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Artículos de revistas sobre el tema "Electronic quantum coherence"

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Publicado: 4 de mayo de 2024

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1

Fassioli, Francesca, Rayomond Dinshaw, Paul C. Arpin y Gregory D. Scholes. "Photosynthetic light harvesting: excitons and coherence". Journal of The Royal Society Interface 11, n.º 92 (6 de marzo de 2014): 20130901. http://dx.doi.org/10.1098/rsif.2013.0901.

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Photosynthesis begins with light harvesting, where specialized pigment–protein complexes transform sunlight into electronic excitations delivered to reaction centres to initiate charge separation. There is evidence that quantum coherence between electronic excited states plays a role in energy transfer. In this review, we discuss how quantum coherence manifests in photosynthetic light harvesting and its implications. We begin by examining the concept of an exciton, an excited electronic state delocalized over several spatially separated molecules, which is the most widely available signature of quantum coherence in light harvesting. We then discuss recent results concerning the possibility that quantum coherence between electronically excited states of donors and acceptors may give rise to a quantum coherent evolution of excitations, modifying the traditional incoherent picture of energy transfer. Key to this (partially) coherent energy transfer appears to be the structure of the environment, in particular the participation of non-equilibrium vibrational modes. We discuss the open questions and controversies regarding quantum coherent energy transfer and how these can be addressed using new experimental techniques.

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2

Palato, Samuel, Hélène Seiler, Parmeet Nijjar, Oleg Prezhdo y Patanjali Kambhampati. "Atomic fluctuations in electronic materials revealed by dephasing". Proceedings of the National Academy of Sciences 117, n.º 22 (14 de mayo de 2020): 11940–46. http://dx.doi.org/10.1073/pnas.1916792117.

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The microscopic origin and timescale of the fluctuations of the energies of electronic states has a significant impact on the properties of interest of electronic materials, with implication in fields ranging from photovoltaic devices to quantum information processing. Spectroscopic investigations of coherent dynamics provide a direct measurement of electronic fluctuations. Modern multidimensional spectroscopy techniques allow the mapping of coherent processes along multiple time or frequency axes and thus allow unprecedented discrimination between different sources of electronic dephasing. Exploiting modern abilities in coherence mapping in both amplitude and phase, we unravel dissipative processes of electronic coherences in the model system of CdSe quantum dots (QDs). The method allows the assignment of the nature of the observed coherence as vibrational or electronic. The expected coherence maps are obtained for the coherent longitudinal optical (LO) phonon, which serves as an internal standard and confirms the sensitivity of the technique. Fast dephasing is observed between the first two exciton states, despite their shared electron state and common environment. This result is contrary to predictions of the standard effective mass model for these materials, in which the exciton levels are strongly correlated through a common size dependence. In contrast, the experiment is in agreement with ab initio molecular dynamics of a single QD. Electronic dephasing in these materials is thus dominated by the realistic electronic structure arising from fluctuations at the atomic level rather than static size distribution. The analysis of electronic dephasing thereby uniquely enables the study of electronic fluctuations in complex materials.

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3

Zhu, Ruidan, Meixia Ruan, Hao Li, Xuan Leng, Jiading Zou, Jiayu Wang, Hailong Chen, Zhuan Wang y Yuxiang Weng. "Vibrational and vibronic coherences in the energy transfer process of light-harvesting complex II revealed by two-dimensional electronic spectroscopy". Journal of Chemical Physics 156, n.º 12 (28 de marzo de 2022): 125101. http://dx.doi.org/10.1063/5.0082280.

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The presence of quantum coherence in light-harvesting complex II (LHCII) as a mechanism to understand the efficiency of the light-harvesting function in natural photosynthetic systems is still debated due to its structural complexity and weak-amplitude coherent oscillations. Here, we revisit the coherent dynamics and clarify different types of coherences in the energy transfer processes of LHCII using a joint method of the high-S/N transient grating and two-dimensional electronic spectroscopy. We find that the electronic coherence decays completely within 50 fs at room temperature. The vibrational coherences of chlorophyll a dominate over oscillations within 1 ps, whereas a low-frequency mode of 340 cm−1 with a vibronic mixing character may participate in vibrationally assisted energy transfer between chlorophylls a. Our results may suggest that vibronic mixing is relevant for rapid energy transfer processes among chlorophylls in LHCII.

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4

Wu, Yanling, Qiong Wu, Fei Sun, Cai Cheng, Sheng Meng y Jimin Zhao. "Emergence of electron coherence and two-color all-optical switching in MoS2 based on spatial self-phase modulation". Proceedings of the National Academy of Sciences 112, n.º 38 (8 de septiembre de 2015): 11800–11805. http://dx.doi.org/10.1073/pnas.1504920112.

