1
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Ding YK, Zhang ZY, Liu JM. Simulation of quantum walks on a circle with polar molecules via optimal control. J Chem Phys 2023; 159:204303. [PMID: 38010330 DOI: 10.1063/5.0174472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 11/05/2023] [Indexed: 11/29/2023] Open
Abstract
Quantum walks are the quantum counterpart of classical random walks and have various applications in quantum information science. Polar molecules have rich internal energy structure and long coherence time and thus are considered as a promising candidate for quantum information processing. In this paper, we propose a theoretical scheme for implementing discrete-time quantum walks on a circle with dipole-dipole coupled SrO molecules. The states of the walker and the coin are encoded in the pendular states of polar molecules induced by an external electric field. We design the optimal microwave pulses for implementing quantum walks on a four-node circle and a three-node circle by multi-target optimal control theory. To reduce the accumulation of decoherence and improve the fidelity, we successfully realize a step of quantum walk with only one optimal pulse. Moreover, we also encode the walker into a three-level molecular qutrit and a four-level molecular ququart and design the corresponding optimal pulses for quantum walks, which can reduce the number of molecules used. It is found that all the quantum walks on a circle in our scheme can be achieved via optimal control fields with high fidelities. Our results could shed some light on the implementation of discrete-time quantum walks and high-dimensional quantum information processing with polar molecules.
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Affiliation(s)
- Yi-Kai Ding
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Zuo-Yuan Zhang
- School of Physical Science and Technology, Yangzhou University, Yangzhou 225009, China
| | - Jin-Ming Liu
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
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2
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Dimitriev OP. Dynamics of Excitons in Conjugated Molecules and Organic Semiconductor Systems. Chem Rev 2022; 122:8487-8593. [PMID: 35298145 DOI: 10.1021/acs.chemrev.1c00648] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The exciton, an excited electron-hole pair bound by Coulomb attraction, plays a key role in photophysics of organic molecules and drives practically important phenomena such as photoinduced mechanical motions of a molecule, photochemical conversions, energy transfer, generation of free charge carriers, etc. Its behavior in extended π-conjugated molecules and disordered organic films is very different and very rich compared with exciton behavior in inorganic semiconductor crystals. Due to the high degree of variability of organic systems themselves, the exciton not only exerts changes on molecules that carry it but undergoes its own changes during all phases of its lifetime, that is, birth, conversion and transport, and decay. The goal of this review is to give a systematic and comprehensive view on exciton behavior in π-conjugated molecules and molecular assemblies at all phases of exciton evolution with emphasis on rates typical for this dynamic picture and various consequences of the above dynamics. To uncover the rich variety of exciton behavior, details of exciton formation, exciton transport, exciton energy conversion, direct and reverse intersystem crossing, and radiative and nonradiative decay are considered in different systems, where these processes lead to or are influenced by static and dynamic disorder, charge distribution symmetry breaking, photoinduced reactions, electron and proton transfer, structural rearrangements, exciton coupling with vibrations and intermediate particles, and exciton dissociation and annihilation as well.
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Affiliation(s)
- Oleg P Dimitriev
- V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, pr. Nauki 41, Kyiv 03028, Ukraine
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3
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Zhang ZY, Liu JM, Hu Z, Wang Y. Implementation of three-qubit quantum computation with pendular states of polar molecules by optimal control. J Chem Phys 2020; 152:044303. [PMID: 32007056 DOI: 10.1063/1.5139688] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Ultracold polar molecules have been considered as the possible candidates for quantum information processing due to their long coherence time and strong dipole-dipole interaction. In this paper, we consider three coupled polar molecules arranged in a linear chain and trapped in an electric field with gradient. By employing the pendular states of polar molecules as qubits, we successfully realize three-qubit quantum gates and quantum algorithms via the multi-target optimal control theory. Explicitly speaking, through the designs of the optimal laser pulses with multiple iterations, the triqubit Toffoli gate, the triqubit quantum adders, and the triqubit quantum Fourier transform can be achieved in only one operational step with high fidelities and large transition probabilities. Moreover, by combining the optimized Hadamard, oracle, and diffusion gate pulses, we simulate the Grover algorithm in the three-dipole system and show that the algorithm can perform well for search problems. In addition, the behaviors of the fidelity and the average transition probability with respect to iteration numbers are compared and analyzed for each gate pulse. Our findings could pave the way toward scalability for molecular quantum computing based on the pendular states and could be extended to implement multi-particle gate operation in the molecular system.
