Spectroscopy in the visible and near-infrared has been the main tool for characterising the surfa... more Spectroscopy in the visible and near-infrared has been the main tool for characterising the surface properties of asteroids for decades. For a given target, the two wavelength regimes are usually acquired by different telescopes/instruments, separated by years. They are seldom obtained simultaneously. However, it is not straightforward to combine datasets from different sources because of the spectral reddening linked with phase angle. We present the first-light result of SOVAG (Spectrographe pour l'Observations dans le Visible et infrarouge proche d'Astéroïdes Géocroiseurs), a new concept of spectrograph for observing both wavelength ranges at the same time. It is compact in design and portable. We developed a prototype of this instrument between 2016 and 2018. In July 2018, we mounted SOVAG on the 1 m-telescope in Pic du Midi observatory (for which it was designed) and conducted its on-sky first light experiment. We present a spectrum of (4) Vesta which demonstrates the reliability of observations and the accuracy of the calibration. Ongoing development will allow us to push observation-limits toward fainter objects.
Image (left) acquired using a camera which active layer is a photoconductive layer fabricated fro... more Image (left) acquired using a camera which active layer is a photoconductive layer fabricated from a HgTe nanocrystal film (schematic on right).
The invention relates to a digital signal acquisition device comprising a sensor (10) of analog s... more The invention relates to a digital signal acquisition device comprising a sensor (10) of analog signal, a digital analog converter (12) supplying a digital sample of the analog signal and filtering means (16) of this digital sample. Such a device also comprises: - means (13) for estimating a value of the analog signal from the digital sample; - means (14) for determining a factor N over-sampling of the analog signal from the estimated value and a predetermined threshold noise control where N is an integer greater than or equal to 1; - means (15) for sampling the analog signal activated factor N if N> 1. The filtering means are then able to filter N digital samples of the analog signal delivered by the analogue digital converter, so as to reduce the electronic noise affecting the signal.
Proceedings of the 11th International Conference on Distributed Smart Cameras, 2017
This paper presents a new method based on Non Destructive Readout (NDRO) to improve multi-exposur... more This paper presents a new method based on Non Destructive Readout (NDRO) to improve multi-exposure High Dynamic Range (HDR) Imaging. A sequence of Low-Dynamic Range (LDR) images can then be acquired during a single exposure. The concept enables the latency between LDR images to be removed as well as the intrinsic ghost artifacts observed using state-of-art HDR systems based on multi-exposures. The method has been applied to improve the performances of HDR sensor based on logarithmic pixels. Using the NDRO method, a Short Wave InfraRed (SWIR) camera has been designed to produce HDR IR videos. A real-time HDR video stream generation is achieved based on GPU implantation.
We present an experimental and theoretical study of the existence of acoustic phonon sidebands in... more We present an experimental and theoretical study of the existence of acoustic phonon sidebands in the emission line of single self-assembled InAs/GaAs quantum dots. Temperature-dependent photoluminescence measurements reveal a deviation from a Lorentzian profile with the appearance of lateral sidebands. We obtain an excellent agreement with calculations done in the framework of the Huang-Rhys formalism. We conclude that the only relevant parameter for the observation of acoustic phonon sidebands is the linewidth of the central zero-phonon line. At high temperature, the quasi-Lorentzian quantum dot line appears to be fully determined by the acoustic phonon sidebands.
Until three years ago we only used monochromator systems with an APD coupled to a spectrometer fo... more Until three years ago we only used monochromator systems with an APD coupled to a spectrometer for optical detection. For example, in our single Quantum Dot (QD) spectroscopy experimental set-up signal detection was performed, after spectral filtering by a 32 cm monochromator, ...
