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dephasing eflfects in topological insulators

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Frontiers of physics 2019年第4期14卷 47-61页

作者： Junjie Qi Haiwen Liu Hua Jiang X.C.Xie International Center for Quantum Materials and School of Physics Peking University Beijing 100871 China Collaborative Innovation Center of Quantum Matter Beijing China Center for Advanced Quantum Studies Department of Physics Beijing Normal University Beijing 100875China School of Physical Science and Technology Soochow University Suzhou 215006 China Institute for Advanced Study Soochow University Suzhou 215006 China

Topological insulators,a class of typical topological materials in both two dimensions and three dimensions,are insulating in bulk and metallic at *** spin-momentum locked surface states and peculiar transport properties exhibit promising potential applications on quantum devices,which generate extensive interest in the last *** is the process of the loss of phase coherence,which inevitably exists in a realistic *** this review,we focus on recent progress in dephasing effects on the topological *** general,there are two types of dephasing processes:normal dephasing and spin *** two-dimensional topological insulators,the phenomenologically numerical investigation shows that the longitudinal resistance plateaus is robust against normal dephasing but fragile with spin *** microscopic mechanisms of spin dephasing are then *** three-dimensional topological insulators,the helical surface states exhibit a helical spin texture due to the spin-momentum locking ***,normal dephasing has close connection to spin dephasing in this case,and gives rise to anomalous "gap-like" *** effects on properties of helical surface states are investigated.

关键词： dephasing effects topological insulators backscattering

A virtual sequencer reveals the dephasing patterns in error-correction code DNA sequencing

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National Science Review 2021年第5期8卷 91-100页

作者： Wenxiong Zhou Li Kang Haifeng Duan Shuo Qiao Louis Tao Zitian Chen Yanyi Huang Biomedical Pioneering Innovation Center (BIOPIC) School of Life SciencesBeijing Advanced Innovation Center for Genomics(ICG)and Peking-Tsinghua Center for Life SciencesPeking University Center for Bioinformatics State Key Laboratory of Protein Engineering and Plant Genetic EngineeringPeking University Center for Quantitative Biology Peking University College of Engineering Peking University College of Chemistry and Molecular Engineering Peking University Institute for Cell Analysis Chinese Institute for Brain Research (CIBR)

An error-correction code(ECC) sequencing approach has recently been reported to effectively reduce sequencing errors by interrogating a DNA fragment with three orthogonal degenerate sequencing-by-synthesis(SBS) reactions. However, similar to other non-single-molecule SBS methods, the reaction will gradually lose its synchronization within a molecular colony in ECC sequencing. This phenomenon, called dephasing, causes sequencing error, and in ECC sequencing, induces distinctive dephasing patterns. To understand the characteristic dephasing patterns of the dual-base flowgram in ECC sequencing and to generate a correction algorithm, we built a virtual sequencer in silico. Starting from first principles and based on sequencing chemical reactions, we simulated ECC sequencing results, identified the key factors of dephasing in ECC sequencing chemistry and designed an effective dephasing *** results show that our dephasing algorithm is applicable to sequencing signals with at least 500 cycles, or1000-bp average read length, with acceptably low error rate for further parity checks and ECC *** virtual sequencer with our dephasing algorithm can further be extended to a dichromatic form of ECC sequencing, allowing for a potentially much more accurate sequencing approach.