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Generating electron coherence in quantum materials is essential in optimal control of many-body interactions and correlations. In a multidomain system this signifies nonlocal coherence and emergence of collective phenomena, particularly in layered 2D quantum materials possessing novel electronic structures and high carrier mobilities. Here we report nonlocal ac electron coherence induced in dispersed MoS2 flake domains, using coherent spatial self-phase modulation (SSPM). The gap-dependent nonlinear dielectric susceptibility χ(3) measured is surprisingly large, where direct interband transition and two-photon SSPM are responsible for excitations above and below the bandgap, respectively. A wind-chime model is proposed to account for the emergence of the ac electron coherence. Furthermore, all-optical switching is achieved based on SSPM, especially with two-color intraband coherence, demonstrating that electron coherence generation is a ubiquitous property of layered quantum materials.

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5

Schwickert, David, Marco Ruberti, Přemysl Kolorenč, Andreas Przystawik, Slawomir Skruszewicz, Malte Sumfleth, Markus Braune et al. "Charge-induced chemical dynamics in glycine probed with time-resolved Auger electron spectroscopy". Structural Dynamics 9, n.º 6 (noviembre de 2022): 064301. http://dx.doi.org/10.1063/4.0000165.

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In the present contribution, we use x-rays to monitor charge-induced chemical dynamics in the photoionized amino acid glycine with femtosecond time resolution. The outgoing photoelectron leaves behind the cation in a coherent superposition of quantum mechanical eigenstates. Delayed x-ray pulses track the induced coherence through resonant x-ray absorption that induces Auger decay. Temporal modulation of the Auger electron signal correlated with specific ions is observed, which is governed by the initial electronic coherence and subsequent vibronic coupling to nuclear degrees of freedom. In the time-resolved x-ray absorption measurement, we monitor the time-frequency spectra of the resulting many-body quantum wave packets for a period of 175 fs along different reaction coordinates. Our experiment proves that by measuring specific fragments associated with the glycine dication as a function of the pump-probe delay, one can selectively probe electronic coherences at early times associated with a few distinguishable components of the broad electronic wave packet created initially by the pump pulse in the cation. The corresponding coherent superpositions formed by subsets of electronic eigenstates and evolving along parallel dynamical pathways show different phases and time periods in the range of [Formula: see text] and [Formula: see text] fs. Furthermore, for long delays, the data allow us to pinpoint the driving vibrational modes of chemical dynamics mediating charge-induced bond cleavage along different reaction coordinates.

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6

Lombardi, Federico, Alessandro Lodi, Ji Ma, Junzhi Liu, Michael Slota, Akimitsu Narita, William K. Myers, Klaus Müllen, Xinliang Feng y Lapo Bogani. "Quantum units from the topological engineering of molecular graphenoids". Science 366, n.º 6469 (28 de noviembre de 2019): 1107–10. http://dx.doi.org/10.1126/science.aay7203.

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Robustly coherent spin centers that can be integrated into devices are a key ingredient of quantum technologies. Vacancies in semiconductors are excellent candidates, and theory predicts that defects in conjugated carbon materials should also display long coherence times. However, the quantum performance of carbon nanostructures has remained stunted by an inability to alter the sp2-carbon lattice with atomic precision. Here, we demonstrate that topological tailoring leads to superior quantum performance in molecular graphene nanostructures. We unravel the decoherence mechanisms, quantify nuclear and environmental effects, and observe spin-coherence times that outclass most nanomaterials. These results validate long-standing assumptions on the coherent behavior of topological defects in graphene and open up the possibility of introducing controlled quantum-coherent centers in the upcoming generation of carbon-based optoelectronic, electronic, and bioactive systems.

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7

Novelli, Fabio, Jonathan O. Tollerud, Dharmalingam Prabhakaran y Jeffrey A. Davis. "Persistent coherence of quantum superpositions in an optimally doped cuprate revealed by 2D spectroscopy". Science Advances 6, n.º 9 (febrero de 2020): eaaw9932. http://dx.doi.org/10.1126/sciadv.aaw9932.

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Quantum materials displaying intriguing magnetic and electronic properties could be key to the development of future technologies. However, it is poorly understood how the macroscopic behavior emerges in complex materials with strong electronic correlations. While measurements of the dynamics of excited electronic populations have been able to give some insight, they have largely neglected the intricate dynamics of quantum coherence. Here, we apply multidimensional coherent spectroscopy to a prototypical cuprate and report unprecedented coherent dynamics persisting for ~500 fs, originating directly from the quantum superposition of optically excited states separated by 20 to 60 meV. These results reveal that the states in this energy range are correlated with the optically excited states at ~1.5 eV and point to nontrivial interactions between quantum many-body states on the different energy scales. In revealing these dynamics and correlations, we demonstrate that multidimensional coherent spectroscopy can interrogate complex quantum materials in unprecedented ways.

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8

Kim, Jeongho, Shaul Mukamel y Gregory D. Scholes. "Two-Dimensional Electronic Double-Quantum Coherence Spectroscopy". Accounts of Chemical Research 42, n.º 9 (15 de septiembre de 2009): 1375–84. http://dx.doi.org/10.1021/ar9000795.

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9

Hamilton, James R., Edoardo Amarotti, Carlo N. Dibenedetto, Marinella Striccoli, Raphael D. Levine, Elisabetta Collini y Francoise Remacle. "Time–Frequency Signatures of Electronic Coherence of Colloidal CdSe Quantum Dot Dimer Assemblies Probed at Room Temperature by Two-Dimensional Electronic Spectroscopy". Nanomaterials 13, n.º 14 (18 de julio de 2023): 2096. http://dx.doi.org/10.3390/nano13142096.

