scholarly journals Behavioural and physiological limits to vision in mammals

2017 ◽  
Vol 372 (1717) ◽  
pp. 20160072 ◽  
Author(s):  
Greg D. Field ◽  
Alapakkam P. Sampath
Keyword(s):  
Single Photon ◽  
Signal Transmission ◽  
High Sensitivity ◽  
Human Vision ◽  
Past Century ◽  
Single Photons ◽  
Rod Photoreceptors ◽  
Physiological Limits ◽  
Visual Threshold ◽  
Behavioural Experiments

Human vision is exquisitely sensitive—a dark-adapted observer is capable of reliably detecting the absorption of a few quanta of light. Such sensitivity requires that the sensory receptors of the retina, rod photoreceptors, generate a reliable signal when single photons are absorbed. In addition, the retina must be able to extract this information and relay it to higher visual centres under conditions where very few rods signal single-photon responses while the majority generate only noise. Critical to signal transmission are mechanistic optimizations within rods and their dedicated retinal circuits that enhance the discriminability of single-photon responses by mitigating photoreceptor and synaptic noise. We describe behavioural experiments over the past century that have led to the appreciation of high sensitivity near absolute visual threshold. We further consider mechanisms within rod photoreceptors and dedicated rod circuits that act to extract single-photon responses from cellular noise. We highlight how these studies have shaped our understanding of brain function and point out several unresolved questions in the processing of light near the visual threshold. This article is part of the themed issue ‘Vision in dim light’.

scholarly journals The discovery of the ability of rod photoreceptors to signal single photons

2018 ◽  
Vol 150 (3) ◽  
pp. 383-388 ◽  
Author(s):  
Edward N. Pugh
Keyword(s):  
Visual System ◽  
Molecular Mechanism ◽  
Single Photon ◽  
Visual Environment ◽  
Single Photons ◽  
Rod Photoreceptors ◽  
Subsequent Research ◽  
Visual Threshold ◽  
Reliable Transmission

Vertebrate rod photoreceptors evolved the astonishing ability to respond reliably to single photons. In parallel, the proximate neurons of the visual system evolved the ability to reliably encode information from a few single-photon responses (SPRs) as arising from the presence of an object of interest in the visual environment. These amazing capabilities were first inferred from measurements of human visual threshold by Hecht et al. (1942), whose paper has since been cited over 1,000 times. Subsequent research, in part inspired by Hecht et al.’s discovery, has directly measured rod SPRs, characterized the molecular mechanism responsible for their generation, and uncovered much about the specializations in the retina that enable the reliable transmission of SPRs in the teeth of intrinsic neuronal noise.

Signal coding in cockroach photoreceptors is tuned to dim environments

2012 ◽  
Vol 108 (10) ◽  
pp. 2641-2652 ◽  
Author(s):  
K. Heimonen ◽  
E.-V. Immonen ◽  
R. V. Frolov ◽  
I. Salmela ◽  
M. Juusola ◽  
...  
Keyword(s):  
Information Transfer ◽  
Periplaneta Americana ◽  
Single Photon ◽  
Signal To Noise Ratio ◽  
Temporal Integration ◽  
High Sensitivity ◽  
Single Photons ◽  
Low Frequencies ◽  
Whole Cell Patch Clamp ◽  
High Level

In dim light, scarcity of photons typically leads to poor vision. Nonetheless, many animals show visually guided behavior with dim environments. We investigated the signaling properties of photoreceptors of the dark active cockroach ( Periplaneta americana) using intracellular and whole-cell patch-clamp recordings to determine whether they show selective functional adaptations to dark. Expectedly, dark-adapted photoreceptors generated large and slow responses to single photons. However, when light adapted, responses of both phototransduction and the nontransductive membrane to white noise (WN)-modulated stimuli remained slow with corner frequencies ∼20 Hz. This promotes temporal integration of light inputs and maintains high sensitivity of vision. Adaptive changes in dynamics were limited to dim conditions. Characteristically, both step and frequency responses stayed effectively unchanged for intensities >1,000 photons/s/photoreceptor. A signal-to-noise ratio (SNR) of the light responses was transiently higher at frequencies <5 Hz for ∼5 s after light onset but deteriorated to a lower value upon longer stimulation. Naturalistic light stimuli, as opposed to WN, evoked markedly larger responses with higher SNRs at low frequencies. This allowed realistic estimates of information transfer rates, which saturated at ∼100 bits/s at low-light intensities. We found, therefore, selective adaptations beneficial for vision in dim environments in cockroach photoreceptors: large amplitude of single-photon responses, constant high level of temporal integration of light inputs, saturation of response properties at low intensities, and only transiently efficient encoding of light contrasts. The results also suggest that the sources of the large functional variability among different photoreceptors reside mostly in phototransduction processes and not in the properties of the nontransductive membrane.

