Future Definition of the Candela Based on Single Photons

2021 ◽  
Vol 30 (3) ◽  
pp. 13-16
Author(s):  
Dong-Hoon LEE ◽  
Kee-Suk HONG
Keyword(s):  
Light Intensity ◽  
Single Photon ◽  
Primary Standard ◽  
Photon Counting ◽  
Radiant Flux ◽  
Single Photons ◽  
Recent Advances ◽  
Fixed Constant ◽  
Definition Of ◽  
Near Future

We discuss the candela (cd), the SI unit for light intensity, and its relation to single-photon technology. Currently, the definition of candela is based on the radiant flux in the unit of watts (W) with a fixed constant Kcd, and its primary standard is implemented electrically. Recent advances in the generation and the detection of a single photon indicate that photon-counting techniques with very small uncertainties of less than 1 ppm will become available in the near future. Thus single-photon technology will allow the light intensity to be defined simply in terms of the number of photons counted rather than the power measured in watts.

scholarly journals RR Lyrae stars: prime calibrators of the first rung of the distance ladder

2012 ◽  
Vol 8 (S289) ◽  
pp. 101-108 ◽  
Author(s):  
Carla Cacciari
Keyword(s):  
Local Group ◽  
Primary Standard ◽  
Empirical Methods ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
The Galaxy ◽  
Definition Of ◽  
Near Future ◽  
Lyrae Stars ◽  
Distance Indicators

AbstractRR Lyrae variables are the primary standard candles for old stellar populations, and the traditional first step in the definition of the distance scale. Their properties are known on the basis of well-established physical concepts and their calibration is based on several empirical methods. Both aspects are critically reviewed, and their application as distance indicators within the Galaxy and the Local Group are discussed, also in view of the observing facilities that will be available in the near future.

scholarly journals Dissecting and modeling zeaxanthin- and lutein-dependent nonphotochemical quenching in Arabidopsis thaliana

2017 ◽  
Vol 114 (33) ◽  
pp. E7009-E7017 ◽  
Author(s):  
Michelle Leuenberger ◽  
Jonathan M. Morris ◽  
Arnold M. Chan ◽  
Lauriebeth Leonelli ◽  
Krishna K. Niyogi ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Light Intensity ◽  
Vascular Plants ◽  
Single Photon ◽  
Photon Counting ◽  
Nonphotochemical Quenching ◽  
Light Acclimation ◽  
Single Photon Counting ◽  
Photosynthetic Organisms ◽  
Psbs Protein

Photosynthetic organisms use various photoprotective mechanisms to dissipate excess photoexcitation as heat in a process called nonphotochemical quenching (NPQ). Regulation of NPQ allows for a rapid response to changes in light intensity and in vascular plants, is primarily triggered by a pH gradient across the thylakoid membrane (∆pH). The response is mediated by the PsbS protein and various xanthophylls. Time-correlated single-photon counting (TCSPC) measurements were performed on Arabidopsis thaliana to quantify the dependence of the response of NPQ to changes in light intensity on the presence and accumulation of zeaxanthin and lutein. Measurements were performed on WT and mutant plants deficient in one or both of the xanthophylls as well as a transgenic line that accumulates lutein via an engineered lutein epoxide cycle. Changes in the response of NPQ to light acclimation in WT and mutant plants were observed between two successive light acclimation cycles, suggesting that the character of the rapid and reversible response of NPQ in fully dark-acclimated plants is substantially different from in conditions plants are likely to experience caused by changes in light intensity during daylight. Mathematical models of the response of zeaxanthin- and lutein-dependent reversible NPQ were constructed that accurately describe the observed differences between the light acclimation periods. Finally, the WT response of NPQ was reconstructed from isolated components present in mutant plants with a single common scaling factor, which enabled deconvolution of the relative contributions of zeaxanthin- and lutein-dependent NPQ.

