QUANTUM EFFECTS IN AVIAN MAGNETORECEPTION

Abstract

Quantum mechanics has made significant progress, transitioning from an abstract set of principles in physics to assuming crucial technological roles. This advancement has given rise to numerous research domains that rely on quantum mechanics as their theoretical bedrock. Examples include quantum computing, quantum communication, quantum cryptography, quantum meteorology, and more. Quantum biology represents one such area where quantum mechanics operates within a noisy biological environment on a scale with physiological consequences. The avian magnetoreception system is an example of a biological mechanism where quantum mechanics has observable physiological effects. Avian magnetoreception refers to the ability of migratory birds to sense the Earth’s magnetic field and utilize it for navigation. This mechanism is not yet fully understood and is one of the most important unresolved sensing problems in biology and spin chemistry. It relies on a chemical reaction that is sensitive to electron spin dynamics, involving a radical pair. The outcome of these reactions is influenced by the orientation of the Earth’s magnetic field and serves as a signal to the bird’s brain. Recent studies have demonstrated that electron transport in chiral molecules is spin-selective; therefore, it is known as chiral-induced spin selectivity (CISS). Interestingly, the chemical reaction involving the radical pair might occur within a chiral medium. Consequently, we explore the applicability of CISS within the framework of the radical pair mechanism of avian magnetoreception and investigate how it may impact the functionality of the avian compass. Our primary goal is to acquire a deeper understanding of the interplay between chiralityinduced spin selectivity (CISS) and various parameters within the radical pair model of the avian compass. We intend to assess the behavioral traits of the avian compass and contrast them with the outcomes of the CISS-enhanced avian compass. Characteristics such as compass sensitivity, functional window, susceptibility to radiofrequency disruption, and reaction yield, among others, are of particular significance in this context. Our plan is to investigate these characteristics in the context of a CISS-assisted avian compass and offer insights into their alignment with behavioral experiments. We further investigate the influence of CISS under different recombination rates of radicals. Furthermore, we explore how dipolar and exchange interactions, which typically hinder the functionality of the avian compass and reduce its sensitivity, come into play. Additionally, we examine the impact of decoherence on the system and demonstrate that CISS serves as a protective factor, preserving the compass’s sensitivity in the presence of decoherence. Our research has also delved into the impact of chirality-induced spin selectivity (CISS) on the coherence of avian magnetoreception. Additionally, we have conducted investigations into how decoherence and dipolar interactions influence the coherence of the CISS-assisted avian magnetoreception system. Finally, we establish a correlation between the chemical reaction yield and the system’s coherence. Furthermore, we aim to understand how CISS modulates this correlation. By studying avian magnetoreception, we realize that it operates as a spin-based quantum system even in noisy environmental conditions. Drawing cues from this observation, we have embarked on modeling semiconductor quantum dot-based spin qubits in a noisy environment. Since avian magnetoreception and QD-based spin qubits are spin-based systems, they share a common mathematical foundation. Therefore, as a secondary work, we have developed a simulation framework that enables the implementation of universal gate operations in a quantum dot-based system, considering the effects of decoherence due to various sources. The simulation framework has been applied to achieve several objectives: i) highfidelity universal gate operation, ii) quantum control to mitigate noise, and iii) randomness enhancement in quantum random number generators. The study’s objective in achieving high-fidelity universal gate operations is to determine how external parameters can be adjusted to minimize the impact of decoherence. Following this, a quantum control algorithm known as the gradient ascent algorithm is applied to create time-dependent external pulses, facilitating the achievement of precise gate operations with high fidelity. These two studies focused on achieving high-fidelity qubit operations. The last study focuses on applying the developed formalism for cryptographic applications. We use the developed formalism for high-fidelity qubit operation to propose a system that can function as a quantum random number generator. It leverages the inherent randomness of quantum measurements to produce random bits. These bits are then used to investigate corrector functions, which enhance the randomness of the generated bit sequence. This is particularly valuable in cryptographic applications where the level of randomness of generated bits is a crucial characteristic of cryptographic systems.