Quantum coherence and entanglement in the avian compass

Abstract

The radical pair mechanism is one of two distinct mechanisms used to explain the navigation of birds in geomagnetic fields. However, little research has been done to explore the role of quantum entanglement in this mechanism. In this paper, we study the lifetime of radical pair entanglement corresponding to the magnitude and direction of magnetic fields to show that the entanglement lasts long enough in birds to be used for navigation. We also demonstrate that, due to a lack of orientational sensitivity of the entanglement in the geomagnetic field, the birds are not able to orient themselves by the mechanism based directly on radical-pair entanglement. To explore the entanglement mechanism further, we propose a model in which the hyperfine interactions are replaced by local magnetic fields of similar strength. The entanglement of the radical pair in this model lasts longer and displays an angular sensitivity in weak magnetic fields, both of these factors are not present in the previous models.

The quantum needle of the avian magnetic compass

“…In support of this proposal, the photochemistry of isolated cryptochromes in vitro has been found to respond to applied magnetic fields in a manner that is quantitatively consistent with the radical pair mechanism (15). Aspects of the radical pair hypothesis have also been explored in a number of theoretical studies, the majority of which have concentrated on the magnitude of the anisotropic magnetic field effect (9,10,16,17,(19)(20)(21)(22)(23)(24)(25)(26)(27). Very little attention has been devoted to the matter we address here: the precision of the compass bearing available from a radical pair sensor (28).…”

“…A crucial element in all such calculations is the presence of nuclear spins whose hyperfine interactions are the source of the magnetic anisotropy (8,16). Most studies have focused on idealized spin systems comprising the two electron spins, one on each radical, augmented by one or two nuclear spins (9,(21)(22)(23)(24)(25)(26)(27)34). Only a handful has attempted to deal with realistic, multinuclear radical pairs (10,16,17,20).…”

“…Several studies have assumed, explicitly or implicitly, that the spin coherence persists for about a microsecond, i.e., the reciprocal of the electron Larmor frequency (1.4 MHz) in a 50-μT field (9,10,17,20). Either because the spin system was grossly oversimplified (9,(21)(22)(23)(24)(25)(26)(27)34), or because of this restriction on the spin coherence time, previous theoretical treatments have generally predicted the reaction yield to be a gently varying (often approximately sinusoidal) function of the orientation of the radical pair in the geomagnetic field. Although capable of delivering information on the direction of the field, such a compass would not provide a precise heading.…”

Quantum Unconscious Pre-Space: A Psychoanalytic/Neuroscientific Analysis of the Cognitive Science of Elio Conte–The Hard Problem of Consciousness, New Approaches and Directions

“…Quantum processes derive, and are sometimes isomorphically evidenced in macroreality (Tamulis et al, 2015, p.2;Cai et al, 2010;Pauls et al, 2013;Conte 2010;MarciakKozlowska and Kozlowski, 2015;Conte and Lucas, 2015). Isomorphisms, and/or self-similar structural dynamism across scales are evident.…”

Sensitivity and entanglement in the avian chemical compass

“…The hyperfine interaction has been modeled and simulated in order to understand how to optimize the sensitivity of the chemical compass [26]. Also, the role of quantum coherence and entanglement in the chemical compass has * kais@purdue.edu been discussed [27][28][29][30]. In addition, some research has been done using this theory to design devices to detect the external weak magnetic fields [23,[31][32][33].…”