27 research outputs found
Piezospectroscopic measurement of high-frequency vibrations in a pulse-tube cryostat
Vibrations in cryocoolers are a recurrent concern to the end user. They
appear in different parts of the acoustic spectrum depending on the
refrigerator type, Gifford McMahon or pulse-tube, and with a variable coupling
strength to the physical system under interest. Here, we use the
piezospectroscopic effect in rare-earth doped crystals at low temperature as a
high resolution, contact-less probe for the vibrations. With this optical
spectroscopic technique, we obtain and analyze the vibration spectrum up to
700kHz of a 2kW pulse-tube cooler. We attempt an absolute calibration based on
known experimental parameters to make our method partially quantitative and to
provide a possible comparison with other well-established techniques
Quantum memory for light: large efficiency at telecom wavelength
We implement the ROSE protocol in an erbium doped solid, compatible with the
telecom range. The ROSE scheme is an adaptation of the standard 2-pulse photon
echo to make it suitable for a quantum memory. We observe an efficiency of 40%
in a forward direction by using specific orientations of the light
polarizations, magnetic field and crystal axes
Selective optical addressing of nuclear spins through superhyperfine interaction in rare-earth doped solids
In Er:YSiO, we demonstrate the selective optical addressing of
the Y nuclear spins through their superhyperfine coupling with
the Er electronic spins possessing large Land\'e -factors. We
experimentally probe the electron-nuclear spin mixing with photon echo
techniques and validate our model. The site-selective optical addressing of the
Y nuclear spins is designed by adjusting the magnetic field strength and
orientation. This constitutes an important step towards the realization of
long-lived solid-state qubits optically addressed by telecom photons.Comment: 5 pages, 4 figures, supplementary material (3 pages
Optical memory bandwidth and multiplexing capacity in the erbium telecommunication window
We study the bandwidth and multiplexing capacity of an erbium-doped optical
memory for quantum storage purposes. We concentrate on the protocol ROSE
(Revival of a Silenced Echo) because it has the largest potential multiplexing
capacity. Our analysis is applicable to other protocols that involve strong
optical excitation. We show that the memory performance is limited by
instantaneous spectral diffusion and we describe how this effect can be
minimised to achieve optimal performance
Time reversal of light by linear dispersive filtering near atomic resonance
Based on the similarity of paraxial diffraction and dispersion mathematical
descriptions, the temporal imaging of optical pulses combines linear dispersive
filters and quadratic phase modulations operating as time lenses. We consider
programming a dispersive filter near atomic resonance in rare earth ion doped
crystals, which leads to unprecedented high values of dispersive power. This
filter is used in an approximate imaging scheme, combining a single time lens
and a single dispersive section and operating as a time reversing device, with
potential applications in radio-frequency signal processing. This scheme is
closely related to three-pulse photon echo with chirped pulses but the
connection with temporal imaging and dispersive filtering emphasizes new
features.Comment: 21 pages, 11 figure
Ultrasound modulated optical tomography in scattering media: flux filtering based on persistent spectral hole burning in the optical diagnosis window
Ultrasound modulated optical tomography (UOT) is a powerful imaging technique
to discriminate healthy from unhealthy biological tissues based on their
optical signature. Among the numerous detection techniques developed for
acousto-optic imaging, only those based on spectral filtering are intrinsically
immune to speckle decorrelation. This paper reports on UOT imaging based on
spectral hole burning in Tm:YAG crystal under a moderate magnetic field (200G)
with a well-defined orientation. The deep and long-lasting holes translate into
a more efficient UOT imaging with a higher contrast and faster imaging frame
rate. We demonstrate the potential of this method by imaging calibrated phantom
scattering gels.Comment: 4 pages, 5 figure
20 GHz instantaneous bandwidth RF spectrum analyzer with high time-resolution
International audienceWe report on the experimental demonstration of a multi-gigahertz bandwidth RF spectrum analyzer exhibiting a resolution below 20 MHz, based on spectral hole burning in a rare-earth ion-doped crystal. To be compatible with demanding real-time spectrum monitoring applications, our demonstrator is designed to reach a high time resolution. For this purpose, we implemented the so-called "rainbow" architecture in which the spectral components of the incoming signal are angularly separated by the crystal, and are then acquired with a pixelated photodetector. The Tm 3+ :YAG crystal is programmed with a semiconductor DFB laser which frequency scan is servo-controlled and synchronized with the angular scan of a resonant galvanometric mirror, while a high-speed camera is used to acquire the spectra. In the perspective of future implementation within a system, the crystal is cooled below 4 K with a closed-cycle cryostat. With this setup, we have been able to monitor and record the spectrum of complex microwave signals over an instantaneous bandwidth above 20 GHz, with a time resolution below 100 µs, 400 resolvable frequency components and a probability of intercept of 100 %
Limits to the sensitivity of a rare-earth-enabled cryogenic vibration sensor
International audienceCryogenics is a pivotal aspect in the development of quantum technologies. Closed-cycle devices have recently emerged as an environmentally friendly and low-maintenance alternative to liquid helium cryostats. Yet the larger level of vibrations in dry cryocoolers forbids their use in most sensitive applications. In a recent work, we have proposed an inertial, broadband, contactless sensor based on the piezospectroscopic effect, i.e., the natural sensitivity of optical lines to strain exhibited by impurities in solids. This sensor builds on the exceptional spectroscopic properties of rare earth ions and operates below 4 K, where spectral hole burning considerably enhances the sensitivity. In this paper, we investigate the fundamental and technical limitations of this vibration sensor by comparing a rigid sample attachment to the cold stage of a pulse-tube cryocooler and a custom-designed exchange gas chamber for acoustic isolation
Limits to the sensitivity of a rare-earth-enabled cryogenic vibration sensor
International audienceCryogenics is a pivotal aspect in the development of quantum technologies. Closed-cycle devices have recently emerged as an environmentally friendly and low-maintenance alternative to liquid helium cryostats. Yet the larger level of vibrations in dry cryocoolers forbids their use in most sensitive applications. In a recent work, we have proposed an inertial, broadband, contactless sensor based on the piezospectroscopic effect, i.e., the natural sensitivity of optical lines to strain exhibited by impurities in solids. This sensor builds on the exceptional spectroscopic properties of rare earth ions and operates below 4 K, where spectral hole burning considerably enhances the sensitivity. In this paper, we investigate the fundamental and technical limitations of this vibration sensor by comparing a rigid sample attachment to the cold stage of a pulse-tube cryocooler and a custom-designed exchange gas chamber for acoustic isolation