234 research outputs found
Controlling single diamond NV color center photoluminescence spectrum with a Fabry-Perot microcavity
We present both theoretical and experimental results on fluorescence of
single defect centers in diamond nanocrystals embedded in a planar dielectric
microcavity. From a theoretical point of view, we show that the overall
fluorescence collection efficiency using moderate numerical aperture microscope
objective can be enhanced by using a low quality factor microcavity. This could
be used in particular for low temperature applications where the numerical
aperture of collection microscope objectives is limited due to the experimental
constraints. We experimentally investigate the control of the fluorescence
spectrum of the emitted light from a single center. We show the simultaneous
narrowing of the room temperature broadband emission spectrum and the increase
of the fluorescence spectral density.Comment: 22 pages, 10 figure
Frequency tuning of the whispering gallery modes of silica microspheres for CQED and spectroscopy
We have tuned the whispering gallery modes of a fused silica microresonator
over nearly 1 nm at 800 nm, i.e. over 0.5 FSR or 10^6 linewidths of the
resonator. This has been achieved by a new method based on the stretching of a
two-stem microsphere. The devices described below will permit new Cavity-QED
experiments with this high-Q optical resonator when it is desirable to optimize
its coupling to emitters with given transition frequencies. The tuning
capability demonstrated here is compatible with both UHV and low temperature
operation, which should be useful for future experiments with laser cooled
atoms or single quantum dots.Comment: ReVTeX, 4 pages, 3 figure
Narrow-band single-photon emission in the near infrared for quantum key distribution
We report on the observation of single colour centers in natural diamond
samples emitting in the near infrared region when optically excited.
Photoluminescence of these single emitters have several striking features, such
as a narrow-band fully polarized emission (FWHM 2 nm) around 780 nm, a short
excited-state lifetime of about 2 ns, and perfect photostability at room
temperature under our excitation conditions. We present a detailed study of
their photophysical properties. Development of a triggered single-photon source
relying on this single colour centre is discussed in the prospect of its
application to quantum key distribution.Comment: 9 page
Direct Measurement of the Photon Statistics of a Triggered Single Photon Source
We studied intensity fluctuations of a single photon source relying on the
pulsed excitation of the fluorescence of a single molecule at room temperature.
We directly measured the Mandel parameter Q(T) over 4 orders of magnitude of
observation timescale T, by recording every photocount. On timescale of a few
excitation periods, subpoissonian statistics is clearly observed and the
probablility of two-photons events is 10 times smaller than Poissonian pulses.
On longer times, blinking in the fluorescence, due to the molecular triplet
state, produces an excess of noise.Comment: 4 pages, 3 figures, 1 table submitted to Physical Review Letter
Wheeler's delayed-choice thought experiment: Experimental realization and theoretical analysis
Wheeler has strikingly illustrated the wave-particle duality by the
delayed-choice thought experiment, in which the configuration of a 2-path
interferometer is chosen after a single-photon light-pulsed has entered it. We
present a quantitative theoretical analysis of an experimental realization of
Wheeler's proposal
Experimental realization of Wheeler's delayed-choice GedankenExperiment
The quantum "mystery which cannot go away" (in Feynman's words) of
wave-particle duality is illustrated in a striking way by Wheeler's
delayed-choice GedankenExperiment. In this experiment, the configuration of a
two-path interferometer is chosen after a single-photon pulse has entered it :
either the interferometer is \textit{closed} (\textit{i.e.} the two paths are
recombined) and the interference is observed, or the interferometer remains
\textit{open} and the path followed by the photon is measured. We report an
almost ideal realization of that GedankenExperiment, where the light pulses are
true single photons, allowing unambiguous which-way measurements, and the
interferometer, which has two spatially separated paths, produces high
visibility interference. The choice between measuring either the 'open' or
'closed' configuration is made by a quantum random number generator, and is
space-like separated -- in the relativistic sense -- from the entering of the
photon into the interferometer. Measurements in the closed configuration show
interference with a visibility of 94%, while measurements in the open
configuration allow us to determine the followed path with an error probability
lower than 1%
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