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Affiliation(s)
- Zuo-Yuan Zhang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
| | - Jin-Ming Liu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
| | - Zhengfeng Hu
- The Key Laboratory of Quantum Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Yuzhu Wang
- The Key Laboratory of Quantum Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
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4
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Castellanos MA, Dodin A, Willard AP. On the design of molecular excitonic circuits for quantum computing: the universal quantum gates. Phys Chem Chem Phys 2020; 22:3048-3057. [DOI: 10.1039/c9cp05625d] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
This manuscript presents a strategy for controlling the transformation of excitonic states through the design of circuits made up of coupled organic dye molecules.
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Affiliation(s)
| | - Amro Dodin
- Department of Chemistry
- Massachusetts Institute of Technology
- Cambridge
- USA
| | - Adam P. Willard
- Department of Chemistry
- Massachusetts Institute of Technology
- Cambridge
- USA
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5
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Zhang ZY, Liu JM, Hu Z, Wang Y. Optical control of entanglement and coherence for polar molecules in pendular states. OPTICS EXPRESS 2019; 27:26588-26599. [PMID: 31674537 DOI: 10.1364/oe.27.026588] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 08/15/2019] [Indexed: 06/10/2023]
Abstract
Quantum entanglement and coherence are both essential physical resources in quantum theory. Cold polar molecules have long coherence time and strong dipole-dipole interaction and thus have been suggested as a platform for quantum information processing. In this paper, we employ the pendular states of the polar molecules trapped in static electric fields as the qubits, and put forward several theoretical schemes to generate the entanglement and coherence for two coupled dipoles by using optimal control theory. Through the designs of appropriate laser pulses, the transitions from the ground state to the Bell state and maximally coherent state can be realized with high fidelities 0.9906 and 0.9943 in the two-dipole system, respectively. Meanwhile, we show that the degrees of entanglement and coherence between the two pendular qubits are effectively enhanced with the help of optimized control fields. Furthermore, our schemes are generalized to the preparation of the Hardy state and even to the creation of arbitrary two-qubit states. Our findings can shed some light on the implementation of quantum information tasks with the molecular pendular states.
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6
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Yu H, Ho TS, Rabitz H. Optimal control of orientation and entanglement for two dipole–dipole coupled quantum planar rotors. Phys Chem Chem Phys 2018; 20:13008-13029. [DOI: 10.1039/c8cp00231b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Optimal control simulations are performed for orientation and entanglement of two dipole–dipole coupled identical quantum rotors.
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Affiliation(s)
- Hongling Yu
- State Key Laboratory of Precision
- East China Normal University
- Shanghai 200062
- China
- Department of Chemistry
| | - Tak-San Ho
- Department of Chemistry
- Princeton University
- Princeton
- USA
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7
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Faust C, Jones J, Huennekens J, Field RW. Experimental studies of the NaCs 12(0 +) [7 1Σ +] state: Spin-orbit and non-adiabatic interactions and quantum interference in the 12(0 +) [7 1Σ +] and 11(0 +) [5 3Π 0] emission spectra. J Chem Phys 2017; 146:104302. [PMID: 28298109 DOI: 10.1063/1.4976630] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
We present results from experimental studies of the 11(0+) and 12(0+) electronic states of the NaCs molecule. An optical-optical double resonance method is used to obtain Doppler-free excitation spectra. Selected data from the 11(0+) and 12(0+) high-lying electronic states are used to obtain Rydberg-Klein-Rees and Inverse Perturbation Approach potential energy curves. Interactions between these two electronic states are evident in the patterns observed in the bound-bound and bound-free fluorescence spectra. A model, based on two separate interaction mechanisms, is presented to describe how the wavefunctions of the two states mix. The electronic parts of the wavefunctions interact via spin-orbit coupling, while the individual rotation-vibration levels interact via a second mechanism, which is likely to be non-adiabatic coupling. A modified version of the BCONT program was used to simulate resolved fluorescence from both upper states. Parameters of the model that describe the two interaction mechanisms were varied until simulations were able to adequately reproduce experimental spectra.
