Evolution equation for quantum coherence

Hu, Ming‐Liang; Fan, Heng

doi:10.1038/srep29260

Cited by 91 publications

(74 citation statements)

References 63 publications

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“…and for E F above E A and E M , (5) indicates that the beating pattern forms only when the Fermi energy E F is between E M and E A . Here, the beating pattern arises because of the topological nature of the semimetal, different from the Zeeman splitting [39,40,65], nested Fermi surfaces [34], and orbital quantum interference [66].…”

Section: Refmentioning

confidence: 99%

Anomalous Phase Shift of Quantum Oscillations in 3D Topological Semimetals

2016

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Berry phase physics is closely related to a number of topological states of matter. Recently discovered topological semimetals are believed to host a nontrivial π Berry phase to induce a phase shift of ±1/8 in the quantum oscillation (+ for hole and − for electron carriers). We theoretically study the Shubnikov-de Haas oscillation of Weyl and Dirac semimetals, taking into account their topological nature and inter-Landau band scattering. For a Weyl semimetal with broken timereversal symmetry, the phase shift is found to change nonmonotonically and go beyond known values of ±1/8 and ±5/8. For a Dirac semimetal or paramagnetic Weyl semimetal, time-reversal symmetry leads to a discrete phase shift of ±1/8 or ±5/8, as a function of the Fermi energy. Different from the previous works, we find that the topological band inversion can lead to beating patterns in the absence of Zeeman splitting. We also find the resistivity peaks should be assigned integers in the Landau index plot. Our findings may account for recent experiments in Cd2As3 and should be helpful for exploring the Berry phase in various 3D systems. The Shubnikov-de Haas oscillation of resistance in a metal arises from the Landau quantization of electronic states under strong magnetic fields. The oscillation can be described by the Lifshitz-Kosevich formula [1] cos[2π(F/B + φ)], where B is the magnitude of magnetic field, and the oscillation frequency F and phase shift φ can provide valuable information about the Fermi surface topography of materials. It is widely believed that an energy band with linear dispersion carries an extra π Berry phase [2, 3], leading to phase shifts of φ = 0 and ±1/8 in 2D and 3D, respectively, compared with ±1/2 and ±5/8 for parabolic energy bands without the Berry phase (+ for hole and − for electron carriers). Topological semimetals [4][5][6][7][8] provide a new platform to study the nontrivial Berry phase in 3D. They have linear dispersion near the Weyl nodes at which the conduction and valence bands touch. The Weyl nodes host monopoles connected by Fermi arcs, and have been discovered in the Dirac semimetals Na 3 Bi [9-11] and Cd 3 As 2 [12][13][14][15][16][17][18][19], and the Weyl semimetals TaAs family [20][21][22][23][24][25][26][27][28][29] and YbMnBi 2 [30].Exploring the π Berry phase in 3D semimetals remains difficult [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46]. To extract the phase shift, the Landau indices, i.e., where F/B + φ takes integers n, need to be identified first from the magnetoresistivity. A plot of n vs 1/B then extrapolates to the phase shift on the n axis. However, the first step in 3D is highly nontrivial. In 3D, a magnetic field quantizes the energy spectrum into a set of 1D bands of Landau levels. There may be multiple Landau bands on the Fermi surface and scattering among them. This situation never occurs for discrete Landau levels in 2D. It is not intuitive to determine the Landau indices in 3D without a sophisticated theoretical analysis of the resistivity of the Landau ban...

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Section: Refmentioning

confidence: 99%

Anomalous Phase Shift of Quantum Oscillations in 3D Topological Semimetals

2016

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“…On the other hand, compared with quantum correlation, quantum coherence is another basic notion in quantum theory and has witnessed an on‐going interest in pursuing the relevant quantification in recent years . It derives from the quantum state superposition principle, and is regarded as a physical resource in optics experiments and various quantum technologies, such as quantum thermodynamics, quantum sensing and metrology, and quantum biological systems .…”

Section: Introductionmentioning

confidence: 99%

Multipartite Quantum Coherence and Distribution under the Unruh Effect

Ding

Shi

et al. 2018

Annalen der Physik

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Quantum coherence of the tripartite W state and Greenberger-Horne-Zeilinger (GHZ) state under the Unruh effect are explored based on the model of a two-level detector qubit coupled to a massless scalar field. The results reveal that Unruh thermal noise really destroys tripartite quantum resources. It is worth mentioning that the quantum coherence of the GHZ state reaches zero in the infinite acceleration limit, but that of the W-state always remains nonzero. Coherence of the GHZ state displays a sudden death as the coupling parameter grows, while coherence freezing can be witnessed for the W state. It can be concluded that the W state is more robust than the GHZ state against Unruh radiation. Moreover, the related investigation can be expanded to N-qubit quantum systems and the corresponding analytical solution is obtained. It indicates that the larger number W-type entangled qubit can be as a better quantum resource for quantum information tasks under the Unruh effect.

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“…The answer to the second question is in the affirmative. There are, indeed, two recent articles by Hu and Fan [1,2] dealing with 3-dimensional Gell-Mann channels. They are defined with the use of the Kraus operators, and then it is assumed that their eigenvectors are the Gell-Mann matrices.…”

Section: Two Channelsmentioning

confidence: 99%

“…For the Gell-Mann channel given by its eigenvalue equations, we found its time-local generator together with the conditions under which this generator has the corresponding GKSL form. The EV Gell-Mann channels can be used in the theory of quantum coherences and quantum correlation measures [1,2]. It was shown that, under certain circumstances, the evolution equations of coherences and correlation measures obey the factorization relation.…”

Section: Applications and Final Thoughtsmentioning

confidence: 99%