scholarly journals Spatial Wavefunction Characterization of Femtosecond Pulses at Single-Photon Level

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Billy Lam ◽  
Mohamed ElKabbash ◽  
Jihua Zhang ◽  
Chunlei Guo
Keyword(s):  
Light Source ◽  
Continuous Wave ◽  
Single Photon ◽  
Quantum Tomography ◽  
Measurement Procedure ◽  
Single Photons ◽  
Wave Source ◽  
Temporal Mode ◽  
Measurement Approach

Reading quantum information of single photons is commonly realized by quantum tomography or the direct (weak) measurement approach. However, these methods are time-consuming and face enormous challenges in characterizing single photons from an ultrafast light source due to the stringent temporal mode matching requirements. Here, we retrieve the spatial wavefunction of indistinguishable single photons from both a continuous wave source and a femtosecond light source using a self-referencing interferometer. Our method only requires nine ensemble-averaged measurements. This technique simplifies the measurement procedure of single-photon wavefunction and automatically mode matches each self-interfering single photon temporally, which enables the measurement of the spatial wavefunction of single photons from an ultrafast light source.

scholarly journals NUMERICAL CHARACTERIZATION OF ATMOSPHERIC EFFECTS ON AN EARTH–SPACE QUANTUM COMMUNICATION CHANNEL

2007 ◽  
Vol 05 (01n02) ◽  
pp. 241-248 ◽  
Author(s):  
N. ANTONIETTI ◽  
M. MONDIN ◽  
G. BRIDA ◽  
M. GENOVESE
Keyword(s):  
Free Space ◽  
Communication Channel ◽  
Quantum Communication ◽  
Single Photon ◽  
Atmospheric Effects ◽  
Single Photons ◽  
Atmospheric Conditions ◽  
Numerical Characterization ◽  
Simulation Results

Quantum communication in free space is the next challenge of telecommunications. Since we want to determine the outcome of a quantum communication by means of single photons, we must understand how a single photon interacts with the atmosphere. In this brief article, some simulation results for realistic and generic atmospheric conditions are reported and discussed.

scholarly journals Self-referenced hologram of a single photon beam

Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 516
Author(s):  
Wiktor Szadowiak ◽  
Sanjukta Kundu ◽  
Jerzy Szuniewicz ◽  
Radek Lapkiewicz
Keyword(s):  
Phase Measurement ◽  
Single Photon ◽  
Spatial Filter ◽  
Complete Characterization ◽  
Single Photons ◽  
Quantitative Characterization ◽  
Interferometric Technique ◽  
Spatial Phase ◽  
Photon Source

Quantitative characterization of the spatial structure of single photons is essential for free-space quantum communication and quantum imaging. We introduce an interferometric technique that enables the complete characterization of a two-dimensional probability amplitude of a single photon. Importantly, in contrast to methods that use a reference photon for the phase measurement, our technique relies on a single photon interfering with itself. Our setup comprises of a heralded single-photon source with an unknown spatial phase and a modified Mach-Zehnder interferometer with a spatial filter in one of its arms. The spatial filter removes the unknown spatial phase and the filtered beam interferes with the unaltered beam passing through the other arm of the interferometer. We experimentally confirm the feasibility of our technique by reconstructing the spatial phase of heralded single photons using the lowest order interference fringes. This technique can be applied to the characterization of arbitrary pure spatial states of single photons.

scholarly journals Noise and Breakdown Characterization of SPAD Detectors with Time-Gated Photon-Counting Operation

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5287
Author(s):  
Hiwa Mahmoudi ◽  
Michael Hofbauer ◽  
Bernhard Goll ◽  
Horst Zimmermann
Keyword(s):  
Breakdown Voltage ◽  
Single Photon ◽  
Photon Counting ◽  
Low Noise ◽  
Dark Count ◽  
Fully Integrated ◽  
Trade Offs ◽  
And Performance ◽  
Noise Models

Being ready-to-detect over a certain portion of time makes the time-gated single-photon avalanche diode (SPAD) an attractive candidate for low-noise photon-counting applications. A careful SPAD noise and performance characterization, however, is critical to avoid time-consuming experimental optimization and redesign iterations for such applications. Here, we present an extensive empirical study of the breakdown voltage, as well as the dark-count and afterpulsing noise mechanisms for a fully integrated time-gated SPAD detector in 0.35-μm CMOS based on experimental data acquired in a dark condition. An “effective” SPAD breakdown voltage is introduced to enable efficient characterization and modeling of the dark-count and afterpulsing probabilities with respect to the excess bias voltage and the gating duration time. The presented breakdown and noise models will allow for accurate modeling and optimization of SPAD-based detector designs, where the SPAD noise can impose severe trade-offs with speed and sensitivity as is shown via an example.

Mechanical Characterization of UV Photopolymerized PMMA with Different Photo-Initiator Concentration

2021 ◽  
Vol 903 ◽  
pp. 11-16
Author(s):  
M.A. Manjunath ◽  
K. Naveen ◽  
Prakash Vinod ◽  
N. Balashanmugam ◽  
M.R. Shankar
Keyword(s):  
Mechanical Properties ◽  
Light Source ◽  
Polymethyl Methacrylate ◽  
Biomedical Applications ◽  
Mechanical Characterization ◽  
Uv Light ◽  
Curing Time ◽  
Uv Led ◽  
Pmma Resin

Polymethyl methacrylate (PMMA) is one among few known photo-polymeric resin useful in lithography for fabricating structures having better mechanical properties to meet the requirement in electronics and biomedical applications. This study explores the effect of Photo Initiator (PI) concentration and also curing time on strength and hardness of Polymethyl methacrylate (PMMA) obtained by UV photopolymerization of Methyl methacrylate (MMA) monomer. The UV LED light source operating at the wavelength of 364 nm is used with Benzoin Ethyl Ether (BEE) as photo initiator. The curing of PMMA resin is supported with peltier cooling device placed at the bottom of the UV light source. The characterisation study of UV photo cured PMMA is analysed through nano indenter (Agilent Technologies-G200). The current work investigates the influence of PI concentration and curing time in achieving maximum mechanical properties for UV photopolymerized PMMA.

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