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Affiliation(s)
- C Faust
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, Pennsylvania 18015, USA
| | - J Jones
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, Pennsylvania 18015, USA
| | - J Huennekens
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, Pennsylvania 18015, USADepartment of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - R W Field
- Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, Pennsylvania 18015, USADepartment of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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8
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Tyagi A, Maan A, Ahlawat DS, Prasad V. Effect of aligning pulse train on the orientation and alignment of a molecule in presence of orienting pulse. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 173:13-18. [PMID: 27588726 DOI: 10.1016/j.saa.2016.08.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 08/19/2016] [Accepted: 08/19/2016] [Indexed: 06/06/2023]
Abstract
Field-free molecular alignment is studied theoretically in presence of orienting laser pulse and a delayed Infrared laser (IRL) pulse train. The pulse shapes taken are sine square (sin2) and square. The degree of alignment can be significantly enhanced by the combination of orienting pulse and IRL pulse train compared with only IRL pulse train. Special emphasis is laid on time delay between orienting and aligning pulse, the width and shape of the pulse train. By adjusting the time delay, width and intensity of coupling laser one can suppress a population of particular state while simultaneously enhancing the population of desired states.
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Affiliation(s)
- Ashish Tyagi
- Department of Physics, Swami Shradhanand College, University of Delhi, Delhi 110036, India.
| | - Anjali Maan
- Department of Physics, Chaudhary Devi Lal University, Sirsa 125055, Haryana, India.
| | | | - Vinod Prasad
- Department of Physics, Swami Shradhanand College, University of Delhi, Delhi 110036, India.
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9
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Tyagi A, Silotia P, Maan A, Prasad V. Adsorbed molecules in external fields: Effect of confining potential. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2016; 169:238-245. [PMID: 27387127 DOI: 10.1016/j.saa.2016.04.052] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Revised: 04/25/2016] [Accepted: 04/27/2016] [Indexed: 06/06/2023]
Abstract
We study the rotational excitation of a molecule adsorbed on a surface. As is well known the interaction potential between the surface and the molecule can be modeled in number of ways, depending on the molecular structure and the geometry under which the molecule is being adsorbed by the surface. We explore the effect of change of confining potential on the excitation, which is largely controlled by the static electric fields and continuous wave laser fields. We focus on dipolar molecules and hence we restrict ourselves to the first order interaction in field-molecule interaction potential either through permanent dipole moment or/and the molecular polarizability parameter. It is shown that confining potential shapes, strength of the confinement, strongly affect the excitation. We compare our results for different confining potentials.
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Affiliation(s)
- Ashish Tyagi
- Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India.
| | - Poonam Silotia
- Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India.
| | - Anjali Maan
- Department of Physics, Pt. N. R. S. G. C., Maharishi Dayanand University, Rohtak, Haryana, India.
| | - Vinod Prasad
- Department of Physics, Swami Shraddhanand College, University of Delhi, Delhi 110036, India.
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10
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Zhang Y, Kersell H, Stefak R, Echeverria J, Iancu V, Perera UGE, Li Y, Deshpande A, Braun KF, Joachim C, Rapenne G, Hla SW. Simultaneous and coordinated rotational switching of all molecular rotors in a network. NATURE NANOTECHNOLOGY 2016; 11:706-712. [PMID: 27159740 DOI: 10.1038/nnano.2016.69] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Accepted: 03/31/2016] [Indexed: 06/05/2023]
Abstract
A range of artificial molecular systems has been created that can exhibit controlled linear and rotational motion. In the further development of such systems, a key step is the addition of communication between molecules in a network. Here, we show that a two-dimensional array of dipolar molecular rotors can undergo simultaneous rotational switching when applying an electric field from the tip of a scanning tunnelling microscope. Several hundred rotors made from porphyrin-based double-decker complexes can be simultaneously rotated when in a hexagonal rotor network on a Cu(111) surface by applying biases above 1 V at 80 K. The phenomenon is observed only in a hexagonal rotor network due to the degeneracy of the ground-state dipole rotational energy barrier of the system. Defects are essential to increase electric torque on the rotor network and to stabilize the switched rotor domains. At low biases and low initial rotator angles, slight reorientations of individual rotors can occur, resulting in the rotator arms pointing in different directions. Analysis reveals that the rotator arm directions are not random, but are coordinated to minimize energy via crosstalk among the rotors through dipolar interactions.
