Dr. Abhishek Mandal, Ph.D.

Founder, Vision Science Academy, London, United Kingdom


Vision Science Academy Exclusive

The interaction between electromagnetic phenomena and visual processes is becoming widely debated in the domain of quantum mechanics. The latter is defined as a branch of physics which deals with the interplay between the basic building blocks of light i.e., photons, and matter i.e., atoms and subatomic particles. These electromagnetic particles fall on the retina and are readily detected by photoreceptors which convert these electromagnetic radiations into neuronal signals. This instance offers a unique insight into the nano-bio interface (Chakravarthi et al., 2008).

This article provides an overview of the biological phenomena which illustrate the mutual relationship between the fields of vision and quantum mechanics.

Photoreceptors in the Retina

The retinal photoreceptors include rods and cones where the former is specialised in the detection of dim light and the latter are responsible for detecting coloured aspects of visual fields. Three different types of cone cells are capable of detecting unique wavelengths of light, and their combined output constitutes our sense of colour vision in the brain.

The human retina has the ability to detect light signals comprising of single photons. The photoreceptors capture photons and convert these electromagnetic radiations into electrical and chemical signals. The outer segment of rod photoreceptors comprises of disc membranes which are loaded with the photosensitive pigment molecules known as rhodopsin. The rhodopsin molecule consists of a protein, opsin, which forms a bond with retinal, a molecular analogue of vitamin A.

In the resting state, 11-cis retinal binds with the opsin to constitute rhodopsin and hence, the neuronal cells of the retina remain depolarised. Upon the striking of photons, 11-cis retinal undergoes transformation into its counterpart i.e., all-trans retinal. This conversion initiates a cascade of chemical transformations in the rhodopsin molecule which culminates in the formation of metarhodopsin II. The latter triggers the activation of transducin molecules, which is implicated in hyperpolarisation and thereby, activation of the retinal neurons. This generates an electrical signal which is relayed to the brain’s visual area through the optic nerve (Sia et al., 2014).

Magnetoreception in Birds

Interestingly, light-sensitive chemicals have been localised within the photoreceptors found inside the birds’ eyes which are termed as cryptochromes. These chemicals absorb light and play a pivotal role in sensing directions through the detection of magnetic fields during migratory bird flights. This process is termed as magnetoreception (Mazzoccoli, 2022; Wiltschko & Wiltschko, 2019).

Photoreceptors and Circadian Rhythm

Photoreceptors play a crucial role in regulating the internal biological clock of an individual that controls a series of physiological processes, including sleep-wake cycles, endocrine functions, and thermoregulation. Photonic signals corresponding to blue wavelength are detected by a specialised group of ganglion cells located inside the retina. These cells contain a counterpart of rhodopsin called melanopsin which is only responsive to the blue wavelength of light. These retinal ganglion cells then project their output signals directly into the suprachiasmatic nucleus of the hypothalamus which constitutes the primary centre responsible for the regulation of sleep-wake cycle (Mazzoccoli, 2022).

Quantum properties in Vision

Quantum superposition and coherence are examples of quantum properties which are associated with visual processes. Quantum superposition refers to the simultaneous existence of different states of a quantum system while the phenomenon of quantum coherence also explores the relationship between different quantum phases. These properties have shown to increase the overall sensitivity of retinal vision at the molecular level (Khoshbin-e-Khoshnazar, 2014; Sia et al., 2014).

While the article highlights a few classical examples of the nano-bio interface, it is noteworthy that the exact significance of quantum effects in biological systems is currently a topic of ongoing research. Further detailed investigations are required to fully interpret the role of quantum mechanics in complex biological systems.



Chakravarthi, R., Rajagopal, A., & A R, U. D. (2008). Quantum Mechanical Basis of Vision.

Khoshbin-e-Khoshnazar, M. (2014). Quantum superposition in the retina: evidences and proposals. NeuroQuantology, 12(1).

Mazzoccoli, G. (2022). Chronobiology Meets Quantum Biology: A New Paradigm Overlooking the Horizon? [Review].       Frontiers in Physiology, 13. https://doi.org/10.3389/fphys.2022.892582

Sia, P. I., Luiten, A. N., Stace, T. M., Wood, J. P., & Casson, R. J. (2014). Quantum biology of the retina. Clinical & Experimental       Ophthalmology, 42(6), 582-589. https://doi.org/https://doi.org/10.1111/ceo.12373

Wiltschko, R., & Wiltschko, W. (2019). Magnetoreception in birds. Journal of the Royal Society Interface, 16(158), 20190295.