336 research outputs found
Linear optical quantum computation with imperfect entangled photon-pair sources and inefficient non-photon-number-resolving detectors
We propose a scheme for efficient cluster state quantum computation by using
imperfect polarization-entangled photon-pair sources, linear optical elements
and inefficient non-photon-number-resolving detectors. The efficiency threshold
for loss tolerance in our scheme requires the product of source and detector
efficiencies should be >1/2 - the best known figure. This figure applies to
uncorrelated loss. We further find that the loss threshold is unaffected by
correlated loss in the photon pair source. Our approach sheds new light on
efficient linear optical quantum computation with imperfect experimental
conditions.Comment: 5 pages, 2 figure
Analogue to multiple electromagnetically induced transparency in all-optical drop-filter systems
We theoretically study a parallel optical configuration which includes N
periodically coupled whispering-gallery-mode resonators. The model shows an
obvious effect which has a direct analogy with the phenomenon of multiple
electromagnetically induced transparency in quantum systems. The numerical
simulations illuminate that the frequency transparency windows are sharp and
highly transparent. We also briefly discuss the experimental feasibility of the
current scheme in two practical systems, microrings and microdisks.Comment: 4 pages, 4 figure
High visibility on-chip quantum interference of single surface plasmons
Quantum photonic integrated circuits (QPICs) based on dielectric waveguides
have been widely used in linear optical quantum computation. Recently, surface
plasmons have been introduced to this application because they can confine and
manipulate light beyond the diffraction limit. In this study, the on-chip
quantum interference of two single surface plasmons was achieved using
dielectric-loaded surface-plasmon-polariton waveguides. The high visibility
(greater than 90%) proves the bosonic nature of single plasmons and emphasizes
the feasibility of achieving basic quantum logic gates for linear optical
quantum computation. The effect of intrinsic losses in plasmonic waveguides
with regard to quantum information processing is also discussed. Although the
influence of this effect was negligible in the current experiment, our studies
reveal that such losses can dramatically reduce quantum interference visibility
in certain cases; thus, quantum coherence must be carefully considered when
designing QPIC devices.Comment: 6 pages, 4 figure
Break the efficiency limitations of dissipative Kerr soliton using nonlinear couplers
Dissipative Kerr soliton (DKS) offers a compact solution of coherent comb
sources and holds huge potential for applications, but has long been suffering
from poor power conversion efficiency when driving by a continuous-wave laser.
Here, a general approach to resolving this challenge is provided. By deriving
the critical coupling condition of a multimode nonlinear optics system in a
generalized theoretical framework, two efficiency limitations of the
conventional pump method of DKS are revealed: the effective coupling rate is
too small and is also power-dependent. Nonlinear couplers are proposed to
sustain the DKS indirectly through nonlinear energy conversion processes,
realizing a power-adaptive effective coupling rate to the DKS and matching the
total dissipation rate of the system, which promises near-unity power
conversion efficiencies. For instance, a conversion efficiency exceeding
is predicted for aluminum nitride microrings with a nonlinear coupler
utilizing second-harmonic generation. The nonlinear coupler approach for
high-efficiency generation of DKS is experimentally feasible as its mechanism
applies to various nonlinear processes, including Raman and Brillouin
scattering, and thus paves the way of micro-solitons towards practical
applications.Comment: 8 pages, 3 figure
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