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Frontiers in Physiology

Quantum Optics and Single Photon Transduction in Insect Eyes

David Wilby, Alberto Peruzzo, Natasha Mhatre, Graham Marshall, Rarity John, Jeremy L. O’Brien, Daniel Robert, Nicholas William Roberts, Ruth Oulton

Published Jan 1, 2013• 0 citations
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Abstract

Event Abstract Back to Event Quantum Optics and Single Photon Transduction in Insect Eyes David Wilby1, 2, 3*, Alberto Peruzzo2, Natasha Mhatre1, Graham D. Marshall2, John Rarity4, Jeremy L. O'Brien2, Daniel Robert1, Nicholas W. Roberts1* and Ruth Oulton2, 4 1 University of Bristol, School of Biological Sciences, United Kingdom 2 University of Bristol, School of Physics, United Kingdom 3 University of Bristol, Centre for Nanoscience and Quantum Information, United Kingdom 4 University of Bristol, Electrical and Electronic Engineering, United Kingdom Photon absorption is the primary event in vision. Whilst the sensitivity of an eye is governed by a number of factors, one of the most fundamental is the quantum efficiency of the photon absorption. Previous measurements have investigated whether insect retinal cells are capable of detecting single photons1. The results suggest a process of photon counting in the individual rhabdom and high quantum efficiencies (for example 60% in Locusta migratoria1). However the Poissonian distribution of photons means that single photons cannot be guaranteed, and therefore these earlier works have not allowed and deterministic verification of single photon transduction events. Modern day quantum photonics experiments widely use non-classical light sources, such as spontaneous parametric down-conversion (SPDC) heralded photon sources. This source produces a pair of photons, and therefore is guaranteed to deliver exactly one photon to a target whenever its twin ‘herald’ photon is detected2. Here we present measurements towards an experiment using a SPDC source to investigate single photon transduction in the locust (L. migratoria). We report characterising measurements of single photon transduction and detail the proposed application of a non-classical light source in visual neuroscience. This offers new possibilities in the characterisation and investigation of the first step in visual transduction in insect photoreceptors. Figure 1. The ‘quantum bump’ response to single photon absorption in the photoreceptor. Figure 1 References 1.P.G. Lillywhite, J. Comp. Physiol. 122, 189-200 (1977). 2. D.C. Burnham, D.L. Weinberg, Phys. Rev. Lett. 25, 84-87 (1970). Keywords: Transduction, Quantum Photonics, quantum efficiency, Locusta migratoria, single photon Conference: International Conference on Invertebrate Vision, Fjälkinge, Sweden, 1 Aug - 8 Aug, 2013. Presentation Type: Poster presentation preferred Topic: Transduction, signalling and coding Citation: Wilby D, Peruzzo A, Mhatre N, Marshall GD, Rarity J, O'Brien JL, Robert D, Roberts NW and Oulton R (2019). Quantum Optics and Single Photon Transduction in Insect Eyes. Front. Physiol. Conference Abstract: International Conference on Invertebrate Vision. doi: 10.3389/conf.fphys.2013.25.00061 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 28 Feb 2013; Published Online: 09 Dec 2019. * Correspondence: Mr. David Wilby, University of Bristol, School of Biological Sciences, Bristol, BS8 1UG, United Kingdom, drdavidwilby@gmail.com Dr. Nicholas W Roberts, University of Bristol, School of Biological Sciences, Bristol, BS8 1UG, United Kingdom, nicholas.roberts@bristol.ac.uk Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers David Wilby Alberto Peruzzo Natasha Mhatre Graham D Marshall John Rarity Jeremy L O'Brien Daniel Robert Nicholas W Roberts Ruth Oulton Google David Wilby Alberto Peruzzo Natasha Mhatre Graham D Marshall John Rarity Jeremy L O'Brien Daniel Robert Nicholas W Roberts Ruth Oulton Google Scholar David Wilby Alberto Peruzzo Natasha Mhatre Graham D Marshall John Rarity Jeremy L O'Brien Daniel Robert Nicholas W Roberts Ruth Oulton PubMed David Wilby Alberto Peruzzo Natasha Mhatre Graham D Marshall John Rarity Jeremy L O'Brien Daniel Robert Nicholas W Roberts Ruth Oulton Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

