  We give a new explanation for why some biological systems can stay quantum
coherent for long times at room temperatures, one of the fundamental puzzles of
quantum biology. We show that systems with the right level of complexity
between chaos and regularity can increase their coherence time by orders of
magnitude. Systems near Critical Quantum Chaos or Metal-Insulator Transition
(MIT) can have long coherence times and coherent transport at the same time.
The new theory tested in a realistic light harvesting system model can
reproduce the scaling of critical fluctuations reported in recent experiments.
Scaling of return probability in the FMO light harvesting complex shows the
signs of universal return probability decay observed at critical MIT. The
results may open up new possibilities to design low loss energy and information
transport systems in this Poised Realm hovering reversibly between quantum
coherence and classicality.