Automated Quantum Entanglement and Cryptography for Networks of Robotic Systems

2021 ◽  
Author(s):  
Farbod Khoshnoud ◽  
Maziar Ghazinejad
Keyword(s):  
Mobile Robots ◽  
Quantum Entanglement ◽  
Quantum Control ◽  
Single Photon ◽  
Autonomous Systems ◽  
Photon Counting ◽  
Robotic Systems ◽  
Single Photons ◽  
Alignment Procedure ◽  
Automated Alignment

Abstract In this paper the procedure for automating the photon quantum experiments for mobile robotic applications is presented. Due to the rapid advances of quantum technologies and quantum engineering, the integration of quantum capabilities in robotic and autonomous systems will be inevitable, and therefore the study and investigation of compatibility and adaptability of quantum systems and classical autonomous systems is of great importance. In a quantum-classical hybrid setup, the source of single photon generation is placed on a leader robot which can send correlated single photons to robot followers. In the case of quantum entanglement, spontaneous parametric down-conversion process using nonlinear paired BBO crystals is implemented which sends entangled photons to the single photon counting modules installed on mobile robots. In the case of quantum cryptography, single photons are sent from Alice robot to Bob robot, where Alice has the course of single photon and Bob has a polarizing beamsplitter and two detectors and that can detect the polarization of photons as vertical and horizontal. Bob then can convert the polarizations to a digital signals as zeros and ones and use them as communication information for control purposes through a classical channel. Motorized optics equipment can automatically align the source of photons to detectors on the mobile robots. The automated alignment procedure is one of the key enabling technologies in integrating quantum capabilities with control of mobile robotic systems. In this paper, in particular, the automated alignment is studied while considering the uncertainties in the dynamic of the system which can potentially cause the alignment task very challenging. The uncertainty analysis in the automated alignment is implemented by Optimal Uncertainty Quantification technique to ensure achieving the quantum control of the robotic systems and presented here for the first time.

scholarly journals Harvesting entropy and quantifying the transition from noise to chaos in a photon-counting feedback loop

2015 ◽  
Vol 112 (30) ◽  
pp. 9258-9263 ◽  
Author(s):  
Aaron Morgan Hagerstrom ◽  
Thomas Edward Murphy ◽  
Rajarshi Roy
Keyword(s):  
Single Photon ◽  
Sampling Rate ◽  
Photon Counting ◽  
Random Number Generation ◽  
Optical Signal ◽  
Entropy Rate ◽  
Single Photons ◽  
Physical Mechanisms ◽  
Chaotic Laser ◽  
Long Timescales

Many physical processes, including the intensity fluctuations of a chaotic laser, the detection of single photons, and the Brownian motion of a microscopic particle in a fluid are unpredictable, at least on long timescales. This unpredictability can be due to a variety of physical mechanisms, but it is quantified by an entropy rate. This rate, which describes how quickly a system produces new and random information, is fundamentally important in statistical mechanics and practically important for random number generation. We experimentally study entropy generation and the emergence of deterministic chaotic dynamics from discrete noise in a system that applies feedback to a weak optical signal at the single-photon level. We show that the dynamics transition from shot noise to chaos as the photon rate increases and that the entropy rate can reflect either the deterministic or noisy aspects of the system depending on the sampling rate and resolution.

Ti/Au TES AS SUPERCONDUCTING DETECTOR FOR QUANTUM TECHNOLOGIES

2011 ◽  
Vol 09 (supp01) ◽  
pp. 405-413 ◽  
Author(s):  
L. LOLLI ◽  
G. BRIDA ◽  
I. P. DEGIOVANNI ◽  
M. GRAMEGNA ◽  
E. MONTICONE ◽  
...  
Keyword(s):  
Single Photon ◽  
Transition Edge Sensor ◽  
Photon Counting ◽  
Single Photons ◽  
Photon Detectors ◽  
Preliminary Measurement ◽  
Transition Edge ◽  
Visible Wavelength Range ◽  
Single Photon Detectors ◽  
Down Conversion

Single photon detectors are fundamental tools for quantum metrology, e.g. to calibrate both detectors and sources, as for quantum information. One of the most promising detectors able to resolve single photons is the transition-edge sensor (TES). We report our last results obtained with Ti/Au TES deposited on SiN substrate. Photon counting measurements, obtained by using pulsed sources, in the NIR-visible wavelength range, show the ability to resolve up to fourteen photons with an energy resolution of 0.44 eV at 690 nm (1.80 eV) and 0.38 eV at 1310 nm (0.95 eV), with a good linearity. A preliminary measurement obtained by using a parametric down conversion (PDC) heralded single photon source, at 812 nm (1.53 eV), is also reported.

