271 research outputs found
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
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
Decoherence and the retrieval of lost information
We found that in contrast with the common premise, a measurement on the
environment of an open quantum system can {\em reduce} its decoherence rate. We
demonstrate it by studying an example of indirect qubit's measurement, where
the information on its state is hidden in the environment. This information is
extracted by a distant device, coupled with the environment. We also show that
the reduction of decoherence generated by this device, is accompanied with
diminution of the environmental noise in a vicinity of the qubit. An
interpretation of these results in terms of quantum interference on large
scales is presented.Comment: 9 pages, 8 figures, additional explanations added, Phys. Rev. B, in
pres
High channel count and high precision channel spacing multi-wavelength laser array for future PICs
Multi-wavelength semiconductor laser arrays (MLAs) have wide applications in wavelength
multiplexing division (WDM) networks. In spite of their tremendous potential, adoption of
the MLA has been hampered by a number of issues, particularly wavelength precision and
fabrication cost. In this paper, we report high channel count MLAs in which the wavelengths
of each channel can be determined precisely through low-cost standard μm-level
photolithography/holographic lithography and the reconstruction-equivalent-chirp (REC)
technique. 60-wavelength MLAs with good wavelength spacing uniformity have been
demonstrated experimentally, in which nearly 83% lasers are within a wavelength deviation
of ±0.20 nm, corresponding to a tolerance of ±0.032 nm in the period pitch. As a result of
employing the equivalent phase shift technique, the single longitudinal mode (SLM) yield is
nearly 100%, while the theoretical yield of standard DFB lasers is only around 33.3%
Generation of twisted magnons via spin-to-orbital angular momentum conversion
Twisted magnons (TMs) carrying orbital angular momentum (OAM) have attracted
much attention from the magnonic community. The fabrication of such novel
magnon state however is still challenging. Here we present a simple method to
generate TMs with arbitrary radial and azimuthal quantum numbers through the
spin-to-orbital angular momentum conversion. The conversion rate from
plane-wave magnons to twisted ones is shown to be insensitive to the quantum
index. The spectrum of TMs in thin nanodisks is solved analytically, showing a
good agreement with micromagnetic simulations. Moreover, we numerically study
the propagation of TMs in magnetic nanodisk arrays and obtain the quantitative
dependence of the decay length on quantum indexes. Our results are helpful for
realizing TMs with large OAMs that are indispensable for future high-capacity
magnonic communications and computings.Comment: 6 pages, 4 figure
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