318 research outputs found
Coupling single emitters to quantum plasmonic circuits
In recent years the controlled coupling of single photon emitters to
propagating surface plasmons has been intensely studied, which is fueled by the
prospect of a giant photonic non-linearity on a nano-scaled platform. In this
article we will review the recent progress on coupling single emitters to
nano-wires towards the construction of a new platform for strong light-matter
interaction. The control over such a platform might open new doors for quantum
information processing and quantum sensing at the nanoscale, and for the study
of fundamental physics in the ultra-strong coupling regime
On the Quantitative Hardness of CVP
For odd
integers (and ), we show that the Closest Vector Problem
in the norm (\CVP_p) over rank lattices cannot be solved in
2^{(1-\eps) n} time for any constant \eps > 0 unless the Strong Exponential
Time Hypothesis (SETH) fails. We then extend this result to "almost all" values
of , not including the even integers. This comes tantalizingly close
to settling the quantitative time complexity of the important special case of
\CVP_2 (i.e., \CVP in the Euclidean norm), for which a -time
algorithm is known. In particular, our result applies for any
that approaches as .
We also show a similar SETH-hardness result for \SVP_\infty; hardness of
approximating \CVP_p to within some constant factor under the so-called
Gap-ETH assumption; and other quantitative hardness results for \CVP_p and
\CVPP_p for any under different assumptions
Coupling of a Single Quantum Emitter to End-to-end Aligned Silver Nanowires
We report on the observation of coupling a single nitrogen vacancy (NV)
center in a nanodiamond crystal to a propagating plasmonic mode of silver
nanowires. The nanocrystal is placed either near to the apex of a single silver
nanowire or in the gap between two end-to-end aligned silver nanowires. We
observe an enhancement of the NV-centers' decay rate in both cases as a result
of the coupling to the plasmons. The devices are nano-assembled with a scanning
probe technique. Through simulations, we show that end-to-end aligned silver
nanowires can be used as a controllable splitter for emission from a dipole
emitter.Comment: 5 pages, 4 figure
Observation of spatial quantum correlations induced by multiple scattering of non-classical light
We present the experimental realization of spatial quantum correlations of
photons that are induced by multiple scattering of squeezed light. The quantum
correlation relates photons propagating along two different light trajectories
through the random medium and is infinite in range. Both positive and negative
spatial quantum correlations are observed when varying the quantum state
incident to the multiple scattering medium, and the magnitude of the
correlations is controlled by the number of photons. The experimental results
are in excellent agreement with recent theoretical proposals by implementing
the full quantum model of multiple scattering
Clock transition by continuous dynamical decoupling of a three-level system
We present a novel continuous dynamical decoupling scheme for the
construction of a robust qubit in a three-level system. By means of a clock
transition adjustment, we first show how robustness to environmental noise is
achieved, while eliminating drive-noise, to first-order. We demonstrate this
scheme with the spin sub-levels of the NV-centre's electronic ground state. By
applying drive fields with moderate Rabi frequencies, the drive noise is
eliminated and an improvement of 2 orders of magnitude in the coherence time is
obtained compared to the pure dephasing time. We then show how the clock
transition adjustment can be tuned to eliminate also the second-order effect of
the environmental noise with moderate drive fields. A further improvement of
more than 1 order of magnitude in the coherence time is expected and confirmed
by simulations. Hence, our scheme prolongs the coherence time towards the
lifetime-limit using a relatively simple experimental setup.Comment: 7 pages, 5 figure
Electronic noise-free measurements of squeezed light
We study the implementation of a correlation measurement technique for the
characterization of squeezed light. We show that the sign of the covariance
coefficient revealed from the time resolved correlation data allow us to
distinguish between squeezed, coherent and thermal states. In contrast to the
traditional method of characterizing squeezed light, involving measurement of
the variation of the difference photocurrent, the correlation measurement
method allows to eliminate the contribution of the electronic noise, which
becomes a crucial issue in experiments with dim sources of squeezed light.Comment: submitted for publicatio
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