. Our DRL approach gives impressive performance in constructing optimal control fields, even for cases that are difficult to converge with existing gradient-based approaches. We provide a detailed description of the algorithms and hyperparameters as well as performance metrics for our DRL-based approach. Our results demonstrate that DRL can be employed as an effective artificial intelligence approach to efficiently and autonomously design control fields in quantum dynamical chemical systems.
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Affiliation(s)
- Yuanqi Gao
- Department of Electrical and Computer Engineering, University of California-Riverside, Riverside, CA, USA
| | - Xian Wang
- Department of Physics and Astronomy, University of California-Riverside, Riverside, CA, USA
| | - Nanpeng Yu
- Department of Electrical and Computer Engineering, University of California-Riverside, Riverside, CA, USA.
| | - Bryan M Wong
- Department of Chemical and Environmental Engineering, Materials Science and Engineering Program, Department of Chemistry, and Department of Physics and Astronomy, University of California-Riverside, Riverside, CA, USA.
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6
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Wang X, Kumar A, Shelton CR, Wong BM. Harnessing deep neural networks to solve inverse problems in quantum dynamics: machine-learned predictions of time-dependent optimal control fields. Phys Chem Chem Phys 2020; 22:22889-22899. [PMID: 32935687 DOI: 10.1039/d0cp03694c] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Inverse problems continue to garner immense interest in the physical sciences, particularly in the context of controlling desired phenomena in non-equilibrium systems. In this work, we utilize a series of deep neural networks for predicting time-dependent optimal control fields, E(t), that enable desired electronic transitions in reduced-dimensional quantum dynamical systems. To solve this inverse problem, we investigated two independent machine learning approaches: (1) a feedforward neural network for predicting the frequency and amplitude content of the power spectrum in the frequency domain (i.e., the Fourier transform of E(t)), and (2) a cross-correlation neural network approach for directly predicting E(t) in the time domain. Both of these machine learning methods give complementary approaches for probing the underlying quantum dynamics and also exhibit impressive performance in accurately predicting both the frequency and strength of the optimal control field. We provide detailed architectures and hyperparameters for these deep neural networks as well as performance metrics for each of our machine-learned models. From these results, we show that machine learning, particularly deep neural networks, can be employed as cost-effective statistical approaches for designing electromagnetic fields to enable desired transitions in these quantum dynamical systems.
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Affiliation(s)
- Xian Wang
- Department of Physics & Astronomy, University of California-Riverside, Riverside, CA 92521, USA
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7
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Abstract
A comprehensive approach to modeling open quantum systems consistent with thermodynamics is presented. The theory of open quantum systems is employed to define system bath partitions. The Markovian master equation defines an isothermal partition between the system and bath. Two methods to derive the quantum master equation are described: the weak coupling limit and the repeated collision model. The role of the eigenoperators of the free system dynamics is highlighted, in particular, for driven systems. The thermodynamical relations are pointed out. Models that lead to loss of coherence, i.e., dephasing are described. The implication of the laws of thermodynamics to simulating transport and spectroscopy is described. The indications for self-averaging in large quantum systems and thus its importance in modeling are described. Basic modeling by the surrogate Hamiltonian is described, as well as thermal boundary conditions using the repeated collision model and their use in the stochastic surrogate Hamiltonian. The problem of modeling with explicitly time dependent driving is analyzed. Finally, the use of the stochastic surrogate Hamiltonian for modeling ultrafast spectroscopy and quantum control is reviewed.
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Affiliation(s)
- Ronnie Kosloff
- The Institute of Chemistry and The Fritz Haber Centre for Theoretical Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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8
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9
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Affiliation(s)
- Christiane P. Koch
- Theoretische Physik, Universität Kassel, Heinrich-Plett-Strasse 40,
34132 Kassel, Germany
| | - Moshe Shapiro
- Department
of Chemistry, University of British Columbia, Vancouver, Canada V6T
1Z1, and Department of Chemical Physics, The Weizmann Institute, Rehovot, Israel 76100
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10
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Bomble L, Chenel A, Meier C, Desouter-Lecomte M. Local control of non-adiabatic dissociation dynamics. J Chem Phys 2011; 134:204112. [DOI: 10.1063/1.3589911] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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11
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Tomza M, Pawłowski F, Jeziorska M, Koch CP, Moszynski R. Formation of ultracold SrYb molecules in an optical lattice by photoassociation spectroscopy: theoretical prospects. Phys Chem Chem Phys 2011; 13:18893-904. [DOI: 10.1039/c1cp21196j] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Sofikitis D, Fioretti A, Weber S, Horchani R, Pichler M, Li X, Allegrini M, Chatel B, Comparat D, Pillet P. Vibrational cooling of cold molecules with optimised shaped pulses. Mol Phys 2010. [DOI: 10.1080/00268971003689899] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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13
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Viteau M, Chotia A, Sofikitis D, Allegrini M, Bouloufa N, Dulieu O, Comparat D, Pillet P. Broadband lasers to detect and cool the vibration of cold molecules. Faraday Discuss 2010; 142:257-70; discussion 319-34. [PMID: 20151547 DOI: 10.1039/b819697d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
By using broadband lasers, we demonstrate the possibilities for control of cold molecules formed via photoassociation. Firstly, we present a detection REMPI scheme (M. Viteau et al., Phys. Rev. A, 2009, 79, 021402) to systematically investigate the mechanisms of formation of ultracold Cs2 molecules in deeply bound levels of their electronic ground state X1sigma(g)+. This broadband detection scheme could be generalized to other molecular species. Then we report a vibrational cooling technique (M. Viteau et al., Science, 2008, 321, 232) through optical pumping obtained by using a shaped mode locked femtosecond laser. The broadband femtosecond laser excites the molecules electronically, leading to a redistribution of the vibrational population in the ground state via a few absorption-spontaneous emission cycles. By removing the laser frequencies corresponding to the excitation of the v = 0 level, we realize a dark state for the so-shaped femtosecond laser, leading, with the successive laser pulses, to an accumulation of the molecules in the v = 0 level, ie. a laser cooling of the vibration. The simulation of the vibrational laser cooling allows us to characterize the criteria to extend the mechanism to other molecular species (R. V. Krems, Int. Rev. Phys. Chem., 2005, 24, 99). We finally discuss the generalization of the technique to laser cooling of the rotation of the molecule.
