Quantifying Magnetic Sensitivity of Radical Pair Based Compass by Quantum Fisher Information

Abstract

The radical pair (RP) based compass is considered as one of the principal models of avian magnetoreception. Different from the conventional approach where the sensitivity of RP based compass is described by the singlet yield, we introduce the quantum Fisher information (QFI), which represents the maximum information about the magnetic field’s direction extracted from the RP state, to quantify the sensitivity of RP based compass. The consistency between our results and experimental observations suggests that the QFI may serve as a measure to describe the sensitivity of RP based compass. Besides, within the framework of quantum metrology, we give two specific possible measurement schemes and find that the conventional singlet yield is corresponding to the measurement of total angular momentum. Moreover, we show that the measurement of fluctuation of the total magnetic moment is much more accurate than the singlet yield measurement, and is close to the optimal measurement scheme. Finally, the effects of entanglement and decoherence are also discussed in the spirit of our approach.

Navigating at night: fundamental limits on the sensitivity of radical pair magnetoreception under dim light

“…Use of the data processing inequality (Nielsen and Chuang, 2010; Beaudry and Renner, 2011) leads to a lower bound estimate of the precision with which a bird could orient itself using only the geomagnetic field as a directional cue (Section ‘Lower bound error in the head direction’). This approach avoids the difficulty faced by a simpler Fisher information treatment (Lehmann and Casella, 1998; Guo et al ., 2017; Vitalis and Kominis, 2017) which cannot account for arbitrary signal processing. We then estimate the photon flux into model cryptochrome-containing cells within the retina under the dim light conditions experienced by night-migratory songbirds (Section ‘Magnetoreceptor cells’) and assess the achievability of the information theory lower bound using a simple parameterised model of the singlet yield and two elementary data-processing approaches (Section ‘A model radical pair’).…”

Observations about utilitarian coherence in the avian compass

“…Additionally, the open quantum system nature of the system could be analysed in further detail 52,53 , employing numerically exact methods [54][55][56] for greater accuracy and to identify if non-Markovian dynamics [57][58][59] are of importance in realistic natural and artificial systems. Lastly, measures capturing nuclear and electronic subsystems 28,29 with clear links to compass operation should be developed to assist in the interpretation of experiments 60 , such as those utilising quantum control 61 , alongside protocols for their implementation 62 . Other resources [63][64][65][66] such as entanglement 67 may also/still be of interest for systems.…”

Hamiltonian simulation of quantum beats in radical pairs undergoing thermal relaxation on near-term quantum computers

“…4,5,[8][9][10][11][12][13][14] On the other hand, quantum theory has been applied to spin chemistry problems such as the magnetoreception phenomenon found in birds. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] In a recent study 1 we demonstrated thermal relaxation of radical pair systems undergoing the quantum beats phenomenon on a quantum computer. This work has inspired further quantum computing studies of more complex radical pair systems with nontrivial nuclear interactions, and the development of methods to simulate their full Hamiltonian.…”