Making a system state follow a prescribed trajectory despite fluctuations and errors commonly con... more Making a system state follow a prescribed trajectory despite fluctuations and errors commonly consists of monitoring an observable (temperature, blood-glucose level, etc.) and reacting on its controllers (heater power, insulin amount, etc.). In the quantum domain, there is a change of paradigm in feedback, since measurements modify the state of the system, most dramatically when the trajectory goes through superpositions of measurement eigenstates. Here, we demonstrate the stabilization of an arbitrary trajectory of a superconducting qubit by measurement-based feedback. The protocol benefits from the long coherence time (T 2 > 10 s) of the 3D transmon qubit, the high efficiency (82%) of the phasepreserving Josephson amplifier, and fast electronics that ensure less than 500 ns total delay. At discrete time intervals, the state of the qubit is measured and corrected in case an error is detected. For Rabi oscillations, where the discrete measurements occur when the qubit is supposed to be in the measurement pointer states, we demonstrate an average fidelity of 85% to the targeted trajectory. For Ramsey oscillations, which do not go through pointer states, the average fidelity reaches 76%. Incidentally, we demonstrate a fast reset protocol that allows us to cool a 3D transmon qubit down to 0:6% in the excited state.
Physica E: Low-dimensional Systems and Nanostructures, 2004
We report the ÿrst direct observation of Huang-Rhys side-bands in the photoluminescence spectrum ... more We report the ÿrst direct observation of Huang-Rhys side-bands in the photoluminescence spectrum of a single InAs/GaAs quantum dot (QD). At low temperature (10 K) the single QD spectrum has a quasi-Lorentzian proÿle. At higher temperatures, we observe a strong deviation from a Lorentzian proÿle with the appearance of asymmetric side-bands which become symmetric above 70 K. We obtain an excellent agreement with theoretical calculations done in the framework of the Huang-Rhys formalism. We conclude that the zero-phonon linewidth is the relevant parameter for the observation of the low-energy acoustic phonon side-bands.
Making a system state follow a prescribed trajectory despite fluctuations and errors commonly con... more Making a system state follow a prescribed trajectory despite fluctuations and errors commonly consists in monitoring an observable (temperature, blood-glucose level. . .) and reacting on its controllers (heater power, insulin amount. . .). In the quantum domain, there is a change of paradigm in feedback since measurements modify the state of the system, most dramatically when the trajectory goes through superpositions of measurement eigenstates. Here, we demonstrate the stabilization of an arbitrary trajectory of a superconducting qubit by measurement based feedback. The protocol benefits from the long coherence time (T2 > 10 µs) of the 3D transmon qubit, the high efficiency (82%) of the phase preserving Josephson amplifier, and fast electronics ensuring less than 500 ns total delay. At discrete time intervals, the state of the qubit is measured and corrected in case an error is detected. For Rabi oscillations, where the discrete measurements occur when the qubit is supposed to be in the measurement pointer states, we demonstrate an average fidelity of 85% to the targeted trajectory. For Ramsey oscillations, which does not go through pointer states, the average fidelity reaches 76%. Incidentally, we demonstrate a fast reset protocol allowing to cool a 3D transmon qubit down to 0.6% in the excited state.
... Jean-Luc Gach1, David Darson2, Christian Guillaume3, Michel Goillandeau3, Olivier Boissin1, J... more ... Jean-Luc Gach1, David Darson2, Christian Guillaume3, Michel Goillandeau3, Olivier Boissin1, Jacques Boulesteix1, Cyril Cavadore4 1Observatoire de Marseille, 2Laboratoire de Physique et de la Matière Condensée, 3Observatoire de Haute Provence ... skipper outputs. Page 8. ...
We present the experimental evidence of giant optical anisotropy in single InAs quantum dots. Pol... more We present the experimental evidence of giant optical anisotropy in single InAs quantum dots. Polarization-resolved photoluminescence spectroscopy reveals a linear polarization ratio with huge fluctuations, from one quantum dot to another, in sign and in magnitude with absolute values up to 82%. Systematic measurements on hundreds of quantum dots coming from two different laboratories demonstrate that the giant optical anisotropy is an intrinsic feature of dilute quantumdot arrays.