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Affiliation(s)
- Y Zhang
- Physics and Astronomy Department, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701, USA
| | - H Kersell
- Physics and Astronomy Department, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701, USA
| | - R Stefak
- CEMES, CNRS, 29 rue J. Marvig, 31055 Toulouse, France
| | - J Echeverria
- CEMES, CNRS, 29 rue J. Marvig, 31055 Toulouse, France
| | - V Iancu
- Physics and Astronomy Department, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701, USA
| | - U G E Perera
- Physics and Astronomy Department, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701, USA
| | - Y Li
- Physics and Astronomy Department, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701, USA
| | - A Deshpande
- Physics and Astronomy Department, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701, USA
| | - K-F Braun
- Physics and Astronomy Department, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701, USA
| | - C Joachim
- CEMES, CNRS, 29 rue J. Marvig, 31055 Toulouse, France
| | - G Rapenne
- CEMES, CNRS, 29 rue J. Marvig, 31055 Toulouse, France
- Universite' de Toulouse, UPS, 118 route de Narbonne, 31062 Toulouse, France
| | - S-W Hla
- Physics and Astronomy Department, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701, USA
- Center for Nanoscale Materials, Nanoscience and Technology Division, Argonne National Laboratory, Illinois 60439, USA
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11
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McKemmish LK, McKenzie RH, Hush NS, Reimers JR. Electron-vibration entanglement in the Born-Oppenheimer description of chemical reactions and spectroscopy. Phys Chem Chem Phys 2016. [PMID: 26204101 DOI: 10.1039/c5cp02239h] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Entanglement is sometimes regarded as the quintessential measure of the quantum nature of a system and its significance for the understanding of coupled electronic and vibrational motions in molecules has been conjectured. Previously, we considered the entanglement developed in a spatially localized diabatic basis representation of the electronic states, considering design rules for qubits in a low-temperature chemical quantum computer. We extend this to consider the entanglement developed during high-energy processes. We also consider the entanglement developed using adiabatic electronic basis, providing a novel way for interpreting effects of the breakdown of the Born-Oppenheimer (BO) approximation. We consider: (i) BO entanglement in the ground-state wavefunction relevant to equilibrium thermodynamics, (ii) BO entanglement associated with low-energy wavefunctions relevant to infrared and tunneling spectroscopies, (iii) BO entanglement in high-energy eigenfunctions relevant to chemical reaction processes, and (iv) BO entanglement developed during reactive wavepacket dynamics. A two-state single-mode diabatic model descriptive of a wide range of chemical phenomena is used for this purpose. The entanglement developed by BO breakdown correlates simply with the diameter of the cusp introduced by the BO approximation, and a hierarchy appears between the various BO-breakdown correction terms, with the first-derivative correction being more important than the second-derivative correction which is more important than the diagonal correction. This simplicity is in contrast to the complexity of BO-breakdown effects on thermodynamic, spectroscopic, and kinetic properties. Further, processes poorly treated at the BO level that appear adequately treated using the Born-Huang adiabatic approximation are found to have properties that can only be described using a non-adiabatic description. For the entanglement developed between diabatic electronic states and the nuclear motion, qualitatively differently behavior is found compared to traditional properties of the density matrix and hence entanglement provides new information about system properties. For chemical reactions, this type of entanglement simply builds up as the transition-state region is crossed. It is robust to small changes in parameter values and is therefore more attractive for making quantum qubits than is the related fragile ground-state entanglement, provided that coherent motion at the transition state can be sustained.
