Synopsis: When is Biology Quantum?

A new formalism determines whether quantum-mechanical effects are necessary for photoactivated biological processes to occur.

The absorption of quanta of light (photons) is important for many biological processes such as vision, photosynthesis, and animal magnetoreception (birds, for instance, navigate by sensing how the Earth’s magnetic field steers electrons photogenerated in their retinas). Typically, photons are absorbed by some pigment-protein complex, triggering a sequence of chemical reactions that realize a biological function. Researchers have suggested that quantum effects play a role in these processes, but a quantitative assessment of their impact has proved problematic. Now, Atac Imamoglu at the Swiss Federal Institute of Technology (ETH) in Zurich and Birgitta Whaley at the University of California, Berkeley, have described these reactions as quantum measurements, in which the pigment-protein complex acts as a quantum meter measuring the incident light. They propose a new Hamiltonian model that can assess whether quantum coherence is an essential requirement for a given process.

Absorption of light generates quantum wave packets of excited electrons, leading to quantum correlations within the absorbing complex. Using a Hamiltonian formalism, the authors followed the evolution of the correlations to check whether the subsequent chemical products reflected the initial quantum coherence. They argue that quantum coherence can be considered as essential for the bioprocess only if it is maintained beyond the initial excitation of the complex. Analyzing photosynthesis, vision, and magnetoreception, they concluded that only the latter requires quantum coherence. For the other two, the ensuing chemical reactions may still occur without it, albeit with reduced efficiency. The new framework will provide testable predictions for experimentalists and guidelines for designing biomimetic sensing and energy transfer systems whose efficiencies are enhanced by quantum effects.

–Katherine Wright

This research is published in Physical Review E.


More Features »


More Announcements »

Subject Areas

Biological Physics

Previous Synopsis

Next Synopsis

Related Articles

Synopsis: Sound-Induced Bubbles for Drug Delivery

Synopsis: Sound-Induced Bubbles for Drug Delivery

Ultrasound-induced bubble formation, which may benefit drug delivery and other medical procedures, is affected by transitions in surrounding lipid membranes. Read More »

Synopsis: Fluid Dynamics Model for Cancer Patterns
Medical Physics

Synopsis: Fluid Dynamics Model for Cancer Patterns

Computer simulations indicate that friction and viscosity determine the patterns that cancerous cells form on skin tissue. Read More »

Synopsis: Sorting Blood Cells via Their Stiffness
Biological Physics

Synopsis: Sorting Blood Cells via Their Stiffness

A proposed modification to a microfluidic cell-sorting device could separate cells by their deformability, an important marker for several diseases. Read More »

More Articles