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Electronic coherence signatures can be directly identified in the time–frequency maps measured in two-dimensional electronic spectroscopy (2DES). Here, we demonstrate the theory and discuss the advantages of this approach via the detailed application to the fast-femtosecond beatings of a wide variety of electronic coherences in ensemble dimers of quantum dots (QDs), assembled from QDs of 3 nm in diameter, with 8% size dispersion in diameter. The observed and computed results can be consistently characterized directly in the time–frequency domain by probing the polarization in the 2DES setup. The experimental and computed time–frequency maps are found in very good agreement, and several electronic coherences are characterized at room temperature in solution, before the extensive dephasing due to the size dispersion begins. As compared to the frequency–frequency maps that are commonly used in 2DES, the time–frequency maps allow exploiting electronic coherences without additional post-processing and with fewer 2DES measurements. Towards quantum technology applications, we also report on the modeling of the time–frequency photocurrent response of these electronic coherences, which paves the way to integrating QD devices with classical architectures, thereby enhancing the quantum advantage of such technologies for parallel information processing at room temperature.

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10

Kobayashi, Yuki y Stephen R. Leone. "Characterizing coherences in chemical dynamics with attosecond time-resolved x-ray absorption spectroscopy". Journal of Chemical Physics 157, n.º 18 (14 de noviembre de 2022): 180901. http://dx.doi.org/10.1063/5.0119942.

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Coherence can drive wave-like motion of electrons and nuclei in photoexcited systems, which can yield fast and efficient ways to exert materials’ functionalities beyond the thermodynamic limit. The search for coherent phenomena has been a central topic in chemical physics although their direct characterization is often elusive. Here, we highlight recent advances in time-resolved x-ray absorption spectroscopy (tr-XAS) to investigate coherent phenomena, especially those that utilize the eminent light source of isolated attosecond pulses. The unparalleled time and state sensitivities of tr-XAS in tandem with the unique element specificity render the method suitable to study valence electronic dynamics in a wide variety of materials. The latest studies have demonstrated the capabilities of tr-XAS to characterize coupled electronic–structural coherence in small molecules and coherent light–matter interactions of core-excited excitons in solids. We address current opportunities and challenges in the exploration of coherent phenomena, with potential applications for energy- and bio-related systems, potential crossings, strongly driven solids, and quantum materials. With the ongoing developments in both theory and light sources, tr-XAS holds great promise for revealing the role of coherences in chemical dynamics.

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11

DiVincenzo, David P. y Daniel Loss. "Quantum computers and quantum coherence". Journal of Magnetism and Magnetic Materials 200, n.º 1-3 (octubre de 1999): 202–18. http://dx.doi.org/10.1016/s0304-8853(99)00315-7.

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12

Yu, Chang-shui, Yang Zhang y Haiqing Zhao. "Quantum correlation via quantum coherence". Quantum Information Processing 13, n.º 6 (11 de febrero de 2014): 1437–56. http://dx.doi.org/10.1007/s11128-014-0739-5.

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13

Ezawa, Z. F. "Quantum coherence in quantum Hall ferromagnet". Physica B: Condensed Matter 249-251 (junio de 1998): 841–44. http://dx.doi.org/10.1016/s0921-4526(98)00327-5.

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14

Duan, Hong-Guang, Valentyn I. Prokhorenko, Richard J. Cogdell, Khuram Ashraf, Amy L. Stevens, Michael Thorwart y R. J. Dwayne Miller. "Nature does not rely on long-lived electronic quantum coherence for photosynthetic energy transfer". Proceedings of the National Academy of Sciences 114, n.º 32 (25 de julio de 2017): 8493–98. http://dx.doi.org/10.1073/pnas.1702261114.

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During the first steps of photosynthesis, the energy of impinging solar photons is transformed into electronic excitation energy of the light-harvesting biomolecular complexes. The subsequent energy transfer to the reaction center is commonly rationalized in terms of excitons moving on a grid of biomolecular chromophores on typical timescales <100 fs. Today’s understanding of the energy transfer includes the fact that the excitons are delocalized over a few neighboring sites, but the role of quantum coherence is considered as irrelevant for the transfer dynamics because it typically decays within a few tens of femtoseconds. This orthodox picture of incoherent energy transfer between clusters of a few pigments sharing delocalized excitons has been challenged by ultrafast optical spectroscopy experiments with the Fenna–Matthews–Olson protein, in which interference oscillatory signals up to 1.5 ps were reported and interpreted as direct evidence of exceptionally long-lived electronic quantum coherence. Here, we show that the optical 2D photon echo spectra of this complex at ambient temperature in aqueous solution do not provide evidence of any long-lived electronic quantum coherence, but confirm the orthodox view of rapidly decaying electronic quantum coherence on a timescale of 60 fs. Our results can be considered as generic and give no hint that electronic quantum coherence plays any biofunctional role in real photoactive biomolecular complexes. Because in this structurally well-defined protein the distances between bacteriochlorophylls are comparable to those of other light-harvesting complexes, we anticipate that this finding is general and directly applies to even larger photoactive biomolecular complexes.