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Affiliation(s)
- Laura K McKemmish
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
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12
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Santos L, Justum Y, Vaeck N, Desouter-Lecomte M. Simulation of the elementary evolution operator with the motional states of an ion in an anharmonic trap. J Chem Phys 2015; 142:134304. [DOI: 10.1063/1.4916355] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ludovic Santos
- Laboratoire de Chimie Quantique et Photophysique, CP 160/09 Université Libre de Bruxelles, B-1050 Brussels, Belgium
| | - Yves Justum
- Laboratoire de Chimie Physique, UMR 8000 and CNRS, Université Paris-Sud, F-91405 Orsay, France
| | - Nathalie Vaeck
- Laboratoire de Chimie Quantique et Photophysique, CP 160/09 Université Libre de Bruxelles, B-1050 Brussels, Belgium
| | - M. Desouter-Lecomte
- Laboratoire de Chimie Physique, UMR 8000 and CNRS, Université Paris-Sud, F-91405 Orsay, France
- Département de Chimie, Université de Liège, Bât B6c, Sart Tilman B-4000, Liège, Belgium
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13
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Shyshlov D, Berrios E, Gruebele M, Babikov D. On readout of vibrational qubits using quantum beats. J Chem Phys 2014; 141:224306. [PMID: 25494748 DOI: 10.1063/1.4903055] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Dmytro Shyshlov
- Chemistry Department, Marquette University, Milwaukee, Wisconsin 53201, USA
| | - Eduardo Berrios
- Department of Chemistry, Department of Physics and Center for Biophysics and Computational Biology, University of Illinois, Urbana, Illinois 61801, USA
| | - Martin Gruebele
- Department of Chemistry, Department of Physics and Center for Biophysics and Computational Biology, University of Illinois, Urbana, Illinois 61801, USA
| | - Dmitri Babikov
- Chemistry Department, Marquette University, Milwaukee, Wisconsin 53201, USA
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14
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Jaouadi A, Barrez E, Justum Y, Desouter-Lecomte M. Quantum gates in hyperfine levels of ultracold alkali dimers by revisiting constrained-phase optimal control design. J Chem Phys 2013; 139:014310. [PMID: 23822306 DOI: 10.1063/1.4812317] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We simulate the implementation of a 3-qubit quantum Fourier transform gate in the hyperfine levels of ultracold polar alkali dimers in their first two lowest rotational levels. The chosen dimer is (41)K(87)Rb supposed to be trapped in an optical lattice. The hyperfine levels are split by a static magnetic field. The pulses operating in the microwave domain are obtained by optimal control theory. We revisit the problem of phase control in information processing. We compare the efficiency of two optimal fields. The first one is obtained from a functional based on the average of the transition probabilities for each computational basis state but constrained by a supplementary transformation to enforce phase alignment. The second is obtained from a functional constructed on the phase sensitive fidelity involving the sum of the transition amplitudes without any supplementary constrain.
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Affiliation(s)
- A Jaouadi
- Laboratoire de Chimie Physique, UMR 8000 and CNRS, Université Paris-Sud, Orsay, France
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15
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Zhu J, Kais S, Wei Q, Herschbach D, Friedrich B. Implementation of quantum logic gates using polar molecules in pendular states. J Chem Phys 2013; 138:024104. [DOI: 10.1063/1.4774058] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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Zaari RR, Brown A. Effect of laser pulse shaping parameters on the fidelity of quantum logic gates. J Chem Phys 2012; 137:104306. [PMID: 22979858 DOI: 10.1063/1.4747703] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The effect of varying parameters specific to laser pulse shaping instruments on resulting fidelities for the ACNOT(1), NOT(2), and Hadamard(2) quantum logic gates are studied for the diatomic molecule (12)C(16)O. These parameters include varying the frequency resolution, adjusting the number of frequency components and also varying the amplitude and phase at each frequency component. A time domain analytic form of the original discretized frequency domain laser pulse function is derived, providing a useful means to infer the resulting pulse shape through variations to the aforementioned parameters. We show that amplitude variation at each frequency component is a crucial requirement for optimal laser pulse shaping, whereas phase variation provides minimal contribution. We also show that high fidelity laser pulses are dependent upon the frequency resolution and increasing the number of frequency components provides only a small incremental improvement to quantum gate fidelity. Analysis through use of the pulse area theorem confirms the resulting population dynamics for one or two frequency high fidelity laser pulses and implies similar dynamics for more complex laser pulse shapes. The ability to produce high fidelity laser pulses that provide both population control and global phase alignment is attributed greatly to the natural evolution phase alignment of the qubits involved within the quantum logic gate operation.
