How can a biological system exploit quantum sensing to improve its ability to detect weak signals?

Quantum sensing utilizes quantum mechanical phenomena, such as superposition, entanglement, and coherence, to create sensors that can measure physical quantities with a sensitivity that surpasses classical limits. A biological system can exploit quantum sensing to improve its ability to detect weak signals by utilizing molecular systems that are highly sensitive to subtle changes in their environment. For example, consider a system that needs to detect weak magnetic fields. Instead of relying on classical magnetoreceptors, the system could utilize radical pairs whose spin dynamics are highly sensitive to magnetic fields. By monitoring the spin state of the radical pair, the system could detect extremely weak magnetic fields that would be undetectable by classical means. Another example involves sensing weak electric fields. A biological system could employ molecules that exhibit quantum superposition of electronic states, where the energy levels of these states are highly sensitive to electric fields. By measuring the energy level splitting, the system could detect weak electric fields with high precision. Quantum sensing can also be used to improve the detection of chemical signals. For example, a system could utilize entangled molecules, where the entanglement is sensitive to the presence of a specific chemical. By monitoring the entanglement, the system could detect even trace amounts of the chemical. One specific example is magnetoreception in birds, where cryptochromes are hypothesized to form radical pairs whose spin state is affected by the Earth's magnetic field, allowing birds to sense direction. By exploiting the quantum properties of these radical pairs, birds are able to detect extremely weak magnetic fields that would be imperceptible using classical sensors. Therefore, quantum sensing offers a powerful approach for biological systems to enhance their sensitivity to weak signals by exploiting quantum mechanical phenomena.