DOI
10.3389/conf.fphys.2013.25.00061

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Event Abstract Back to Event Quantum Optics and Single Photon Transduction in Insect Eyes David Wilby1, 2, 3*, Alberto Peruzzo2, Natasha Mhatre1, Graham D. Marshall2, John Rarity4, Jeremy L. O'Brien2, Daniel Robert1, Nicholas W. Roberts1* and Ruth Oulton2, 4 1 University of Bristol, School of Biological Sciences, United Kingdom 2 University of Bristol, School of Physics, United Kingdom 3 University of Bristol, Centre for Nanoscience and Quantum Information, United Kingdom 4 University of Bristol, Electrical and Electronic Engineering, United Kingdom Photon absorption is the primary event in vision. Whilst the sensitivity of an eye is governed by a number of factors, one of the most fundamental is the quantum efficiency of the photon absorption. Previous measurements have investigated whether insect retinal cells are capable of detecting single photons1. The results suggest a process of photon counting in the individual rhabdom and high quantum efficiencies (for example 60% in Locusta migratoria1). However the Poissonian distribution of photons means that single photons cannot be guaranteed, and therefore these earlier works have not allowed and deterministic verification of single photon transduction events. Modern day quantum photonics experiments widely use non-classical light sources, such as spontaneous parametric down-conversion (SPDC) heralded photon sources. This source produces a pair of photons, and therefore is guaranteed to deliver exactly one photon to a target whenever its twin ‘herald’ photon is detected2. Here we present measurements towards an experiment using a SPDC source to investigate single photon transduction in the locust (L. migratoria). We report characterising measurements of single photon transduction and detail the proposed application of a non-classical light source in visual neuroscience. This offers new possibilities in the characterisation and investigation of the first step in visual transduction in insect photoreceptors. Figure 1. The ‘quantum bump’ response to single photon absorption in the photoreceptor. Figure 1 References 1.P.G. Lillywhite, J. Comp. Physiol. 122, 189-200 (1977). 2. D.C. Burnham, D.L. Weinberg, Phys. Rev. Lett. 25, 84-87 (1970). Keywords: Transduction, Quantum Photonics, quantum efficiency, Locusta migratoria, single photon Conference: International Conference on Invertebrate Vision, Fjälkinge, Sweden, 1 Aug - 8 Aug, 2013. Presentation Type: Poster presentation preferred Topic: Transduction, signalling and coding Citation: Wilby D, Peruzzo A, Mhatre N, Marshall GD, Rarity J, O'Brien JL, Robert D, Roberts NW and Oulton R (2019). Quantum Optics and Single Photon Transduction in Insect Eyes. Front. Physiol. Conference Abstract: International Conference on Invertebrate Vision. doi: 10.3389/conf.fphys.2013.25.00061 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 28 Feb 2013; Published Online: 09 Dec 2019. * Correspondence: Mr. David Wilby, University of Bristol, School of Biological Sciences, Bristol, BS8 1UG, United Kingdom, drdavidwilby@gmail.com Dr. Nicholas W Roberts, University of Bristol, School of Biological Sciences, Bristol, BS8 1UG, United Kingdom, nicholas.roberts@bristol.ac.uk Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers David Wilby Alberto Peruzzo Natasha Mhatre Graham D Marshall John Rarity Jeremy L O'Brien Daniel Robert Nicholas W Roberts Ruth Oulton Google David Wilby Alberto Peruzzo Natasha Mhatre Graham D Marshall John Rarity Jeremy L O'Brien Daniel Robert Nicholas W Roberts Ruth Oulton Google Scholar David Wilby Alberto Peruzzo Natasha Mhatre Graham D Marshall John Rarity Jeremy L O'Brien Daniel Robert Nicholas W Roberts Ruth Oulton PubMed David Wilby Alberto Peruzzo Natasha Mhatre Graham D Marshall John Rarity Jeremy L O'Brien Daniel Robert Nicholas W Roberts Ruth Oulton Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.