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Affiliation(s)
- Ryan R Zaari
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
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17
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Ashman S, McGeehan B, Wolfe CM, Faust C, Richter K, Jones J, Hickman AP, Huennekens J. Experimental studies of the NaCs 5(3)Π0 and 1(a)3Σ+ states. J Chem Phys 2012; 136:114313. [PMID: 22443770 DOI: 10.1063/1.3689388] [Citation(s) in RCA: 11] [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 report high resolution measurements of 372 NaCs 5(3)Π(0)(v, J) ro-vibrational level energies in the range 0 ≤ v ≤ 22. The data have been used to construct NaCs 5(3)Π(0) potential energy curves using the Rydberg-Klein-Rees and inverted perturbation approximation methods. Bound-free 5(3)Π(0)(v, J) → 1(a)(3)Σ(+) emission has also been measured, and is used to determine the repulsive wall of the 1(a)(3)Σ(+) state and the 5(3)Π(0) → 1(a)(3)Σ(+) relative transition dipole moment function. Hyperfine structure in the 5(3)Π(0) state has not been observed in this experiment. This null result is explained using a simple vector coupling model.
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Affiliation(s)
- S Ashman
- Department of Physics, 16 Memorial Dr. East, Lehigh University, Bethlehem, Pennsylvania 18015, USA
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18
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Wei Q, Kais S, Friedrich B, Herschbach D. Entanglement of polar symmetric top molecules as candidate qubits. J Chem Phys 2011; 135:154102. [DOI: 10.1063/1.3649949] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Qi Wei
- Department of Physics, Texas A & M University, College Station, Texas 77843, USA
| | - Sabre Kais
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
| | - Bretislav Friedrich
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Dudley Herschbach
- Department of Physics, Texas A & M University, College Station, Texas 77843, USA
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19
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Zaari RR, Brown A. Effect of diatomic molecular properties on binary laser pulse optimizations of quantum gate operations. J Chem Phys 2011; 135:044317. [DOI: 10.1063/1.3617248] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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20
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The operations of quantum logic gates with pure and mixed initial states. J Chem Phys 2011; 134:134103. [DOI: 10.1063/1.3571597] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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21
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Mishima K, Yamashita K. Free-time and fixed end-point multi-target optimal control theory: Application to quantum computing. Chem Phys 2011. [DOI: 10.1016/j.chemphys.2010.10.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Pellegrini P, Vranckx S, Desouter-Lecomte M. Implementing quantum algorithms in hyperfine levels of ultracold polar molecules by optimal control. Phys Chem Chem Phys 2011; 13:18864-71. [DOI: 10.1039/c1cp21184f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Bomble L, Lauvergnat D, Remacle F, Desouter-Lecomte M. Controlled full adder-subtractor by vibrational computing. Phys Chem Chem Phys 2010; 12:15628-35. [PMID: 20661490 DOI: 10.1039/c003687k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The implementation of a quantum-controlled full adder-subtractor of two binary digits and of a "carry in" or a "borrow in" is simulated by encoding four qubits in the vibrational eigenstates of a tetra-atomic molecule (trans-HONO). The laser field of the gate is computed using optimal control theory by treating dynamics in full dimensionality. A controlled qubit enforces the addition or the subtraction. The global unitary transformation that connects the inputs to the outputs is driven by a single laser pulse. This decreases the duration of the operation and allows for a better use of the optical resources and for an improvement of the fidelity (>97%). Initialization and reading out are discussed. The timescale of the sequence initialization, gate and read out is<100 ps.
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Affiliation(s)
- Laëtitia Bomble
- Laboratoire de Chimie Physique, Université de Paris-Sud, UMR8000, Orsay, F-91405, France
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