252 research outputs found
The value of competitive employment:In-depth accounts of people with intellectual disabilities
Background Increasing the societal participation of people with intellectual disabilities via competitive employment requires a full understanding of what this means to them. This paper aims to provide an in‐depth examination of the lived experiences of people with intellectual disabilities in competitive employment. Method Interviews were conducted with six participants with mild intellectual disability or borderline functioning and good verbal communication skills. Interviews were analysed according to the guidelines of interpretative phenomenological analysis (IPA). Member checks were conducted. Results Analysis yielded three main themes: (a) Building on my life experiences, (b) My place at work and (c) Being a valuable member of society, like everyone else. Conclusions Competitive employment could make a substantial contribution to the sense of belonging to society and quality of life of people with intellectual disabilities. Nevertheless, they must cope with stigma‐related obstacles and feelings of being dependent on others in the work environment
Entanglement of dark electron-nuclear spin defects in diamond
A promising approach for multi-qubit quantum registers is to use optically
addressable spins to control multiple dark electron-spin defects in the
environment. While recent experiments have observed signatures of coherent
interactions with such dark spins, it is an open challenge to realize the
individual control required for quantum information processing. Here we
demonstrate the initialisation, control and entanglement of individual dark
spins associated to multiple P1 centers, which are part of a spin bath
surrounding a nitrogen-vacancy center in diamond. We realize projective
measurements to prepare the multiple degrees of freedom of P1 centers - their
Jahn-Teller axis, nuclear spin and charge state - and exploit these to
selectively access multiple P1s in the bath. We develop control and single-shot
readout of the nuclear and electron spin, and use this to demonstrate an
entangled state of two P1 centers. These results provide a proof-of-principle
towards using dark electron-nuclear spin defects as qubits for quantum sensing,
computation and networks
Control of individual electron-spin pairs in an electron-spin bath
The decoherence of a central electron spin due to the dynamics of a coupled
electron-spin bath is a core problem in solid-state spin physics. Ensemble
experiments have studied the central spin coherence in detail, but such
experiments average out the underlying quantum dynamics of the bath. Here, we
show the coherent back-action of an individual NV center on an electron-spin
bath and use it to detect, prepare and control the dynamics of a pair of bath
spins. We image the NV-pair system with sub-nanometer resolution and reveal a
long dephasing time ( ms) for a qubit encoded in the
electron-spin pair. Our experiment reveals the microscopic quantum dynamics
that underlie the central spin decoherence and provides new opportunities for
controlling and sensing interacting spin systems
Mapping a 50-spin-qubit network through correlated sensing
Spins associated to optically accessible solid-state defects have emerged as
a versatile platform for exploring quantum simulation, quantum sensing and
quantum communication. Pioneering experiments have shown the sensing, imaging,
and control of multiple nuclear spins surrounding a single electron-spin
defect. However, the accessible size and complexity of these spin networks has
been constrained by the spectral resolution of current methods. Here, we map a
network of 50 coupled spins through high-resolution correlated sensing schemes,
using a single nitrogen-vacancy center in diamond. We develop concatenated
double-resonance sequences that identify spin-chains through the network. These
chains reveal the characteristic spin frequencies and their interconnections
with high spectral resolution, and can be fused together to map out the
network. Our results provide new opportunities for quantum simulations by
increasing the number of available spin qubits. Additionally, our methods might
find applications in nano-scale imaging of complex spin systems external to the
host crystal.Comment: 7 pages, 5 figure
Demonstration of entanglement-by-measurement of solid state qubits
Projective measurements are a powerful tool for manipulating quantum states.
In particular, a set of qubits can be entangled by measurement of a joint
property such as qubit parity. These joint measurements do not require a direct
interaction between qubits and therefore provide a unique resource for quantum
information processing with well-isolated qubits. Numerous schemes for
entanglement-by-measurement of solid-state qubits have been proposed, but the
demanding experimental requirements have so far hindered implementations. Here
we realize a two-qubit parity measurement on nuclear spins in diamond by
exploiting the electron spin of a nitrogen-vacancy center as readout ancilla.