Recent advances in time-correlated single-photon counting

2008 ◽  
Author(s):  
Felix Koberling ◽  
Benedikt Krämer ◽  
Sebastian Tannert ◽  
Steffen Rüttinger ◽  
Uwe Ortmann ◽  
...  
Keyword(s):  
Single Photon ◽  
Photon Counting ◽  
Single Photon Counting ◽  
Recent Advances

scholarly journals Protocol for generation of high-dimensional entanglement from an array of non-interacting photon emitters

2021 ◽  
Author(s):  
Thomas Bell ◽  
Jacob F F Bulmer ◽  
Alex Jones ◽  
Stefano Paesani ◽  
Dara McCutcheon ◽  
...  
Keyword(s):  
Quantum Key Distribution ◽  
Single Photon ◽  
High Dimensional ◽  
Single Photons ◽  
Time Resolved ◽  
Ghz States ◽  
Single Photon Emitters ◽  
Noise Resilience ◽  
The Impact ◽  
Near Future

Abstract Encoding high-dimensional quantum information into single photons can provide a variety of benefits for quantum technologies, such as improved noise resilience. However, the efficient generation of high-dimensional entanglement was thought to be out of reach for current and near-future photonic quantum technologies. We present a protocol for the near-deterministic generation of N-photon, d-dimensional photonic Greenberger-Horne-Zeilinger (GHZ) states using an array of d non-interacting single-photon emitters. We analyse the impact on performance of common sources of error for quantum emitters, such as photon spectral distinguishability and temporal mismatch, and find they are readily correctable with time-resolved detection to yield high fidelity GHZ states of multiple qudits. When applied to a quantum key distribution scenario, our protocol exhibits improved loss tolerance and key rates when increasing the dimensionality beyond binary encodings.

scholarly journals Photon-counting MCP/Timepix detectors for soft X-ray imaging and spectroscopic applications

2021 ◽  
Vol 28 (4) ◽  
Author(s):  
Anton S. Tremsin ◽  
John V. Vallerga ◽  
Oswald H. W. Siegmund ◽  
Justin Woods ◽  
Lance E. De Long ◽  
...  
Keyword(s):  
Single Photon ◽  
Photon Counting ◽  
Simultaneous Detection ◽  
Correlation Spectroscopy ◽  
Single Photons ◽  
X Ray ◽  
Detection Technology ◽  
X Ray Imaging ◽  
Multiple Particles ◽  
Event Rates

Detectors with microchannel plates (MCPs) provide unique capabilities to detect single photons with high spatial (<10 µm) and timing (<25 ps) resolution. Although this detection technology was originally developed for applications with low event rates, recent progress in readout electronics has enabled their operation at substantially higher rates by simultaneous detection of multiple particles. In this study, the potential use of MCP detectors with Timepix readout for soft X-ray imaging and spectroscopic applications where the position and time of each photon needs to be recorded is investigated. The proof-of-principle experiments conducted at the Advanced Light Source demonstrate the capabilities of MCP/Timepix detectors to operate at relatively high input counting rates, paving the way for the application of these detectors in resonance inelastic X-ray scattering and X-ray photon correlation spectroscopy (XPCS) applications. Local count rate saturation was investigated for the MCP/Timepix detector, which requires optimization of acquisition parameters for a specific scattering pattern. A single photon cluster analysis algorithm was developed to eliminate the charge spreading effects in the detector and increase the spatial resolution to subpixel values. Results of these experiments will guide the ongoing development of future MCP devices optimized for soft X-ray photon-counting applications, which should enable XPCS dynamics measurements down to sub-microsecond timescales.

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