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Affiliation(s)
- Matthieu Viteau
- Laboratoire Aimé Cotton, CNRS, Univ Paris-Sud, Bât. 505, 91405 Orsay, France
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14
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Sofikitis D, Fioretti A, Weber S, Viteau M, Chotia A, Horchani R, Allegrini M, Chatel B, Comparat D, Pillet P. Broadband Vibrational Cooling of Cold Cesium Molecules: Theory and Experiments. CHINESE J CHEM PHYS 2009. [DOI: 10.1088/1674-0068/22/02/149-156] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Local Control Theory: Recent Applications to Energy and Particle Transfer Processes in Molecules. ADVANCES IN CHEMICAL PHYSICS 2009. [DOI: 10.1002/9780470431917.ch2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2023]
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16
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Beyvers S, Saalfrank P. A hybrid local/global optimal control algorithm for dissipative systems with time-dependent targets: Formulation and application to relaxing adsorbates. J Chem Phys 2008; 128:074104. [DOI: 10.1063/1.2830709] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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17
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Wu F, Chen L, Wu S, Sun F. Thermodynamic performance of a laser cryocooler. J Chem Phys 2007; 126:204502. [PMID: 17552773 DOI: 10.1063/1.2736684] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The quantum dynamic action of a laser cooling system is analyzed by means of a simplified luminescence center model with ground state and excited state in this paper. The thermodynamic performance of a laser cryocooler is described by solving quantum master equation. The cooling load and the coefficient of performance of the cooler are obtained by using finite time thermodynamics. Some features of the system under the weak coupling and under the intense coupling conditions are discussed.
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Affiliation(s)
- Feng Wu
- Postgraduate School, Naval University of Engineering, Wuhan 430033, People's Rupublic of China
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18
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Katz G, Ratner MA, Kosloff R. Decoherence control by tracking a Hamiltonian reference molecule. PHYSICAL REVIEW LETTERS 2007; 98:203006. [PMID: 17677692 DOI: 10.1103/physrevlett.98.203006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Revised: 02/15/2007] [Indexed: 05/16/2023]
Abstract
A molecular system in contact with a bath undergoes strong decoherence processes. We examine a control scheme to minimize dissipation, while maximally retaining coherent evolution, by relating the evolution of the molecule to that of an identical freely propagating system. We seek a driving field that maximizes the projection of the open molecular system onto the freely propagated one. The evolution in time of a molecular system consisting of two nonadiabatically coupled electronic states interacting with a bath is followed. The driving control field that overcomes the decoherence is calculated. A proposition to implement the scheme in the laboratory using feedback control is suggested.
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Affiliation(s)
- Gil Katz
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA
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19
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Cheng T, Brown A. Pulse shaping for optimal control of molecular processes. J Chem Phys 2006; 124:144109. [PMID: 16626182 DOI: 10.1063/1.2187977] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In this paper, a new method is proposed to design optimized control fields with desired temporal and/or spectral properties. The method is based on penalizing the difference between an optimized field obtained from an iterative scheme and a reference field with desired temporal and/or spectral properties. Compared with the standard optimal control theory, the current method allows a simple, experimentally accessible field be found on the fly; while compared with parameter space searching optimization, the iterative nature of this method allows automatic exploration of the intrinsic mechanism of the population transfer. The method is illustrated by examing the optimal control of vibrational excitation of the Cl-O bond with both temporally and spectrally restricted pulses.