The human eye contains millions of rod photoreceptor cells, and each one is a single-photon detector. Whether people can actually see a single photon|which requires the rod signal to propagate through the rest of the noisy visual system and be perceived in the brain|has been the subject of research for nearly 100 years. Early experiments hinted that people could see just a few photons, but classical light sources are poor tools for answering these questions. Single-photon sources have opened up a new area of vision research, providing the best evidence yet that humans can indeed see single photons, and could even be used to test quantum effects through the visual system. We discuss our program to study the lower limits of human vision with a heralded single-photon source based on spontaneous parametric downconversion, and present two proposed experiments to explore quantum effects through the visual system: testing the perception of superposition states, and using a human observer as a detector in a Bell test.
A study published in Nature Communications demonstrated for the first time that humans can consciously detect a single light particle by directing a single photon, controlled by quantum optical technology (SPDC), onto the cornea of human subjects. Breaking the conventional wisdom regarding the necessity of multiple photons for perception, the study showed that subjects directly perceived a single photon with a probability significantly above statistical chance. The study discovered a priming process where the probability of detecting a second single photon is significantly enhanced for several seconds after detecting an initial single photon, proving that the human visual neural network is a marvelous system capable of filtering information at the absolute quantum limit. [Quantum Biology Society] How fine a physical stimulus can human senses detect? In particular, whether our vision, through which we see the world, can perceive the most fundamental physical limit—a single particle of light (single photon)—has been a major subject of debate in the scientific community for over 70 years. While it was known that a single photoreceptor (rod cell) in the retina responds to individual photons , it was conventionally believed that to consciously perceive light, at least a few photons must arrive simultaneously to overcome noise. However, a phenomenal study has been published proving that the human eye and brain can break through this absolute quantum mechanical limit. The paper titled "Direct detection of a single photon by humans," published as an open-access article in the international journal Nature Communications, provides an answer to this fundamental question. A research team led by Professor Alipasha Vaziri and Jonathan N. Tinsley from the University of Vienna, the Research Institute of Molecular Pathology (IMP) in Austria, and The Rockefeller University in the USA, successfully spearheaded this groundbreaking experiment. ■ A Single Shot of Light Created with Quantum Optical Technology To overcome the limitations of conventional light sources, the research team utilized a quantum optical technology called spontaneous parametric down-conversion (SPDC). Through this, they built a perfectly controlled heralded single-photon source and performed over 30,000 rigorous psychophysics-based experimental trials, shooting this single photon into the corneas of subjects inside a pitch-black dark chamber. ■ The Human Brain Performs Quantum Noise Canceling The results were astounding. The subjects accurately identified when a single photon was emitted with a probability significantly above statistical chance. Even though only a minuscule amount of quantum energy struck the retina, the human visual system and neural networks in the brain filtered this absolute minimum unit of information out of macroscopic noise and visually perceived it. ■ A Light Seen Once is Seen Better: The Priming Effect of the Visual System Even more interestingly, the researchers discovered that the probability of detecting a second single photon was temporarily and significantly enhanced within a time window of a few seconds immediately after a subject detected an initial single photon. The researchers analyzed this as a priming process where the presence of an earlier photon temporarily enhances the effective gain of the visual system. This study proves that a living organism's sensory organs are not merely chemical sensors but sophisticated biophysical systems that interact directly with the quantum world, the smallest unit in the natural world. This discovery provides a new understanding of the signal processing mechanisms of brain neural networks and is expected to open the door to entirely new research exploring human vision and the brain using quantum states of light. https://www.nature.com/articles/ncomms12172
The rod photoreceptors in the retina are known to be sensitive to single photons, but it has long been debated whether these single-photon signals propagate through the rest of the visual system and lead to perception. Recently, single-photon sources developed in the field of quantum optics have enabled direct tests of single-photon vision that were not possible with classical light sources. Using a heralded source based on spontaneous parametric downconversion to generate single photons which were sent to an observer at either an early or late time, Tinsley and Molodtsov et al. (2016) had observers judge when the photon was seen. Based on the above-chance accuracy in both a subset of high-confidence trials and in all post-selected trials, they claimed to show that humans can see single photons. However, we argue that this work suffers from three major issues: self-contradicting results, inappropriate statistical analyses, and a critical lack of statistical power. As a result, we cannot conclude that humans can see single photons based on the data of this study. We present a careful examination of the statistical analyses and the internal consistency of the data, which indicated that none of the key evidence holds.
