40 research outputs found
Resonant driving of a single photon emitter embedded in a mechanical oscillator
Coupling a microscopic mechanical resonator to a nanoscale quantum system enables control of the mechanical resonator via the quantum system and vice-versa. The coupling is usually achieved through functionalization of the mechanical resonator, but this results in additional mass and dissipation channels. An alternative is an intrinsic coupling based on strain. Here we employ a monolithic semiconductor system: the nanoscale quantum system is a semiconductor quantum dot (QD) located inside a nanowire. We demonstrate the resonant optical driving of the QD transition in such a structure. The noise spectrum of the resonance fluorescence signal, recorded in the single-photon counting regime, reveals a coupling to mechanical modes of different types. We measure a sensitivity to displacement of 65 fm/root Hz limited by charge noise in the device. Finally, we use thermal excitation of the different modes to determine the location of the QD within the trumpet, and calculate the contribution of the Brownian motion to the dephasing of the emitter
An artificial Rb atom in a semiconductor with lifetime-limited linewidth
We report results important for the creation of a best-of-both-worlds quantum
hybrid system consisting of a solid-state source of single photons and an
atomic ensemble as quantum memory. We generate single photons from a GaAs
quantum dot (QD) frequency-matched to the Rb D2-transitions and then use the Rb
transitions to analyze spectrally the quantum dot photons. We demonstrate
lifetime-limited QD linewidths (1.48 GHz) with both resonant and non-resonant
excitation. The QD resonance fluorescence in the low power regime is dominated
by Rayleigh scattering, a route to match quantum dot and Rb atom linewidths and
to shape the temporal wave packet of the QD photons. Noise in the solid-state
environment is relatively benign: there is a blinking of the resonance
fluorescence at MHz rates but negligible upper state dephasing of the QD
transition. We therefore establish a close-to-ideal solid-state source of
single photons at a key wavelength for quantum technologies
A quantum sensing metrology for magnetic memories
Magnetic random access memory (MRAM) is a leading emergent memory technology
that is poised to replace current non-volatile memory technologies such as
eFlash. However, the scaling of MRAM technologies is heavily affected by
device-to-device variability rooted in the stochastic nature of the MRAM
writing process into nanoscale magnetic layers. Here, we introduce a
non-contact metrology technique deploying Scanning NV Magnetometry (SNVM) to
investigate MRAM performance at the individual bit level. We demonstrate
magnetic reversal characterization in individual, < 60 nm sized bits, to
extract key magnetic properties, thermal stability, and switching statistics,
and thereby gauge bit-to-bit uniformity. We showcase the performance of our
method by benchmarking two distinct bit etching processes immediately after
pattern formation. Unlike previous methods, our approach unveils marked
differences in switching behaviour of fully contacted MRAM devices stemming
from these processes. Our findings highlight the potential of nanoscale quantum
sensing of MRAM devices for early-stage screening in the processing line,
paving the way for future incorporation of this nanoscale characterization tool
in the semiconductor industry
Dielectric GaAs Antenna Ensuring an Efficient Broadband Coupling between an InAs Quantum Dot and a Gaussian Optical Beam
We introduce the photonic trumpet, a dielectric structure which ensures a
nearly perfect coupling between an embedded quantum light source and a Gaussian
free-space beam. A photonic trumpet exploits both the broadband spontaneous
emission control provided by a single-mode photonic wire and the adiabatic
expansion of this mode within a conical taper. Numerical simulations highlight
the outstanding performance and robustness of this concept. As a first
application in the field of quantum optics, we report the realisation of an
ultra-bright single-photon source. The device, a GaAs photonic trumpet
containing few InAs quantum dots, demonstrates a first-lens external efficiency
of
A fiber-coupled quantum-dot on a photonic tip
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