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Affiliation(s)
- Taiwang Cheng
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
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20
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Sugawara M. Quantum dynamics driven by continuous laser fields under measurements: Towards measurement-assisted quantum dynamics control. J Chem Phys 2005; 123:204115. [PMID: 16351248 DOI: 10.1063/1.2132275] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We study quantum system dynamics driven by continuous laser fields under the measurement process. In order to take into account the system transition due to the measurement, we define the superoperator which eliminates the coherence relevant to the measured quantum states. We clarify that the dynamics of the measured states is frozen in the frequent measurement limit, while the space spanned by unmeasured states is isolated from the original system. We also derive the effective Liouvillian which governs incoherent population dynamics under the condition, in which measurements are frequently applied. We apply the formulation to two-level and Lambda-type three-level systems and clarify how the quantum measurements hinder the coherent population dynamics driven by the continuous laser fields in practical examples. Analysis on the laser field amplitude dependency of the final distribution in the t-->infinity limit suggests the possibility of the measurement-assisted quantum control.
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Affiliation(s)
- M Sugawara
- Department of Fundamental Science and Technology, Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.
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21
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Meier C, Heitz MC. Laser control of vibrational excitation in carboxyhemoglobin: A quantum wave packet study. J Chem Phys 2005; 123:044504. [PMID: 16095366 DOI: 10.1063/1.1946737] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A coherent control algorithm is applied to obtain complex-shaped infrared laser pulses for the selective vibrational excitation of carbon monoxide at the active site of carbonmonoxyhemoglobin, modeled by the six-coordinated iron-porphyrin-imidazole-CO complex. The influence of the distal histidine is taken into account by an additional imidazole molecule. Density-functional theory is employed to calculate a multidimensional ground-state potential energy surface, and the vibrational dynamics as well as the laser interaction is described by quantum wave-packet calculations. At each instant in time, the optimal electric field is calculated and used for the subsequent quantum dynamics. The results presented show that the control scheme is applicable to complex systems and that it yields laser pulses with complex time-frequency structures, which, nevertheless, have a clear physical interpretation.
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Affiliation(s)
- Christoph Meier
- Laboratoire Collisions, Agrégats et Réactivité, UMR 5589, Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes, Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse, France.
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22
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Geppert D, de Vivie-Riedle R. Reaction velocity control by manipulating the momentum of a nuclear wavepacket with phase-sensitive optimal control theory. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.01.110] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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Lami A, Santoro F. Weak-field laser control of systems experiencing dissipation and decoherence. An application to the enhancement of the coherent fluorescence of the B850 ring in light harvesting complexes. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2003.11.101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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24
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Sugawara M. General formulation of locally designed coherent control theory for quantum system. J Chem Phys 2003. [DOI: 10.1063/1.1559680] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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25
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Zhu W, Rabitz H. Closed loop learning control to suppress the effects of quantum decoherence. J Chem Phys 2003. [DOI: 10.1063/1.1559484] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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26
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Abstract
Active control of chemical reactions on a microscopic (molecular) level, that is, the selective breaking or making of chemical bonds, is an old dream. However, conventional control agents used in chemical synthesis are macroscopic variables such as temperature, pressure or concentration, which gives no direct access to the quantum-mechanical reaction pathway. In quantum control, by contrast, molecular dynamics are guided with specifically designed light fields. Thus it is possible to efficiently and selectively reach user-defined reaction channels. In the last years, experimental techniques were developed by which many breakthroughs in this field were achieved. Femtosecond laser pulses are manipulated in so-called pulse shapers to generate electric field profiles which are specifically adapted to a given quantum system and control objective. The search for optimal fields is guided by an automated learning loop, which employs direct feedback from experimental output. Thereby quantum control over gas-phase as well as liquid-phase femtochemical processes has become possible. In this review, we first discuss the theoretical and experimental background for many of the recent experiments treated in the literature. Examples from our own research are then used to illustrate several fundamental and practical aspects in gas-phase as well as liquid-phase quantum control. Some additional technological applications and developments are also described, such as the automated optimization of the output from commercial femtosecond laser systems, or the control over the polarization state of light on an ultrashort timescale. The increasing number of successful implementations of adaptive learning techniques points at the great versatility of computer-guided optimization methods. The general approach to active control of light-matter interaction has also applications in many other areas of modern physics and related disciplines.
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Affiliation(s)
- Tobias Brixner
- Physikalisches Institut, Universität Würzburg Am Hubland, 97074 Würzburg, Germany
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27
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Palao JP, Kosloff R. Quantum computing by an optimal control algorithm for unitary transformations. PHYSICAL REVIEW LETTERS 2002; 89:188301. [PMID: 12398642 DOI: 10.1103/physrevlett.89.188301] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2002] [Indexed: 05/24/2023]
Abstract
Quantum computation is based on implementing selected unitary transformations representing algorithms. A generalized optimal control theory is used to find the driving field that generates a prespecified unitary transformation. The approach is independent of the physical implementation of the quantum computer and it is illustrated for one and two qubit gates in model molecular systems, where only part of the Hilbert space is used for computation.
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Affiliation(s)
- José P Palao
- Department of Physical Chemistry and the Fritz Haber Research Center for Molecular Dynamics, Hebrew University, Jerusalem 91904, Israel
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28
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Lami A, Santoro F. Stable laser control of complex multilevel systems using a weak-intensity multicolor gaussian pulse. Chem Phys 2002. [DOI: 10.1016/s0301-0104(02)00330-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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