关键词： DNA sequencing error-correction code dephasing computer simulation sequencing-by-synthesis

Role of phase fluctuation and dephasing in the enhancing continuous variable entanglement of a two-photon coherent beat laser

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Chinese Physics B 2012年第1期21卷 210-221页

作者： Sintayehu Tesfa Max Planck Institute for the Physics of Complex Systems Nthnitzer Str.3801187 DresdenGermany Physics DepartmentDilla UniversityP.O.Box 419DillaEthiopia

A steady state analysis of the nonclassical features and statistical properties of the cavity radiation of a two- photon coherent beat laser is presented. Results show that the degree of two-mode squeezing, detectable entanglement and intensity of the cavity radiation can increase with the deviation of the phase fluctuations of the laser employed in preparing the atoms, but decrease with the increasing rate at which the induced coherence superposition decays. Although it is found that varying the phase fluctuations and dephasing can lead to modification in the quantum features and statistical properties of the radiation, it does not alter the similarity in the nature of the degree of entanglement detectable by the criteria following from Duan-Giedke-Cirac Zoller and logarithmic negativity in a perceivable manner. Since the intensity and quantum features can be readily enhanced, this system is expected to be a viable source of a strong robust entangled （squeezed） light under various conditions. Moreover, comparison of the mean number of photon pairs with intensity difference shows that the chance of inciting a two-photon process can be enhanced by changing the rate of dephasing and phase fluctuations.

关键词： coherent beat laser phase fluctuations dephasing entanglement

Ultrafast dephasing of interband transitions in semiconductors

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Science China Mathematics 2001年第10期44卷 1340-1348页

作者：张海潮邓莉文锦辉廖睿赖天树林位株 State Key Laboratory of Ultrafast Laser Spectroscopy Department of Physics Zhongshan University Guangzhou China

Two basic types of dephasing mechanisms, carrier-carrier and carrier-phonon scattering including hole-hole and hole-phonon scattering are proposed in the theory of ultrafast polarization dephasing of continuum transitions in bulk semiconductors. The contribution of optical phonon scattering to the dephasing rate is the average of the scattering rates for electrons and holes. A weighting factor that reflects the change in the momentum of the particle in a collision is introduced into the usual integral of the carrier-carrier scattering rate to describe the contribution of carrier-carrier scattering to the dephasing rate for the case of static screening interaction. The theoretical calculations are in quantitative agreement with the reported experimental results.

关键词： femtosecond spectroscopy optical polarization dephasing

Prefect Protection of Quantum-Enhanced Metrology from dephasing Noise

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Communications in Theoretical Physics 2017年第4期67卷 383-390页

作者：钟伟黄奕筱王晓光 Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials SPTESouth China Normal University School of Science Zhejiang University of Science and Technology Zhejiang Institute of Modern Physics Department of PhysicsZhejiang University

One of the main obstacles for quantum-enhanced metrology is that the estimation accuracy enhanced by non-classical states is likely to be obliterated by noises. Here, we consider a scenario of phase estimation suffering from pure dephasing noise which is taken into account after the phase parameter being imprinted, and propose a scheme to effectively protect the quantum enhancement from both correlated and uncorrelated dephasing sources by performing a rotation operation prior to the noise. By invoking the Fisher information approach, we strictly prove that a π/2 rotation is the ideal one which can completely resist the influence of the phase noise for all real symmetric pure states and the optimal measurement approaching the ultimate sensitivity set by quantum Cramér–Rao bound is ***, we numerically study the availability of the scheme with arbitrary angle rotation for different probe states and show that our scheme will still robust for general symmetric pure states even with non-ideal rotation operation.

关键词： quantum-enhanced metrology dephasing optimal measurement

Optical Bloch Equations Modified with Phonon-Induced Intensity-Dependent dephasing

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Communications in Theoretical Physics 2007年第2X期48卷 335-338页

作者： ZHOU Guang-Hua LI Yao-Yi CHENG Mu-Tian LIU Shao-Ding WANG Qu-Quan Department of Physics Wuhan University Wuhan 430072 China State Key Laboratory for Surface Physics Institute of Physicsthe Chinese Academy of Sciences Beijing 100080 China

We extend the exciton population equations of a two-level quantum dot system with weak excitation to the ones with strong excitations, in which, the phonon-induced intensity-dependent dephasing time and decay rate are involved. The straightforward calculated populations from the modified population equations demonstrate the damping behavior of Rabi oscillation as the external field increasing. The effect of the intensity-dependent dephasing time and the intensity-dependent decay rate are also discussed.