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15

Haug, Hartmut. "Quantum Coherence in Ultrafast Semiconductor Spectroscopy". Journal of Nonlinear Optical Physics & Materials 07, n.º 02 (junio de 1998): 227–39. http://dx.doi.org/10.1142/s0218863598000193.

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Coherent optical phenomena such as the optical Stark effect, Rabi flopping, photon echo and quantum beating which are well-known in atomic spectroscopy can also be observed in semiconductors by using femtosecond laser pulses. On these short time scales, the quantum coherence of the optical excitations in the solid do not only influence the optical properties but change at the same time the relaxation and dephasing kinetics. The quasi-classical Boltzmann kinetics has to be replaced by quantum kinetics. Coherence leads to the appearance of memory in the scattering integrals. For femtosecond four-wave mixing and pump-and-probe spectroscopy the use of quantum kinetics for LO-phonon and for carrier-carrier scattering will be reviewed.

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16

Dawlaty, Jahan M., Akihito Ishizaki, Arijit K. De y Graham R. Fleming. "Microscopic quantum coherence in a photosynthetic-light-harvesting antenna". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 370, n.º 1972 (13 de agosto de 2012): 3672–91. http://dx.doi.org/10.1098/rsta.2011.0207.

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We briefly review the coherent quantum beats observed in recent two-dimensional electronic spectroscopy experiments in a photosynthetic-light-harvesting antenna. We emphasize that the decay of the quantum beats in these experiments is limited by ensemble averaging. The in vivo dynamics of energy transport depends upon the local fluctuations of a single photosynthetic complex during the energy transfer time (a few picoseconds). Recent analyses suggest that it remains possible that the quantum-coherent motion may be robust under individual realizations of the environment-induced fluctuations contrary to intuition obtained from condensed phase spectroscopic measurements and reduced density matrices. This result indicates that the decay of the observed quantum coherence can be understood as ensemble dephasing. We propose a fluorescence-detected single-molecule experiment with phase-locked excitation pulses to investigate the coherent dynamics at the level of a single molecule without hindrance by ensemble averaging. We discuss the advantages and limitations of this method. We report our initial results on bulk fluorescence-detected coherent spectroscopy of the Fenna–Mathews–Olson complex.

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17

Cheng, Yuan-Chung y Graham R. Fleming. "Coherence Quantum Beats in Two-Dimensional Electronic Spectroscopy". Journal of Physical Chemistry A 112, n.º 18 (mayo de 2008): 4254–60. http://dx.doi.org/10.1021/jp7107889.

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18

Mančal, Tomáš, Leonas Valkunas, Elizabeth L. Read, Gregory S. Engel, Tessa R. Calhoun y Graham R. Fleming. "Electronic coherence transfer in photosynthetic complexes and its signatures in optical spectroscopy". Spectroscopy 22, n.º 2-3 (2008): 199–211. http://dx.doi.org/10.1155/2008/714573.

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Effects of electronic coherence transfer after photoexcitation of excitonic complexes and their manifestation in optical spectroscopy are discussed. A general excitonic model Hamiltonian is considered in detail to elucidate the origin of energy relaxation in excitonic complexes. We suggest that the second-order quantum master equation for the reduced density matrix of electronic degrees of freedom provides the most suitable theoretical framework for the study of coherence transfer in photosynthetic bacteriochlorophyll complexes. Temperature dependence of the absorption band maximum of a simple excitonic dimer is interpreted in terms of coherence transfer between two excited states. The role of reorganization energy of the transitions in the magnitude of the effect is discussed. A large reorganization energy difference between the two states is found to induce significant band shift. The predictions of the theory are compared to experimental measurements of the bacterial reaction center absorption spectra ofRhodobacter sphaeroidesAs an example of a time-dependent spectroscopic method sensitive to coherences and possibly to their transfer, we present recent two-dimensional photon echo measurements of energy relaxation in the so-called Fenna–Matthews–Olson complex ofChlorobium tepidum, where distinct oscillatory patters predicted to be signatures of electronic coherence have been observed.

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19

Assouline, A., L. Pugliese, H. Chakraborti, Seunghun Lee, L. Bernabeu, M. Jo, K. Watanabe et al. "Emission and coherent control of Levitons in graphene". Science 382, n.º 6676 (15 de diciembre de 2023): 1260–64. http://dx.doi.org/10.1126/science.adf9887.

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Flying qubits encode quantum information in propagating modes instead of stationary discrete states. Although photonic flying qubits are available, the weak interaction between photons limits the efficiency of conditional quantum gates. Conversely, electronic flying qubits can use Coulomb interactions, but the weaker quantum coherence in conventional semiconductors has hindered their realization. In this work, we engineered on-demand injection of a single electronic flying qubit state and its manipulation over the Bloch sphere. The flying qubit is a Leviton propagating in quantum Hall edge channels of a high-mobility graphene monolayer. Although single-shot qubit readout and two-qubit operations are still needed for a viable manipulation of flying qubits, the coherent manipulation of an itinerant electronic state at the single-electron level presents a highly promising alternative to conventional qubits.

