Co-reporter:Qi Wei, Pingxiao Wang, Sabre Kais, Dudley Herschbach
Chemical Physics Letters 2017 Volume 683(Volume 683) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.cplett.2017.02.017
•Analysis of a unique laser experiment producing unprecedented acceleration of neutral atoms.•First theoretical treatment of a previously overlooked force for acceleration of a laser-dressed atom.•Means to obtain new evidence for the Kramers-Henneberg atom, a theoretical concept needing experimental confirmation.•A striking case of stable motions produced by combining rapidly oscillating and static electric fields.Superstrong femtosecond pulsed lasers can profoundly alter electronic structure of atoms and molecules. The oscillating laser field drives one or more electrons almost free. When averaged over, the rapid oscillations combine with the static Coulomb potential to create an effective binding potential. The consequent array of bound states comprises the “Kramers-Henneberger Atom”. Theorists have brought forth many properties of KH atoms, yet convincing experimental evidence is meager. We examine a remarkable experiment accelerating atoms (Eichmann et al., 2009). It offers tantalizing evidence for the KH atom, with prospects for firm confirmation by adjustment of laser parameters.Download high-res image (49KB)Download full-size image
Co-reporter:Yiteng Zhang, Sangchul Oh, Fahhad H. Alharbi, Gregory S. Engel and Sabre Kais
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 8) pp:5743-5750
Publication Date(Web):16 Jan 2015
DOI:10.1039/C4CP05310A
The high quantum efficiency of photosynthetic complexes has inspired researchers to explore new routes to utilize this process for photovoltaic devices. Quantum coherence has been demonstrated to play a crucial role in this process. Herein, we propose a three-dipole system as a model of a new photocell type which exploits the coherence among its three dipoles. We have proved that the efficiency of such a photocell is greatly enhanced by quantum coherence. We have also predicted that the photocurrents can be enhanced by about 49.5% in such a coherent coupled dipole system compared with the uncoupled dipoles. These results suggest a promising novel design aspect of photosynthesis-mimicking photovoltaic devices.
Co-reporter:Ross. D. Hoehn;Ashley. M. Schreder
Interdisciplinary Sciences: Computational Life Sciences 2014 Volume 6( Issue 4) pp:312-322
Publication Date(Web):2014 December
DOI:10.1007/s12539-012-0236-4
Cellular agent-based models are a technique that can be easily adapted to describe nuances of a particular cell type. Within we have concentrated on the cellular particularities of the human Endothelial Cell, explicitly the effects both of anchorage dependency and of heightened scaffold binding on the total confluence time of a system. By expansion of a discrete, homogeneous, asynchronous cellular model to account for several states per cell (phases within a cell’s life); we accommodate and track dependencies of confluence time and population dynamics on these factors. Increasing the total motility time, analogous to weakening the binding between lattice and cell, affects the system in unique ways from increasing the average cellular velocity; each degree of freedom allows for control over the time length the system achieves logistic growth and confluence. These additional factors may allow for greater control over behaviors of the system. Examinations of system’s dependence on both seed state velocity and binding are also enclosed.
Co-reporter:Jing Zhu and Sabre Kais, Patrick Rebentrost and Alán Aspuru-Guzik
The Journal of Physical Chemistry B 2011 Volume 115(Issue 6) pp:1531-1537
Publication Date(Web):January 26, 2011
DOI:10.1021/jp109559p
We present a detailed theoretical study of the transfer of electronic excitation energy through the Fenna−Matthews−Olson (FMO) pigment−protein complex, using the newly developed modified scaled hierarchical approach (Shi, Q.; et al. J. Chem. Phys.2009, 130, 084105). We show that this approach is computationally more efficient than the original hierarchical approach. The modified approach reduces the truncation levels of the auxiliary density operators and the correlation function. We provide a systematic study of how the number of auxiliary density operators and the higher-order correlation functions affect the exciton dynamics. The time scales of the coherent beating are consistent with experimental observations. Furthermore, our theoretical results exhibit population beating at physiological temperature. Additionally, the method does not require a low-temperature correction to obtain the correct thermal equilibrium at long times.
Co-reporter:Hefeng Wang, Sabre Kais, Alán Aspuru-Guzik and Mark R. Hoffmann
Physical Chemistry Chemical Physics 2008 vol. 10(Issue 35) pp:5388-5393
Publication Date(Web):22 Jul 2008
DOI:10.1039/B804804E
Simulating a quantum system is more efficient on a quantum computer than on a classical computer. The time required for solving the Schrödinger equation to obtain molecular energies has been demonstrated to scale polynomially with system size on a quantum computer, in contrast to the well-known result of exponential scaling on a classical computer. In this paper, we present a quantum algorithm to obtain the energy spectrum of molecular systems based on the multiconfigurational self-consistent field (MCSCF) wave function. By using a MCSCF wave function as the initial guess, the excited states are accessible. Entire potential energy surfaces of molecules can be studied more efficiently than if the simpler Hartree–Fock guess was employed. We show that a small increase of the MCSCF space can dramatically increase the success probability of the quantum algorithm, even in regions of the potential energy surface that are far from the equilibrium geometry. For the treatment of larger systems, a multi-reference configuration interaction approach is suggested. We demonstrate that such an algorithm can be used to obtain the energy spectrum of the water molecule.