Over the last sixty years, classical information theory has revolutionized the understanding of the nature of information, and how it can be quantified and manipulated. Quantum information processing extends these lessons to quantum systems, where the properties of intrinsic uncertainty and entanglement fundamentally defy classical explanation. This growing field has many potential applications, including computing, cryptography, communication, and metrology. As inherently mobile quantum particles, photons are likely to play an important role in any mature large-scale quantum information processing system. However, the available methods for producing and detecting complex multi-photon states place practical limits on the feasibility of sophisticated optical quantum information processing experiments. In a typical quantum information protocol, a source first produces an interesting or useful quantum state (or set of states), perhaps involving superposition or entanglement. Then, some manipulations are performed on this state, perhaps involving quantum logic gates which further manipulate or entangle the intial state. Finally, the state must be detected, obtaining some desired measurement result, e.g., for secure communication or computationally efficient factoring. The work presented here concerns the first and last stages of this process as they relate to photons: sources and detectors. Our work on sources is based on the need for optimized non-classical states of light delivered at high rates, particularly of single photons in a pure quantum state. We seek to better understand the properties of spontaneous parameteric downconversion (SPDC) sources of photon pairs, and in doing so, produce such an optimized source. We report an SPDC source which produces pure heralded single photons with little or no spectral filtering, allowing a significant rate enhancement. Our work on detectors is based on the need to reliably measure single-photon states. We have focused on optimizing the detection efficiency of visible light photon counters (VLPCs), a single-photon detection technology that is also capable of resolving photon number states. We report a record-breaking quantum efficiency of 91 +/- 3% observed with our detection system. Both sources and detectors are independently interesting physical systems worthy of study, but together they promise to enable entire new classes and applications of information based on quantum mechanics.
We discuss our progress towards testing whether humans can see single photons, using a single-photon source based on spontaneous parametric downconversion and techniques from quantum optics. We review the existing evidence on single-photon vision, and show why no previous experiments with classical light sources (or otherwise) have truly been able to test it. We describe the heralded single-photon source we have built, which can be used for a definitive single-photon vision test, and discuss the statistical requirements and challenges of such a test. In pilot studies, we demonstrate that a two-alternative forced-choice design and our observer viewing station can measure the perception of very weak visual stimuli (including the weakest flashes of light ever directly tested, with just ~3 photons absorbed). We present two proposed experiments to test quantum effects through the visual system, which could contribute to our understanding of wavefunction collapse and the quantum-classical transition. We also discuss our work on other questions related to visual perception near threshold, including the length and completeness of temporal summation, which we have investigated in detail with a new experimental paradigm. We found that temporal summation continues for at least 650 ms when photons are delivered at a rate of about 30 in 100 ms, and that the completeness of summation may remain efficient over this window. Finally, we present some preliminary results on how 8- to 13-Hz alpha oscillations in the brain (which have complex effects on neural excitability and visual perception) might impact the detection of few-photon stimuli.
Over a century after the modern prediction of the existence of individual particles of light by Albert Einstein, a reliable source of this simple quantum state of one photon does not exist. While common light sources such as a light bulb, LED, or laser can produce a pulse of light with an average of one photon, there is (currently) no way of knowing the number of photons in that pulse without first absorbing (and thereby destroying) them. Spontaneous parametric down-conversion, a process in which one high-energy photon splits into two lower-energy photons, allows us to prepare a single-photon state by detecting one of the photons, which then heralds the existence of its twin. This process has been the workhorse of quantum optics, allowing demonstrations of a myriad of quantum processes and protocols, such as entanglement, cryptography, superdense coding, teleportation, and simple quantum computing demonstrations. All of these processes would benefit from better engineering of the underlying down-conversion process, but despite significant effort (both theoretical and experimental), optimization of this process is ongoing. The focus of this work is to optimize certain aspects of a down-conversion source, and then use this tool in novel experiments not otherwise feasible. Specifically, the goal is to optimize the heralding efficiency of the down-conversion photons, i.e., the probability that if one photon is detected, the other photon is also detected. This source is then applied to two experiments (a single-photon source, and a quantum cryptography implementation), and the detailed theory of an additional application (a source of Fock states and path-entangled states, called N00N states) is discussed, along with some other possible applications.