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20

Gianani, Ilaria, Alessio Belenchia, Stefano Gherardini, Vincenzo Berardi, Marco Barbieri y Mauro Paternostro. "Diagnostics of quantum-gate coherences deteriorated by unitary errors via end-point-measurement statistics". Quantum Science and Technology 8, n.º 4 (22 de agosto de 2023): 045018. http://dx.doi.org/10.1088/2058-9565/acedca.

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Abstract Quantum coherence is a central ingredient in quantum physics with several theoretical and technological ramifications. We consider a figure of merit encoding the information on how the coherence generated on average by a quantum gate is affected by unitary errors (coherent noise sources) in the form of rotation-angle and rotation-axis errors. We provide numerical evidences that such information is well captured by the statistics of local energy measurements on the output states of the gate. These findings are then corroborated by experimental data taken in a quantum optics setting.

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21

Berrada, K. "Quantum coherence in quantum dot systems". Physica E: Low-dimensional Systems and Nanostructures 116 (febrero de 2020): 113784. http://dx.doi.org/10.1016/j.physe.2019.113784.

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22

Loudon, R. "Coherence and Quantum Optics V". Optica Acta: International Journal of Optics 33, n.º 1 (enero de 1986): 13. http://dx.doi.org/10.1080/716099692.

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23

He, Mengyun, Yu Huang, Huimin Sun, Yu Fu, Peng Zhang, Chenbo Zhao, Kang L. Wang, Guoqiang Yu y Qing Lin He. "Quantum anomalous Hall interferometer". Journal of Applied Physics 133, n.º 8 (28 de febrero de 2023): 084401. http://dx.doi.org/10.1063/5.0140086.

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Electronic interferometries in integer and fractional quantum Hall regimes have unfolded the coherence, correlation, and statistical properties of interfering constituents. This is addressed by investigating the roles played by the Aharonov–Bohm effect and Coulomb interactions on the oscillations of transmission/reflection. Here, we construct magnetic interferometers using Cr-doped (Bi,Sb)2Te3 films and demonstrate the electronic interferometry using chiral edge states in the quantum anomalous Hall regime. By controlling the extent of edge coupling and the amount of threading magnetic flux, distinct interfering patterns were observed, which highlight the interplay between the Coulomb interactions and Aharonov–Bohm interference by edge states. The observed interference is likely to exhibit a long-range coherence and robustness against thermal smearing probably owing to the long-range magnetic order. Our interferometer establishes a platform for (quasi)particle interference and topological qubits.

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24

Sederberg, Shawn y Paul B. Corkum. "Perspective on phase-controlled currents in semiconductors driven by structured light". Applied Physics Letters 120, n.º 16 (18 de abril de 2022): 160504. http://dx.doi.org/10.1063/5.0089345.

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Controlling electrons with ever-greater precision is central to both classical and quantum electronics. Since the invention of the laser, virtually every property of coherent light has been tamed, making it one of the most precise tools available to science, technology, and medicine. Coherent control involves the transduction of an exquisitely defined property of light to an electronic system, imparting coherence to an attribute of its constituent electrons. Early developments in coherent control utilized Gaussian laser beams and spatially averaged measurements. The spatial structure and orbital angular momentum of laser light provide additional degrees of freedom for steering electronic and quasiparticle excitations in condensed matter systems. In this Perspective, we first introduce the concept of coherent control in semiconductors. We then proceed to discuss the application of structured light beams to coherent control and the requirement for spatially resolved current detection. Subsequently, we present an overview of recent experiments that were performed using cylindrical vector beams and laser beams with structured phase fronts. Finally, we provide an outlook on the horizons that have emerged with these developments and future directions of interest.

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25

Calhoun, Tessa R. y Graham R. Fleming. "Quantum coherence in photosynthetic complexes". physica status solidi (b) 248, n.º 4 (10 de enero de 2011): 833–38. http://dx.doi.org/10.1002/pssb.201000856.

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26

Hays, M., V. Fatemi, D. Bouman, J. Cerrillo, S. Diamond, K. Serniak, T. Connolly et al. "Coherent manipulation of an Andreev spin qubit". Science 373, n.º 6553 (22 de julio de 2021): 430–33. http://dx.doi.org/10.1126/science.abf0345.

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Two promising architectures for solid-state quantum information processing are based on electron spins electrostatically confined in semiconductor quantum dots and the collective electrodynamic modes of superconducting circuits. Superconducting electrodynamic qubits involve macroscopic numbers of electrons and offer the advantage of larger coupling, whereas semiconductor spin qubits involve individual electrons trapped in microscopic volumes but are more difficult to link. We combined beneficial aspects of both platforms in the Andreev spin qubit: the spin degree of freedom of an electronic quasiparticle trapped in the supercurrent-carrying Andreev levels of a Josephson semiconductor nanowire. We performed coherent spin manipulation by combining single-shot circuit–quantum-electrodynamics readout and spin-flipping Raman transitions and found a spin-flip time TS = 17 microseconds and a spin coherence time T2E = 52 nanoseconds. These results herald a regime of supercurrent-mediated coherent spin-photon coupling at the single-quantum level.

