9,877 research outputs found
One-step preparation of cluster states in quantum dot molecules
Cluster states, a special type of highly entangled states, are a universal
resource for measurement-based quantum computation. Here, we propose an
efficient one-step generation scheme for cluster states in semiconductor
quantum dot molecules, where qubits are encoded on singlet and triplet state of
two coupled quantum dots. By applying a collective electrical field or
simultaneously adjusting interdot bias voltages of all double-dot molecule, we
get a switchable Ising-like interaction between any two adjacent quantum
molecule qubits. The initialization, the single qubit measurement, and the
experimental parameters are discussed, which shows the large cluster state
preparation and one-way quantum computation implementable in semiconductor
quantum dots with the present techniques.Comment: 5 pages, 3 figure
Superfluidity and effective mass of magnetoexcitons in topological insulator bilayers: Effect of inter-Landau-level Coulomb interaction
The effective mass and superfluidity-normal phase transition temperature of
magnetoexcitons in topological insulator bilayers are theoretically
investigated. The intra-Landau-level Coulomb interaction is treated
perturbatively, from which the effective magnetoexciton mass is analytically
discussed. The inclusion of inter-Landau-level Coulomb interaction by more
exact numerical diagonalization of the Hamiltonian brings out important
modifications to magnetoexciton properties, which are specially characterized
by prominent reduction in the magnetoexciton effective mass and promotion in
the superfluidity-normal phase transition temperature at a wide range of
external parameters.Comment: 5.6 EPL pages, 4 figure
Probing crossover from analogous weak antilocalization to localization by an Aharonov-Bohm interferometer on topological insulator surface
We propose a scanning tunneling microscopy Aharonov-Bohm (AB) interferometer
on the surface of a topological insulator (TI) to probe the crossover from
analogous weak antilocalization (WAL) to weak localization (WL) phenomenon via
the AB oscillations in spin-resolved local density of states (LDOS). Based on
our analytical and numerical results, we show that with increasing the energy
gap of TI surface states, the = periodic AB oscillations in
spin-resolved LDOS gradually transit into the periodic oscillations.Comment: 4.2 APL pages, 2 figure
Fractional quantum Hall effect of topological surface states under a strong tilted magnetic field
The fractional quantum Hall effect (FQHE) of topological surface-state
particles under a tilted strong magnetic field is theoretically studied by
using the exact diagonalization method. The Haldane's pseudopotentials for the
Coulomb interaction are analytically obtained. The results show that by
increasing the in-plane component of the tilted magnetic field, the FQHE state
at =0 Landau level (LL) becomes more stable, while the stabilities of
= LLs become weaker. Moreover, we find that the excitation gaps of the
FQHE states increase as the tilt angle is increased.Comment: 4.2 pages, 4 figure
(De-)activating the growth machine for redevelopment: the case of Liede urban village in Guangzhou
This research investigates the mechanism of urban village redevelopment in south China. Through a revised typology of place entrepreneurs based on the growth machine thesis and a case study of Liede village in central Guangzhou, it illustrates how land-based interests embedded in an imbalanced power relationship can (de-)activate urban village redevelopment. The study reveals that while urban villagers, as represented by the village collective, have entrenched interests in the redevelopment process, the city government – as monopolistic land manager and place entrepreneur – plays the deciding role in forging and halting a growth machine geared towards urban village redevelopment. Although developers are also part of the process, the (de-)activation of redevelopment growth machine/coalition in Guangzhou has largely been dominated by the city government. With a comparative view on the original growth machine model, it is hoped that this study would furnish both theoretical and practical thoughts for future research
Dispersive Coupling Between the Superconducting Transmission Line Resonator and the Double Quantum Dots
Realization of controllable interaction between distant qubits is one of the
major problems in scalable solid state quantum computing. We study a
superconducting transmission line resonator (TLR) as a tunable dispersive
coupler for the double-dot molecules. A general interaction Hamiltonian of
two-electron spin-based qubits and the TLR is presented, where the double-dot
qubits are biased at the large detuning region and the TLR is always empty and
virtually excited. Our analysis o the main decoherence sources indicates that
various major quantum operations can be reliably implemented with current
technology.Comment: 10 pages, 5 figure
Aharonov-Bohm oscillations in the local density of topological surface states
We study Aharonov-Bohm (AB) oscillations in the local density of states
(LDOS) for topological insulator (TI) and conventional metal Au(111) surfaces
with spin-orbit interaction, which can be probed by spin-polarized scanning
tunneling microscopy. We show that the spacial AB oscillatory period in the
total LDOS is a flux quantum (weak localization) in
both systems. Remarkably, an analogous weak antilocalization with
periodic spacial AB oscillations in spin components of LDOS for TI surface is
observed, while it is absent in Au(111).Comment: 4 APL pages, 3 figure
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