Spectroscopy in the visible and near-infrared has been the main tool for characterising the surfa... more Spectroscopy in the visible and near-infrared has been the main tool for characterising the surface properties of asteroids for decades. For a given target, the two wavelength regimes are usually acquired by different telescopes/instruments, separated by years. They are seldom obtained simultaneously. However, it is not straightforward to combine datasets from different sources because of the spectral reddening linked with phase angle. We present the first-light result of SOVAG (Spectrographe pour l'Observations dans le Visible et infrarouge proche d'Astéroïdes Géocroiseurs), a new concept of spectrograph for observing both wavelength ranges at the same time. It is compact in design and portable. We developed a prototype of this instrument between 2016 and 2018. In July 2018, we mounted SOVAG on the 1 m-telescope in Pic du Midi observatory (for which it was designed) and conducted its on-sky first light experiment. We present a spectrum of (4) Vesta which demonstrates the reliability of observations and the accuracy of the calibration. Ongoing development will allow us to push observation-limits toward fainter objects.
Image (left) acquired using a camera which active layer is a photoconductive layer fabricated fro... more Image (left) acquired using a camera which active layer is a photoconductive layer fabricated from a HgTe nanocrystal film (schematic on right).
The invention relates to a digital signal acquisition device comprising a sensor (10) of analog s... more The invention relates to a digital signal acquisition device comprising a sensor (10) of analog signal, a digital analog converter (12) supplying a digital sample of the analog signal and filtering means (16) of this digital sample. Such a device also comprises: - means (13) for estimating a value of the analog signal from the digital sample; - means (14) for determining a factor N over-sampling of the analog signal from the estimated value and a predetermined threshold noise control where N is an integer greater than or equal to 1; - means (15) for sampling the analog signal activated factor N if N> 1. The filtering means are then able to filter N digital samples of the analog signal delivered by the analogue digital converter, so as to reduce the electronic noise affecting the signal.
Proceedings of the 11th International Conference on Distributed Smart Cameras, 2017
This paper presents a new method based on Non Destructive Readout (NDRO) to improve multi-exposur... more This paper presents a new method based on Non Destructive Readout (NDRO) to improve multi-exposure High Dynamic Range (HDR) Imaging. A sequence of Low-Dynamic Range (LDR) images can then be acquired during a single exposure. The concept enables the latency between LDR images to be removed as well as the intrinsic ghost artifacts observed using state-of-art HDR systems based on multi-exposures. The method has been applied to improve the performances of HDR sensor based on logarithmic pixels. Using the NDRO method, a Short Wave InfraRed (SWIR) camera has been designed to produce HDR IR videos. A real-time HDR video stream generation is achieved based on GPU implantation.
We present an experimental and theoretical study of the existence of acoustic phonon sidebands in... more We present an experimental and theoretical study of the existence of acoustic phonon sidebands in the emission line of single self-assembled InAs/GaAs quantum dots. Temperature-dependent photoluminescence measurements reveal a deviation from a Lorentzian profile with the appearance of lateral sidebands. We obtain an excellent agreement with calculations done in the framework of the Huang-Rhys formalism. We conclude that the only relevant parameter for the observation of acoustic phonon sidebands is the linewidth of the central zero-phonon line. At high temperature, the quasi-Lorentzian quantum dot line appears to be fully determined by the acoustic phonon sidebands.
Until three years ago we only used monochromator systems with an APD coupled to a spectrometer fo... more Until three years ago we only used monochromator systems with an APD coupled to a spectrometer for optical detection. For example, in our single Quantum Dot (QD) spectroscopy experimental set-up signal detection was performed, after spectral filtering by a 32 cm monochromator, ...