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27

CHENAUD, B., C. CHAUBET, B. JOUAULT, L. SAMINADAYAR, D. MAILLY, G. FAINI y A. CAVANNA. "ARE AHARONOV–BOHM EFFECT AND QUANTIZED HALL REGIME COMPATIBLE?" International Journal of Nanoscience 02, n.º 06 (diciembre de 2003): 535–41. http://dx.doi.org/10.1142/s0219581x03001656.

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We present calculations of the quantum oscillations appearing in the transmission of a mesoscopic GaAs / GaAlAs ring isolated by quantum point contacts. We show that the device acts as an electronic Fabry–Perot spectrometer in the quantum Hall effect regime, and discuss the effect of the coherence length of edge states.

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28

Wang, Wei y Mitsuo Takeda. "Conservation Laws in Quantum-Correlation-Function Dynamics". Advances in Optical Technologies 2010 (22 de junio de 2010): 1–8. http://dx.doi.org/10.1155/2010/171254.

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For a complete and lucid discussion of quantum correlation, we introduced two new first-order correlation tensors defined as linear combinations of the general coherence tensors of the quantized fields and derived the associated coherence potentials governing the propagation of quantum correlation. On the basis of these quantum optical coherence tensors, we further introduced new concepts of scalar, vector and tensor densities and presented some related properties, such as conservation laws and the wave-particle duality for quantum correlation, which provide new insights into photon statistics and quantum correlation.

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29

Ding Feng, 丁峰, 丁玉强 Ding Yuqiang, 韩森 Han Sen y 胡雪元 Hu Xueyuan. "量子相干在量子热力学中演化规律的研究". Chinese Journal of Lasers 48, n.º 12 (2021): 1212003. http://dx.doi.org/10.3788/cjl202148.1212003.

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30

Bauerle, Christopher, Pascal Degiovanni y Laurent Saminadayar. "Quantum coherence and magnetic scattering". International Journal of Nanotechnology 7, n.º 4/5/6/7/8 (2010): 403. http://dx.doi.org/10.1504/ijnt.2010.031727.

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31

ISHIZAKI, Akihito. "Electronic Energy Transfer and Quantum Coherence in Photosynthetic Light Harvesting". Review of Laser Engineering 41, n.º 6 (2013): 391. http://dx.doi.org/10.2184/lsj.41.6_391.

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32

Rudolph, M. y J. J. Heremans. "Electronic and quantum phase coherence properties of bismuth thin films". Applied Physics Letters 100, n.º 24 (11 de junio de 2012): 241601. http://dx.doi.org/10.1063/1.4729035.

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33

Hwang, Inchan y Gregory D. Scholes. "Electronic Energy Transfer and Quantum-Coherence in π-Conjugated Polymers†". Chemistry of Materials 23, n.º 3 (8 de febrero de 2011): 610–20. http://dx.doi.org/10.1021/cm102360x.

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34

Pile, David. "Quantum tools for classical coherence". Nature Photonics 7, n.º 1 (27 de diciembre de 2012): 80. http://dx.doi.org/10.1038/nphoton.2012.330.

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35

Hradil, Zdeněk, Jaroslav Řeháček, Luis Sánchez-Soto y Berthold-Georg Englert. "Quantum Fisher information with coherence". Optica 6, n.º 11 (14 de noviembre de 2019): 1437. http://dx.doi.org/10.1364/optica.6.001437.

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36

Chávez-Huerta, M. y F. Rojas. "Local quantum uncertainty as a robust metric to characterize discord-like quantum correlations in subsets of the chromophores in photosynthetic light-harvesting complexes". Revista Mexicana de Física 66, n.º 4 Jul-Aug (1 de julio de 2020): 525. http://dx.doi.org/10.31349/revmexfis.66.525.

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Green sulfur bacteria is a photosynthetic organism whose light-harvesting complex accommodates a pigment-protein complex called Fenna-Matthews-Olson (FMO). The FMO complex sustains quantum coherence and quantum correlations between the electronic states of spatially separated pigment molecules as energy moves with nearly a 100% quantum efficiency to the reaction center. We present a method based on the quantum uncertainty associated to local measurements to quantify discord-like quantum correlations between two subsystems where one is a qubit and the other is a qudit. We implement the method by calculating local quantum uncertainty (LQU), concurrence, and coherence between subsystems of pure and mixed states represented by the eigenstates and by the thermal equilibrium state determined by the FMO Hamiltonian. Three partitions of the seven chromophores network define the subsystems: one chromophore with six chromophores, pairs of chromophores, and one chromophore with two chromophores. Implementation of the LQU approach allows us to characterize quantum correlations that had not been studied before, identify the most quantum correlated subsets of chromophores, and determine that, in the strongest associations of chromophores, the LQU is a monotonically increasing function of the coherence.