Transmission of single photon signals through a binary synapse in the mammalian retina

2004 ◽  
Vol 21 (5) ◽  
pp. 693-702 ◽  
Author(s):  
AMY BERNTSON ◽  
ROBERT G. SMITH ◽  
W. ROWLAND TAYLOR
Keyword(s):  
Ganglion Cells ◽  
Single Photon ◽  
Bipolar Cells ◽  
Single Photons ◽  
Rod Photoreceptors ◽  
Neural Noise ◽  
Light Levels ◽  
Retinal Circuitry ◽  
Binary Event ◽  
Rod Bipolar Cells

At very low light levels the sensitivity of the visual system is determined by the efficiency with which single photons are captured, and the resulting signal transmitted from the rod photoreceptors through the retinal circuitry to the ganglion cells and on to the brain. Although the tiny electrical signals due to single photons have been observed in rod photoreceptors, little is known about how these signals are preserved during subsequent transmission to the optic nerve. We find that the synaptic currents elicited by single photons in mouse rod bipolar cells have a peak amplitude of 5–6 pA, and that about 20 rod photoreceptors converge upon each rod bipolar cell. The data indicates that the first synapse, between rod photoreceptors and rod bipolar cells, signals a binary event: the detection, or not, of a photon or photons in the connected rod photoreceptors. We present a simple model that demonstrates how a threshold nonlinearity during synaptic transfer allows transmission of the single photon signal, while rejecting the convergent neural noise from the 20 other rod photoreceptors feeding into this first synapse.

scholarly journals Quantum Structured Light: Non-classical Spin Texture of Twisted Single-photon Pulses

2021 ◽  
Author(s):  
Li-Ping Yang ◽  
Zubin Jacob
Keyword(s):  
Spin Density ◽  
Electromagnetic Waves ◽  
Single Photon ◽  
Structured Light ◽  
Three Dimensional ◽  
Quantum Spin ◽  
Single Photons ◽  
Spin Order ◽  
Spin Noise ◽  
Spin Texture

Abstract Classical structured light with controlled polarization and orbital angular momentum (OAM) of electromagnetic waves has varied applications in optical trapping, bio-sensing, optical communications and quantum simulations. The classical electromagnetic theory of such structured light beams and pulses have advanced significantly over the last two decades. However, a framework for the quantum density of spin and OAM for single-photons remains elusive. Here, we develop a theoretical framework and put forth the concept of quantum structured light for space-time wavepackets at the single-photon level. Our work marks a paradigm shift beyond scalar-field theory as well as the paraxial approximation and can be utilized to study the quantum properties of the spin and OAM of all classes of twisted quantum light pulses. We capture the uncertainty in full three-dimensional (3D) projections of vector spin demonstrating their quantum behavior beyond the conventional concept of classical polarization. Even in laser beams with high OAM along the propagation direction, we predict the existence of large OAM quantum fluctuations in the transverse plane which can be verified experimentally. We show that the spin density generates modulated helical texture beyond the paraxial limit and exhibits distinct statistics for Fock-state vs. coherent-state twisted pulses. We introduce the quantum correlator of photon spin density to characterize the nonlocal spin noise providing a rigorous parallel with fermionic spin noise operators. Our work paves the way for quantum spin-OAM physics in twisted single photon pulses and also opens explorations for new phases of light with long-range spin order.

scholarly journals Imaging Amyloid-β Deposits In Vivo

2002 ◽  
Vol 22 (9) ◽  
pp. 1035-1041 ◽  
Author(s):  
Brian J. Bacskai ◽  
William E. Klunk ◽  
Chester A. Mathis ◽  
Bradley T. Hyman
Keyword(s):  
Single Photon ◽  
Senile Plaques ◽  
Photon Emission ◽  
Multiphoton Microscopy ◽  
Amyloid Β ◽  
Neuronal Loss ◽  
High Sensitivity ◽  
Emission Computed Tomography ◽  
Tissue Samples