关键词： decoherence dephasing optical Bloch equation quantum dot

Traveling-wave parametric amplifiere-induced qubit dephasing:analysis and mitigation

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Chip 2023年第4期2卷 97-104页

作者： Yingshan Zhang Huikai Xu Yu Song Yuqun Xu Shuang Yang Ziyue Hua Shoukuan Zhao Weiyang Liu Guangming Xue Yirong Jin Haifeng Yu Beijing Academy of Quantum Information Sciences Beijing 100193China Center for Quantum Information Institute for Interdisciplinary Information SciencesTsinghua UniversityBeijing 100084China Hefei National Laboratory Hefei 230088China

The mitigation of dephasing poses a significant challenge toimproving the performance of error-prone superconducting quantum computing ***,the dephasing of a transmon qubit ina dispersive readout regime was investigated by adopting aJosephson traveling-wave parametric amplifier as the *** findings reveal that the potent pump leakage from the preamplifier may lead to severe *** could be attributed to amixture of measurement-induced dephasing,ac Stark effect,*** is showed that pulse-mode readout is a promising measurement scheme to mitigate qubit dephasing while minimizing theneed for bulky *** work provides key insights intomitigating decoherence from microwave-pumped preamplifiers,which will be critical for advancing large-scale quantum computers.

关键词： TWPA Microwave pump dephasing Pulse mode

Rotational dephasing of the molecular alignment by centrifugal distortion [Invited]

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Chinese Optics Letters 2022年第10期20卷 20-24页

作者： Yunxia Huang Guizhen Liu Shuwu Xu School of Science Nantong UniversityNantong 226019China

The dephasing of molecular alignment can lead to the deformation of the alignment signal during its periodic *** studies are concentrated on the first few rotational revival periods of the molecular alignment and neglect the dephasing ***,study of the alignment dephasing is still of great significance for both the long-term dynamics of the molecular alignment and the dephasing *** this work,we theoretically demonstrate that the dephasing effect is correlated with both the rotational temperature and the rotational revival period of the *** results present that the dephasing is especially significant for those molecules with long rotational revival period at high rotational *** physics behind it is explored by taking advantage of the coherence of the rotational quantum state *** work deepens our understanding of rotational dynamics and rotational spectroscopy in molecular alignment.

关键词： dephasing molecular alignment centrifugal distortion rotational state population

Simulation of the influence of imperfections on dynamical decoupling of a superconducting qubit

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Chinese Physics B 2019年第6期28卷 38-44页

作者： Ying-Shan Zhang Jian-She Liu Chang-Hao Zhao Yong-Cheng He Da Xu Wei Chen Department of Microelectronics and Nanoelectronics Tsinghua UniversityBeijing 100084China Institute of Microelectronics Tsinghua UniversityBeijing 100084China Tsinghua National Laboratory for Information Science and Technology Tsinghua UniversityBeijing 100084China

Dynamical decoupling is widely used in many quantum computing systems to combat decoherence. In a practical superconducting quantum system, imperfections can plague decoupling performance. In this work, imperfections in a superconducting qubit and its control system are modeled via modified Hamiltonian and collapse operator. A master equation simulation is carried out on the qubit under 1/f environment noise spectrum. The average dephasing rate of qubit is extracted to characterize the impact of different imperfections on the decoupling from dephasing. We find that the precision of pulse position, on–off ratio, and filtering effect are most critical. Bounded pulses have weaker impact,while variation in pulse width and qubit relaxation are insignificant. Consequently, alternative decoupling protocols, jitter mitigation, cascaded mixers, and pulse shaping can be conducive to the performance of decoupling. This work may assist the analysis and optimization of dynamical decoupling on noisy superconducting quantum systems.

关键词： dynamical decoupling superconducting qubit imperfection dephasing