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37

Guo, Cheng, Jin Lin, Lian-Chen Han, Na Li, Li-Hua Sun, Fu-Tian Liang, Dong-Dong Li et al. "Low-latency readout electronics for dynamic superconducting quantum computing". AIP Advances 12, n.º 4 (1 de abril de 2022): 045024. http://dx.doi.org/10.1063/5.0088879.

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Dynamic quantum computing can support quantum error correction circuits to build a large general-purpose quantum computer, which requires electronic instruments to perform the closed-loop operation of readout, processing, and control within 1% of the qubit coherence time. In this paper, we present low-latency readout electronics for dynamic superconducting quantum computing. The readout electronics use a low-latency analog-to-digital converter to capture analog signals, a field-programmable gate array (FPGA) to process digital signals, and the general I/O resources of the FPGA to forward the readout results. Running an algorithm based on the design of multichannel parallelism and single instruction multiple data on an FPGA, the readout electronics achieve a readout latency of 40 ns from the last sample input to the readout valid output. The feedback data link for cross-instrument communication shows a communication latency of 48 ns when 16 bits of data are transmitted over a 2 m-length cable using a homologous clock to drive the transceiver. With codeword-based triggering mechanisms, readout electronics can be used in dynamic superconducting quantum computing.

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38

AWSCHALOM, DAVID D. "CONTROLLING SPIN COHERENCE WITH SEMICONDUCTOR NANOSTRUCTURES". International Journal of Modern Physics B 22, n.º 01n02 (20 de enero de 2008): 111–12. http://dx.doi.org/10.1142/s0217979208046165.

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We present two emerging opportunities for manipulating and communicating coherent spin states in semiconductors. First, we show that semiconductor microcavities offer unique means of controlling light-matter interactions in confined geometries, resulting in a wide range of applications in optical communications and inspiring proposals for quantum information processing and computational schemes. Studies of spin dynamics in microcavities — a new and promising research field — have revealed novel effects such as polarization beats, stimulated spin scattering, and giant Faraday rotation. Here, we study the electron spin dynamics in optically-pumped GaAs microdisk lasers with quantum wells and interface-fluctuation quantum dots in the active region. In particular, we examine how the electron spin dynamics are modified by the stimulated emission in the disks, and observe an enhancement of the spin coherence time when the optical excitation is in resonance with a high quality ( Q ~ 5000) lasing mode.1 This resonant enhancement, contrary to expectations from the observed trend in the carrier recombination time, is then manipulated by altering the cavity design and dimensions. In analogy to devices based on excitonic coherence, this ability to engineer coherent interactions between electron spins and photons may provide novel pathways towards spin dependent quantum optoelectronics. In a second example, the nitrogen-vacancy (N-V) center in diamond has garnered interest as a room-temperature solid-state system not only for exploring electronic and nuclear spin phenomena but also as a candidate for spin-based quantum information processing. Spin coherence times of up to 50 microseconds have been reported for ensembles of N-V centers and a two-qubit gate utilizing the electron spin of a N-V center and the nuclear spin of a nearby C-13 atom has been demonstrated. Here, we present experiments using angle-resolved magneto-photoluminescence microscopy to investigate anisotropic spin interactions of single N-V centers in diamond at room temperature.2 Negative peaks in the photoluminescence intensity are observed as a function of both magnetic field magnitude and angle, and can be explained by coherent spin precession and anisotropic relaxation at spin-level anticrossings. Additionally, precise field alignment with the symmetry axis of a single N-V center reveals the resonant magnetic dipolar coupling of a single "bright" electron spin of an N-V center to small numbers of "dark" spins of nitrogen defects in its immediate vicinity, which are otherwise undetected by photoluminescence. Most recently, we are exploring the possibility of utilizing this magnetic dipole coupling between bright and dark spins to couple two spatially separated single N-V center spins by means of intermediate nitrogen spins. Note from Publisher: This article contains the abstract only.

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39

Schulman, L. S. y B. Gaveau. "Quantum coherence and Carnot engines". Physica E: Low-dimensional Systems and Nanostructures 29, n.º 1-2 (octubre de 2005): 289–96. http://dx.doi.org/10.1016/j.physe.2005.05.026.

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40

Arpin, Paul C., Mihail Popa y Daniel B. Turner. "Signatures of Duschinsky Rotation in Femtosecond Coherence Spectra". AppliedMath 2, n.º 4 (1 de diciembre de 2022): 675–86. http://dx.doi.org/10.3390/appliedmath2040039.

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The motions of nuclei in a molecule can be mathematically described by using normal modes of vibration, which form a complete orthonormal basis. Each normal mode describes oscillatory motion at a frequency determined by the momentum of the nuclei. Near equilibrium, it is common to apply the quantum harmonic-oscillator model, whose eigenfunctions intimately involve combinatorics. Each electronic state has distinct force constants; therefore, each normal-mode basis is distinct. Duschinsky proposed a linearized approximation to the transformation between the normal-mode bases of two electronic states using a rotation matrix. The rotation angles are typically obtained by using quantum-chemical computations or via gas-phase spectroscopy measurements. Quantifying the rotation angles in the condensed phase remains a challenge. Here, we apply a two-dimensional harmonic model that includes a Duschinsky rotation to condensed-phase femtosecond coherence spectra (FCS), which are created in transient–absorption spectroscopy measurements through impulsive excitation of coherent vibrational wavepackets. Using the 2D model, we simulate spectra to identify the signatures of Duschinsky rotation. The results suggest that peak multiplicities and asymmetries may be used to quantify the rotation angle, which is a key advance in condensed-phase molecular spectroscopy.