The measurement enables us to project the initially uncorrelated nuclear spins
into maximally entangled states. By combining this entanglement with
high-fidelity single-shot readout we demonstrate the first violation of Bells
inequality with solid-state spins. These results open the door to a new class
of experiments in which projective measurements are used to create, protect and
manipulate entanglement between solid-state qubits.Comment: 6 pages, 4 figure
Experimental loophole-free violation of a Bell inequality using entangled electron spins separated by 1.3 km
For more than 80 years, the counterintuitive predictions of quantum theory
have stimulated debate about the nature of reality. In his seminal work, John
Bell proved that no theory of nature that obeys locality and realism can
reproduce all the predictions of quantum theory. Bell showed that in any local
realist theory the correlations between distant measurements satisfy an
inequality and, moreover, that this inequality can be violated according to
quantum theory. This provided a recipe for experimental tests of the
fundamental principles underlying the laws of nature. In the past decades,
numerous ingenious Bell inequality tests have been reported. However, because
of experimental limitations, all experiments to date required additional
assumptions to obtain a contradiction with local realism, resulting in
loopholes. Here we report on a Bell experiment that is free of any such
additional assumption and thus directly tests the principles underlying Bell's
inequality. We employ an event-ready scheme that enables the generation of
high-fidelity entanglement between distant electron spins. Efficient spin
readout avoids the fair sampling assumption (detection loophole), while the use
of fast random basis selection and readout combined with a spatial separation
of 1.3 km ensure the required locality conditions. We perform 245 trials
testing the CHSH-Bell inequality and find . A
null hypothesis test yields a probability of that a local-realist
model for space-like separated sites produces data with a violation at least as
large as observed, even when allowing for memory in the devices. This result
rules out large classes of local realist theories, and paves the way for
implementing device-independent quantum-secure communication and randomness
certification.Comment: Raw data will be made available after publicatio
Nanoantennas for visible and infrared radiation
Nanoantennas for visible and infrared radiation can strongly enhance the
interaction of light with nanoscale matter by their ability to efficiently link
propagating and spatially localized optical fields. This ability unlocks an
enormous potential for applications ranging from nanoscale optical microscopy
and spectroscopy over solar energy conversion, integrated optical
nanocircuitry, opto-electronics and density-ofstates engineering to
ultra-sensing as well as enhancement of optical nonlinearities. Here we review
the current understanding of optical antennas based on the background of both
well-developed radiowave antenna engineering and the emerging field of
plasmonics. In particular, we address the plasmonic behavior that emerges due
to the very high optical frequencies involved and the limitations in the choice
of antenna materials and geometrical parameters imposed by nanofabrication.
Finally, we give a brief account of the current status of the field and the
major established and emerging lines of investigation in this vivid area of
research.Comment: Review article with 76 pages, 21 figure
Plasmonic nanoparticle monomers and dimers: From nano-antennas to chiral metamaterials
We review the basic physics behind light interaction with plasmonic
nanoparticles. The theoretical foundations of light scattering on one metallic
particle (a plasmonic monomer) and two interacting particles (a plasmonic
dimer) are systematically investigated. Expressions for effective particle
susceptibility (polarizability) are derived, and applications of these results
to plasmonic nanoantennas are outlined. In the long-wavelength limit, the
effective macroscopic parameters of an array of plasmonic dimers are
calculated. These parameters are attributable to an effective medium
corresponding to a dilute arrangement of nanoparticles, i.e., a metamaterial
where plasmonic monomers or dimers have the function of "meta-atoms". It is
shown that planar dimers consisting of rod-like particles generally possess
elliptical dichroism and function as atoms for planar chiral metamaterials. The
fabricational simplicity of the proposed rod-dimer geometry can be used in the
design of more cost-effective chiral metamaterials in the optical domain.Comment: submitted to Appl. Phys.
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