3,062 research outputs found
Conquer the fine structure splitting of excitons in self-assembled InAs/GaAs quantum dots via combined stresses
Eliminating the fine structure splitting (FSS) of excitons in self-assembled
quantum dots (QDs) is essential to the generation of high quality entangled
photon pairs. It has been shown that the FSS has a lower bound under uniaxial
stress. In this letter, we show that the FSS of excitons in a general
self-assembled InGaAs/GaAs QD can be fully suppressed via combined stresses
along the [110] and [010] directions. The result is confirmed by atomic
empirical pseudopotential calculations. For all the QDs we studied, the FSS can
be tuned to be vanishingly small ( 0.1 eV), which is sufficient small
for high quality entangled photon emission.Comment: 4 pages, 3 figure, 1 tabl
Cross-correlations mediated by Majorana bound states
We consider the correlated parallel transport through two quantum dots which
are tunnel-coupled to the ends of a semiconductor nanowire where the Majorana
bound states (MBSs) may emerge under proper conditions. In terms of the
cross-correlation of currents, we reveal unusual behaviors originated from the
nonlocal MBSs, including such as the distinct symmetry and antisymmetry of the
spectral density in response to the dot-level modulations, and the vanished
cross correlation occurred when any of the dot-levels is in resonance with the
Majorana zero mode
Demonstrating nonlocality induced teleportation through Majorana bound states in a semiconductor nanowire
It was predicted by Tewari [Phys. Rev. Lett. {\bf 100}, 027001 (2008)] that a
teleportationlike electron transfer phenomenon is one of the novel consequences
of the existence of Majorana fermion, because of the inherently nonlocal
nature. In this work we consider a concrete realization and measurement scheme
for this interesting behavior, based on a setup consisting of a pair of quantum
dots which are tunnel-coupled to a semiconductor nanowire and are jointly
measured by two point-contact detectors. We analyze the teleportation dynamics
in the presence of measurement backaction and discuss how the teleportation
events can be identified from the current trajectories of strong response
detectors.Comment: 5 pages, 3 figure
Robust interface between flying and topological qubits
Hybrid architectures, consisting of conventional and topological qubits, have
recently attracted much attention due to their capability in consolidating the
robustness of topological qubits and the universality of conventional qubits.
However, these two kinds of qubits are normally constructed in significantly
different energy scales, and thus this energy mismatch is a major obstacle for
their coupling that supports the exchange of quantum information between them.
Here, we propose a microwave photonic quantum bus for a direct strong coupling
between the topological and conventional qubits, in which the energy mismatch
is compensated by the external driving field via the fractional ac Josephson
effect. In the framework of tight-binding simulation and perturbation theory,
we show that the energy splitting of the topological qubits in a finite length
nanowire is still robust against local perturbations, which is ensured not only
by topology, but also by the particle-hole symmetry. Therefore, the present
scheme realizes a robust interface between the flying and topological qubits.
Finally, we demonstrate that this quantum bus can also be used to generate
multipartitie entangled states with the topological qubits.Comment: Accepted for publication in Scientific Report
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