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41

Ho, Mae‐Wan. "Quantum coherence and conscious experience". Kybernetes 26, n.º 3 (abril de 1997): 265–76. http://dx.doi.org/10.1108/03684929710163164.

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42

Elliott, D. S. "Optical Coherence and Quantum Optics [Book review]". IEEE Spectrum 33, n.º 9 (septiembre de 1996): 12–13. http://dx.doi.org/10.1109/mspec.1996.535254.

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43

Le Jeune, P., X. Marie, T. Amand, M. Brousseau y J. Barrau. "Coherence of Excitons in Quantum Wells". physica status solidi (a) 164, n.º 1 (noviembre de 1997): 527–33. http://dx.doi.org/10.1002/1521-396x(199711)164:1<527::aid-pssa527>3.0.co;2-l.

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44

Borgarino, Mattia y Alessandro Badiali. "Quantum Gates for Electronics Engineers". Electronics 12, n.º 22 (15 de noviembre de 2023): 4664. http://dx.doi.org/10.3390/electronics12224664.

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The design of a solid-state quantum processor is nowadays a hot research topic in microelectronics. Like the logic gates in a classical processor, quantum gates serve as the fundamental building blocks for quantum processors. The main goal of the present paper is to deduce the matrix of the main one- and two-qubit quantum gates from the Schrödinger equation. The mathematical formalism is kept as comfortable as possible for electronics engineers. This paper does not cover topics such as dissipations, state density, coherence, and state purity. In a similar manner, this paper also deals with the quantum nature of a quantum processor by leveraging the concept of a finite-state machine, which is a background notion for any electronics engineer.

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45

Palinginis, Phedon y Hailin Wang. "Coherent Raman scattering from electron spin coherence in GaAs quantum wells". Journal of Magnetism and Magnetic Materials 272-276 (mayo de 2004): 1919–20. http://dx.doi.org/10.1016/j.jmmm.2003.12.1186.

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46

Duan, Hong-Guang, Valentyn I. Prokhorenko, Richard J. Cogdell, Khuram Ashraf, Amy L. Stevens, Emilie Wientjes, Roberta Croce, Michael Thorwart y R. J. Dwayne Miller. "Lack of long-lived quantum coherence in the photosynthetic energy transfer". EPJ Web of Conferences 205 (2019): 09035. http://dx.doi.org/10.1051/epjconf/201920509035.

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We have studied the FMO, LHCII and PSII reaction center complex by electronic 2D spectroscopy. At ambient temperature the electronic coherences are too short lived to play any functional role in the natural energy transfer.

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47

Du, Luojun, Jian Tang, Jing Liang, Mengzhou Liao, Zhiyan Jia, Qinghua Zhang, Yanchong Zhao et al. "Giant Valley Coherence at Room Temperature in 3R WS2 with Broken Inversion Symmetry". Research 2019 (13 de octubre de 2019): 1–8. http://dx.doi.org/10.34133/2019/6494565.

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Breaking the space-time symmetries in materials can markedly influence their electronic and optical properties. In 3R-stacked transition metal dichalcogenides, the explicitly broken inversion symmetry enables valley-contrasting Berry curvature and quantization of electronic angular momentum, providing an unprecedented platform for valleytronics. Here, we study the valley coherence of 3R WS2 large single-crystal with thicknesses ranging from monolayer to octalayer at room temperature. Our measurements demonstrate that both A and B excitons possess robust and thickness-independent valley coherence. The valley coherence of direct A (B) excitons can reach 0.742 (0.653) with excitation conditions on resonance with it. Such giant and thickness-independent valley coherence of large single-crystal 3R WS2 at room temperature would provide a firm foundation for quantum manipulation of the valley degree of freedom and practical application of valleytronics.

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48

Yu, Chang-shui, Si-ren Yang y Bao-qing Guo. "Total quantum coherence and its applications". Quantum Information Processing 15, n.º 9 (28 de junio de 2016): 3773–84. http://dx.doi.org/10.1007/s11128-016-1376-y.

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49

Arpin, Paul C. y Daniel B. Turner. "Signatures of Vibrational and Electronic Quantum Beats in Femtosecond Coherence Spectra". Journal of Physical Chemistry A 125, n.º 12 (16 de marzo de 2021): 2425–35. http://dx.doi.org/10.1021/acs.jpca.0c10807.

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50

Rott, P. y M. J. Feldman. "Isolation filters for macroscopic quantum coherence experiment". IEEE Transactions on Appiled Superconductivity 13, n.º 2 (junio de 2003): 970–73. http://dx.doi.org/10.1109/tasc.2003.814116.

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