127 research outputs found
Low Temperature Studies of Charge Dynamics of Nitrogen-Vacancy Defect in Diamond
In this paper, we study the photoinduced switching of the nitrogen-vacancy
(NV) center between two different charge states - negative (NV-) and neutral
(NV0) at liquid helium temperature. The conversion of NV- to NV0 on a single
defect is experimentally proven and its rate scales quadratically with power
under resonant excitation. In addition, we found that resonant excitation of
the neutral NV changes the charge state, recovering its negative configuration.
This type of conversion significantly improves spectral stability of NV- defect
and allows high fidelity initialization of the spin qubit. A possible mechanism
for ionization and recovery of the NV- defect is discussed. This study provides
better understanding of the charge dynamics of the NV center, which is relevant
for quantum information processing based on NV defect in diamond.Comment: 5 pages, 4 figure
Integrated Diamond Optics for Single Photon Detection
Optical detection of single defect centers in the solid state is a key
element of novel quantum technologies. This includes the generation of single
photons and quantum information processing. Unfortunately the brightness of
such atomic emitters is limited. Therefore we experimentally demonstrate a
novel and simple approach that uses off-the-shelf optical elements. The key
component is a solid immersion lens made of diamond, the host material for
single color centers. We improve the excitation and detection of single
emitters by one order of magnitude, as predicted by theory.Comment: 10 pages, 3 figure
Photo induced ionization dynamics of the nitrogen vacancy defect in diamond investigated by single shot charge state detection
The nitrogen-vacancy centre (NV) has drawn much attention for over a decade,
yet detailed knowledge of the photophysics needs to be established. Under
typical conditions, the NV can have two stable charge states, negative (NV-) or
neutral (NV0), with photo induced interconversion of these two states. Here, we
present detailed studies of the ionization dynamics of single NV centres in
bulk diamond at room temperature during illumination in dependence of the
excitation wavelength and power. We apply a recent method which allows us to
directly measure the charge state of a single NV centre, and observe its
temporal evolution. Results of this work are the steady state NV- population,
which was found to be always < 75% for 450 to 610 nm excitation wavelength, the
relative absorption cross-section of NV- for 540 to 610 nm, and the energy of
the NV- ground state of 2.6 eV below the conduction band. These results will
help to further understand the photo-physics of the NV centre.Comment: 9 pages, 7 figure
Coherence of single spins coupled to a nuclear spin bath of varying density
The dynamics of single electron and nuclear spins in a diamond lattice with
different 13C nuclear spin concentration is investigated. It is shown that
coherent control of up to three individual nuclei in a dense nuclear spin
cluster is feasible. The free induction decays of nuclear spin Bell states and
single nuclear coherences among 13C nuclear spins are compared and analyzed.
Reduction of a free induction decay time T2* and a coherence time T2 upon
increase of nuclear spin concentration has been found. For diamond material
with depleted concentration of nuclear spin, T2* as long as 30 microseconds and
T2 of up to 1.8 ms for the electron spin has been observed. The 13C
concentration dependence of T2* is explained by Fermi contact and dipolar
interactions with nuclei in the lattice. It has been found that T2 decreases
approximately as 1/n, where n is 13C concentration, as expected for an electron
spin interacting with a nuclear spin bath.Comment: 4 pages, 4 figures, 1 movie (avi), 1 supplementary material (pdf
Engineering chromium related single photon emitters in single crystal diamond
Color centers in diamond as single photon emitters, are leading candidates
for future quantum devices due to their room temperature operation and
photostability. The recently discovered chromium related centers are
particularly attractive since they possess narrow bandwidth emission and a very
short lifetime. In this paper we investigate the fabrication methodologies to
engineer these centers in monolithic diamond. We show that the emitters can be
successfully fabricated by ion implantation of chromium in conjunction with
oxygen or sulfur. Furthermore, our results indicate that the background
nitrogen concentration is an important parameter, which governs the probability
of success to generate these centers.Comment: 14 pages, 5 figure
- …