Approaching the quantum limit of energy resolution in animal magnetoreception

TL;DR

This paper investigates how close biological magnetoreception mechanisms come to the fundamental quantum energy resolution limit, providing insights into quantum biology and guiding the development of advanced biomimetic sensors.

Contribution

It quantitatively assesses the proximity of animal magnetoreception mechanisms to the quantum energy resolution limit, linking biological sensing to fundamental quantum constraints.

Findings

Magnetoreception mechanisms approach the quantum energy limit

The energy resolution informs model-independent biological sensing analysis

Insights into quantum biology and sensor design are gained

Abstract

A large number of magnetic sensors, like superconducting quantum interference devices, optical pumping and nitrogen vacancy magnetometers, were shown to satisfy the energy resolution limit. This limit states that the magnetic sensitivity of the sensor, when translated into a product of energy with time, is bounded below by Planck's constant, hbar. This bound implies a fundamental limitation as to what can be achieved in magnetic sensing. Here we explore biological magnetometers, in particular three magnetoreception mechanisms thought to underly animals' geomagnetic field sensing: the radical-pair, the magnetite and the MagR mechanism. We address the question of how close these mechanisms approach the energy resolution limit. At the quantitative level, the utility of the energy resolution limit is that it informs the workings of magnetic sensing in model-independent ways, and thus can provide subtle consistency checks for theoretical models and estimated or measured parameter values, particularly needed in complex biological systems. At the qualitative level, the closer the energy resolution is to hbar, the more "quantum" is the sensor. This offers an alternative route towards understanding the quantum biology of magnetoreception. It also quantifies the room for improvement, illuminating what Nature has achieved, and stimulating the engineering of biomimetic sensors exceeding Nature's magnetic sensing performance.