Making a system state follow a prescribed trajectory despite fluctuations and errors commonly con... more Making a system state follow a prescribed trajectory despite fluctuations and errors commonly consists of monitoring an observable (temperature, blood-glucose level, etc.) and reacting on its controllers (heater power, insulin amount, etc.). In the quantum domain, there is a change of paradigm in feedback, since measurements modify the state of the system, most dramatically when the trajectory goes through superpositions of measurement eigenstates. Here, we demonstrate the stabilization of an arbitrary trajectory of a superconducting qubit by measurement-based feedback. The protocol benefits from the long coherence time (T 2 > 10 s) of the 3D transmon qubit, the high efficiency (82%) of the phasepreserving Josephson amplifier, and fast electronics that ensure less than 500 ns total delay. At discrete time intervals, the state of the qubit is measured and corrected in case an error is detected. For Rabi oscillations, where the discrete measurements occur when the qubit is supposed to be in the measurement pointer states, we demonstrate an average fidelity of 85% to the targeted trajectory. For Ramsey oscillations, which do not go through pointer states, the average fidelity reaches 76%. Incidentally, we demonstrate a fast reset protocol that allows us to cool a 3D transmon qubit down to 0:6% in the excited state.
Physica E: Low-dimensional Systems and Nanostructures, 2004
We report the ÿrst direct observation of Huang-Rhys side-bands in the photoluminescence spectrum ... more We report the ÿrst direct observation of Huang-Rhys side-bands in the photoluminescence spectrum of a single InAs/GaAs quantum dot (QD). At low temperature (10 K) the single QD spectrum has a quasi-Lorentzian proÿle. At higher temperatures, we observe a strong deviation from a Lorentzian proÿle with the appearance of asymmetric side-bands which become symmetric above 70 K. We obtain an excellent agreement with theoretical calculations done in the framework of the Huang-Rhys formalism. We conclude that the zero-phonon linewidth is the relevant parameter for the observation of the low-energy acoustic phonon side-bands.
Making a system state follow a prescribed trajectory despite fluctuations and errors commonly con... more Making a system state follow a prescribed trajectory despite fluctuations and errors commonly consists in monitoring an observable (temperature, blood-glucose level. . .) and reacting on its controllers (heater power, insulin amount. . .). In the quantum domain, there is a change of paradigm in feedback since measurements modify the state of the system, most dramatically when the trajectory goes through superpositions of measurement eigenstates. Here, we demonstrate the stabilization of an arbitrary trajectory of a superconducting qubit by measurement based feedback. The protocol benefits from the long coherence time (T2 > 10 µs) of the 3D transmon qubit, the high efficiency (82%) of the phase preserving Josephson amplifier, and fast electronics ensuring less than 500 ns total delay. At discrete time intervals, the state of the qubit is measured and corrected in case an error is detected. For Rabi oscillations, where the discrete measurements occur when the qubit is supposed to be in the measurement pointer states, we demonstrate an average fidelity of 85% to the targeted trajectory. For Ramsey oscillations, which does not go through pointer states, the average fidelity reaches 76%. Incidentally, we demonstrate a fast reset protocol allowing to cool a 3D transmon qubit down to 0.6% in the excited state.
... Jean-Luc Gach1, David Darson2, Christian Guillaume3, Michel Goillandeau3, Olivier Boissin1, J... more ... Jean-Luc Gach1, David Darson2, Christian Guillaume3, Michel Goillandeau3, Olivier Boissin1, Jacques Boulesteix1, Cyril Cavadore4 1Observatoire de Marseille, 2Laboratoire de Physique et de la Matière Condensée, 3Observatoire de Haute Provence ... skipper outputs. Page 8. ...
We present the experimental evidence of giant optical anisotropy in single InAs quantum dots. Pol... more We present the experimental evidence of giant optical anisotropy in single InAs quantum dots. Polarization-resolved photoluminescence spectroscopy reveals a linear polarization ratio with huge fluctuations, from one quantum dot to another, in sign and in magnitude with absolute values up to 82%. Systematic measurements on hundreds of quantum dots coming from two different laboratories demonstrate that the giant optical anisotropy is an intrinsic feature of dilute quantumdot arrays.
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Papers by david darson