606 research outputs found
High coherent solid-state qubit from a pair of quantum dots
In this letter we propose a scheme to build up high coherent solid-state
quantum bit (qubit) from two coupled quantum dots. Quantum information is
stored in electron-hole pair state with the electron and hole locating in
different dots, and universal quantum gates involving any pair of qubits are
realized by effective coupling interaction via virtually exchanging cavity
photons.Comment: 3 pages, 1 figur
Quantifying quantum discord and entanglement of formation via unified purifications
We propose a scheme to evaluate the amount of quantum discord and
entanglement of formation for mixed states, and reveal their ordering relation
via an intrinsic relationship between the two quantities distributed in
different partners of the associated purification. This approach enables us to
achieve analytical expressions of the two measures for a sort of quantum
states, such as an arbitrary two-qubit density matrix reduced from pure
three-qubit states and a class of rank-2 mixed states of 4\times 2 systems.
Moreover, we apply the scheme to characterize fully the dynamical behavior of
quantum correlations for the specified physical systems under decoherence.Comment: 4 pages, 2 figures, accepted for publication in Phys. Rev.
Optical Manipulation of Single Electron Spin in Doped and Undoped Quantum Dots
The optical manipulation of electron spins is of great benefit to solid-state
quantum information processing. In this letter, we provide a comparative study
on the ultrafast optical manipulation of single electron spin in the doped and
undoped quantum dots. The study indicates that the experimental breakthrough
can be preliminarily made in the undoped quantum dots, because of the
relatively less demand.Comment: 3 pages, 3 figure
Number-resolved master equation approach to quantum transport under the self-consistent Born approximation
We construct a particle-number(n)-resolved master equation (ME) approach
under the self-consistent Born approximation (SCBA) for quantum transport
through mesoscopic systems. The formulation is essentially non-Markovian and
incorporates the interlay of the multi-tunneling processes and many-body
correlations. The proposed n-SCBA-ME goes completely beyond the scope of the
Born-Markov master equation, being applicable to transport under small bias
voltage, in non-Markovian regime and with strong Coulomb correlations. For
steady state, it can recover not only the exact result of noninteracting
transport under arbitrary voltages, but also the challenging nonequilibrium
Kondo effect. Moreover, the n-SCBA-ME approach is efficient for the study of
shot noise.We demonstrate the application by a couple of representative
examples, including particularly the nonequilibrium Kondo system.Comment: arXiv admin note: substantial text overlap with arXiv:1302.638
Family Portraits: The Reconstruction of “Family Time” Through Generations
Marianne Hirsch’s concept of “liquid time” states that photographs are not fixed into static permanence but remain dynamic and unfixed as they acquire new meanings in new circumstances. I had not considered this concept until I began going through family photographs after my grandfather passed away. There I was, sitting on the sofa in my grandparents’ house, enabled by these photographs to perceive an odd thing—dining scenarios in my family photographsall represented the same behaviour of people holding cups of soft drinks, “clinking”glasses with or toasting each other, and smiling when the photographerpressed the camera shutter. No one considered this behaviour peculiar because it had already become a habit of my family’s dining culture even though my grandfather never drank soft drinks because of his diabetes. Four family photographs present dining scenarios from the 1980s to 2020. These four portraits include three print photographs and one digital photograph, and were taken at different times, by different photographers, at different locations. Within a span of forty years, these four photographs showcase a changing family performance
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