Saturday, September 14, 2013

Diatoms bring the quantum effect to life

Recent advances in the manipulation of molecules now allow us to also probe nanoporous silified biomaterials. We demonstrate the quantum coherent propagation of phthalocyanine through the skeleton of the algaAmphipleura pellucida. A micro-focused laser source prepares a molecular beam which is sufficiently delocalized to be coherently transmitted through the alga's frustule—in spite of the substantial dispersive interaction between each molecule and the nanomembrane.

Introduction and background. Physics associates all quantum matter with wave properties. Even almost 100 years after the introduction of this concept by Louis de Broglie, this phenomenon still simulates discussions among scientists and philosophers when it comes to matters of high complexity since it questions our common-sense understanding of reality or space–time. We usually don't perceive it since the de Broglie wavelength shrinks with the object's mass and velocity. Quantum interferometry therefore usually requires costly nanotechnology.

Main results. Here, we show for the first time that quantum coherence is sufficiently robust and biological grown nanostructures are sufficiently small and regular to allow the quantum coherent transport of individual dye molecules through the open pores of the silified skeleton of a marine alga suspended in vacuum. Amphipleura pellucida is part of the marine phytoplankton which you can collect on the beach. With a wall thickness of 90 nm and a surprisingly regular pore distance of about 200 nm it allows us to measure de Broglie wavelengths as small as a few billionths of a millimeter by quantum diffracting molecules at the biologically grown nanomask.

Wider implications. The Vienna experiment prepares macromolecular quantum interference for the first time with means that are in reach for almost every undergraduate physics lab. Moreover, Amphipleura pellucida is by no means a special case. Several tens of thousands of similar algae are waiting to be collected at the beach. Future studies of quantum diffraction are also expected to reveal information on the inner pore structure via phase tomography—complementary to the topography that is readily obtained in electron microscopy.