Alzheimer disease (AD) is an illness that can only be diagnosed with certainty with postmortem examination of brain tissue. Tissue samples from afflicted patients show neuronal loss, neurofibrillary tangles (NFTs), and amyloid-β plaques. An imaging technique that permitted in vivo detection of NFTs or amyloid-β plaques would be extremely valuable. For example, chronic imaging of senile plaques would provide a readout of the efficacy of experimental therapeutics aimed at removing these neuropathologic lesions. This review discusses the available techniques for imaging amyloid-β deposits in the intact brain, including magnetic resonance imaging, positron emission tomography, single photon emission computed tomography, and multiphoton microscopy. A variety of agents that target amyloid-β deposits specifically have been developed using one or several of these imaging modalities. The difficulty in developing these tools lies in the need for the agents to cross the blood-brain barrier while recognizing amyloid-β with high sensitivity and specificity. This review describes the progress in developing reagents suitable for in vivo imaging of senile plaques.

Cryogenic readout of superconducting nanowire single-photon detectors using high-sensitivity adiabatic quantum-flux-parametron circuits

2021 ◽  
Vol 34 (4) ◽  
pp. 044003
Author(s):  
Fumihiro China ◽  
Naoki Takeuchi ◽  
Shigehito Miki ◽  
Masahiro Yabuno ◽  
Shigeyuki Miyajima ◽  
...  
Keyword(s):  
Single Photon ◽  
High Sensitivity ◽  
Photon Detectors ◽  
Single Photon Detectors ◽  
Quantum Flux ◽  
Superconducting Nanowire

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 Photon-Detection-Probability Simulation Method for CMOS Single-Photon Avalanche Diodes

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 436 ◽  
Author(s):  
Chin-An Hsieh ◽  
Chia-Ming Tsai ◽  
Bing-Yue Tsui ◽  
Bo-Jen Hsiao ◽  
Sheng-Di Lin
Keyword(s):  
Detection Probability ◽  
Single Photon ◽  
Cmos Technology ◽  
Oxide Semiconductor ◽  
Cmos Process ◽  
Single Photons ◽  
Photon Detection ◽  
Important Indicator ◽  
Avalanche Diodes ◽  
Single Photon Avalanche Diodes

Single-photon avalanche diodes (SPADs) in complementary metal-oxide-semiconductor (CMOS) technology have excellent timing resolution and are capable to detect single photons. The most important indicator for its sensitivity, photon-detection probability (PDP), defines the probability of a successful detection for a single incident photon. To optimize PDP is a cost- and time-consuming task due to the complicated and expensive CMOS process. In this work, we have developed a simulation procedure to predict the PDP without any fitting parameter. With the given process parameters, our method combines the process, the electrical, and the optical simulations in commercially available software and the calculation of breakdown trigger probability. The simulation results have been compared with the experimental data conducted in an 800-nm CMOS technology and obtained a good consistence at the wavelength longer than 600 nm. The possible reasons for the disagreement at the short wavelength have been discussed. Our work provides an effective way to optimize the PDP of a SPAD prior to its fabrication.

scholarly journals Chaotic Quantum Key Distribution

Cryptography ◽  
2020 ◽  
Vol 4 (3) ◽  
pp. 24
Author(s):  
Noah Cowper ◽  
Harry Shaw ◽  
David Thayer
Keyword(s):  
Quantum Computing ◽  
Quantum Key Distribution ◽  
Single Photon ◽  
Photon Emission ◽  
Key Distribution ◽  
Maximum Amount ◽  
Single Photons ◽  
Single Photon Emission ◽  
Amount Of Information ◽  
Communication Scheme

The ability to send information securely is a vital aspect of today’s society, and with the developments in quantum computing, new ways to communicate have to be researched. We explored a novel application of quantum key distribution (QKD) and synchronized chaos which was utilized to mask a transmitted message. This communication scheme is not hampered by the ability to send single photons and consequently is not vulnerable to number splitting attacks like other QKD schemes that rely on single photon emission. This was shown by an eavesdropper gaining a maximum amount of information on the key during the first setup and listening to the key reconciliation to gain more information. We proved that there is a maximum amount of information an eavesdropper can gain during the communication, and this is insufficient to decode the message.

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