Co-reporter:Alejandro Ferrón, Pablo Serra, Sabre Kais
Chemical Physics Letters 2008 Volume 461(1–3) pp:127-130
Publication Date(Web):8 August 2008
DOI:10.1016/j.cplett.2008.06.061
Abstract
We present dimensional scaling calculations for the critical parameters needed to bind one and two-electrons to a finite linear dipole field and the stability diagram for the hydrogen–antihydrogen like molecules. We find that calculations at the large-D limit are much simpler that D = 3, yet yield similar results for the critical parameters and the stability diagrams.
Co-reporter:Winton Moy, Marcelo A. Carignano and Sabre Kais
The Journal of Physical Chemistry A 2008 Volume 112(Issue 24) pp:5448-5452
Publication Date(Web):May 21, 2008
DOI:10.1021/jp800346z
We combined the finite-size scaling method with the finite element method to provide a systematic procedure for obtaining quantum critical parameters for a quantum system. We present results for the Yukawa potential solved with the finite element approach. The finite-size scaling approach was then used to find the critical parameters of the system. The critical values λc, α, and ν were found to be 0.83990345, 2.0002, and 1.002, respectively, for l = 0. These results compare well with the theoretically exact values for α and ν and with the best numerical estimations for λc. The finite element method is general and can be extended to larger systems.
Co-reporter:Hefeng Wang
Israel Journal of Chemistry 2007 Volume 47(Issue 1) pp:59-65
Publication Date(Web):10 MAR 2010
DOI:10.1560/IJC.47.1.59
We study the relation between quantum entanglement and electron correlation in quantum chemistry calculations. We prove that the Hartree–Fock (HF) wave function does not violate Bell's inequality, and thus is not entangled, whereas the configuration interaction (CI) wave function is entangled since it violates Bell's inequality. Entanglement is related to electron correlation and might be used as an alternative measure of the electron correlation in quantum chemistry calculations. As an example we show the calculations of entanglement for the H2 molecule and how it correlates with the traditional electron correlation, which is the difference between the exact and the HF energies.
Co-reporter:Pablo Serra, Sabre Kais
Chemical Physics Letters 2003 Volume 372(1–2) pp:205-209
Publication Date(Web):22 April 2003
DOI:10.1016/S0009-2614(03)00371-3
Abstract
We present a finite-size scaling approach for the calculations of the critical parameters for binding an electron to an electric dipole field. This approach gives very accurate results for the critical parameters by using a systematic expansion in a finite basis set. The approach is general and could be used to obtain the critical conditions for stable dipole-bound dianions.
Co-reporter:Hefeng Wang, Sabre Kais, Alán Aspuru-Guzik and Mark R. Hoffmann
Physical Chemistry Chemical Physics 2008 - vol. 10(Issue 35) pp:NaN5393-5393
Publication Date(Web):2008/07/22
DOI:10.1039/B804804E
Simulating a quantum system is more efficient on a quantum computer than on a classical computer. The time required for solving the Schrödinger equation to obtain molecular energies has been demonstrated to scale polynomially with system size on a quantum computer, in contrast to the well-known result of exponential scaling on a classical computer. In this paper, we present a quantum algorithm to obtain the energy spectrum of molecular systems based on the multiconfigurational self-consistent field (MCSCF) wave function. By using a MCSCF wave function as the initial guess, the excited states are accessible. Entire potential energy surfaces of molecules can be studied more efficiently than if the simpler Hartree–Fock guess was employed. We show that a small increase of the MCSCF space can dramatically increase the success probability of the quantum algorithm, even in regions of the potential energy surface that are far from the equilibrium geometry. For the treatment of larger systems, a multi-reference configuration interaction approach is suggested. We demonstrate that such an algorithm can be used to obtain the energy spectrum of the water molecule.
Co-reporter:Yiteng Zhang, Sangchul Oh, Fahhad H. Alharbi, Gregory S. Engel and Sabre Kais
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 8) pp:NaN5750-5750
Publication Date(Web):2015/01/16
DOI:10.1039/C4CP05310A
The high quantum efficiency of photosynthetic complexes has inspired researchers to explore new routes to utilize this process for photovoltaic devices. Quantum coherence has been demonstrated to play a crucial role in this process. Herein, we propose a three-dipole system as a model of a new photocell type which exploits the coherence among its three dipoles. We have proved that the efficiency of such a photocell is greatly enhanced by quantum coherence. We have also predicted that the photocurrents can be enhanced by about 49.5% in such a coherent coupled dipole system compared with the uncoupled dipoles. These results suggest a promising novel design aspect of photosynthesis-mimicking photovoltaic devices.
Co-reporter:Yiteng Zhang, Aaron Wirthwein, Fahhad H. Alharbi, Gregory S. Engel and Sabre Kais
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 46) pp:NaN31849-31849
Publication Date(Web):2016/11/07
DOI:10.1039/C6CP06098F
The high efficiency of the photon-to-charge conversion process found in photosynthetic complexes has inspired researchers to explore a new route for designing artificial photovoltaic materials. Quantum coherence can provide a mean to surpass the Shockley–Quiesser device concept limit by reducing the radiative recombination. Taking inspiration from these new discoveries, we consider a linearly-aligned system as a light-harvesting antennae composed of two-level optical emitters coupled with each other by dipole–dipole interactions. Our simulations show that the certain dark states can enhance the power with the aid of intra-band phononic dissipation. Due to cooperative effects, the output power will be improved when incorporating more emitters in the linear system.
