Basis-independent system-environment coherence is necessary to detect magnetic field direction in an avian-inspired quantum magnetic sensor

Abstract

Advancing our understanding of non-trivial quantum effects in biomolecular complexes operating in physiological conditions requires the precise characterisation of the non-classicalities that may be present in such systems as well as asserting whether such features are required for robust function.Here we consider an avian-inspired quantum magnetic sensor composed of two radicals with a third "scavenger" radical under the influence of a collisional environment that allows to capture a variety of decoherence processes. We show that basis-independent coherence, in which the initial systemenvironment state is non-maximally mixed, is necessary for optimal performance of the quantum magnetic sensor, and appears to be sufficient in particular situations. We discuss how such nonmaximally mixed initial states may be common for a variety of biomolecular scenarios. Our results therefore suggest that a small degree of coherence-regardless of basis-is likely to be a quantum resource for biomolecular systems operating at the interface between the quantum and classical domains.

Quantum collision models: Open system dynamics from repeated interactions

“…[213] investigated quantum transport across a Fenna-Matthews-Olson complex, while Ref. [214] studied decoherence of an avian-inspired quantum magnetic sensor. Other recent applications include: simulating the Unruh effect [215], quantum friction [216] and information scrambling [217].…”

“…Section 4.4) with associated collision map E m . As shown by (214), each Λ mn alone describes a fully Markovian collisional dynamics [cf. Eq.…”

Observations about utilitarian coherence in the avian compass

“…The radical-pair compass, by its design, relies on the coherent interconversion of singlet and triplet electronic states and, thus, the presence of a certain degree of singlet-triplet coherence is essential 14,16,31 . However, we find that the amount of electronic coherence does not generally correlate with increased compass performance across differently oriented systems.…”

“…(40). The relative entropy of ρ with respect to the maximally mixed state, S ρ|| 1/d = log d − S [ρ], has likewise been employed to quantify the amount of basis-independent coherence 31 .…”

“…(30) with comparable conclusions. Le and Olaya-Castro have recently investigated a threespin system subject to collisional, symmetry-breaking environmental interactions 31 . The authors demonstrate that magnetosensitivity in this system requires coherence and suggest that a small degree of coherence, regardless of basis, is likely a quantum resource for biomolecular systems.…”