Adopting quantum random walks in our classes ..

Could quantum mechanisms be driving some of the most elegant and inexplicable processes of life?
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PPT - Quantum random walks in energy landscapes …

The implementation of the walk is based on a loop architecture where the walker is realised by an attenuated laser pulse,. Its polarization, expressed in the horizontal and vertical basis states and , is used as the internal quantum coin and manipulated by standard linear elements, performing the coin operation. Different fibre lengths in the loop setup introduce a well defined time delay between the polarisation components, where different position states are uniquely represented by discrete time bins (mapping the position information into the time domain). To attain repeated action, we have completed the apparatus with a loop geometry that consists of the two paths A and B (see ), similarly to the 2d quantum walk. In contrast to previous experiments, here one full step of the PQW is executed by two round-trips in the loop architecture, alternating between paths A and B. Additionally to the standard half-wave plate (HWP) in path A (red area) we include a fast electro-optic modulator (EOM) in path B (green area), which now allows to actually change the underlying graph structure, and defines the additional graph operation. It is embedded between two partial shifts making up a full shift operation as thus implementing the unitary . The EOM is programmed to perform the transmission or reflection operation depending on whether a link is present or absent at the particular time encoded position in the configuration κ. Thus, changing the structure or size of the graph requires only a reprogramming of the timings delivered to the EOM. Detection at each step by a pair of avalanche photo diodes gives us access to the time evolution in the coin as well as in the position degree of freedom.

“We have shown that this quantum random-walk stuff really exists,” Fleming says.
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to involve high-level quantum effects is photosynthesis, ..

Starting from an apparently off-beat discovery of quantum coherence in low-temperature photosynthetic microbes in 2007, quantum coherence is emerging as a general principle of biological systems. The 2007 discovery of quantum coherence in microbes at low temperatures quickly extended to organisms at room temperatures and to multicellular plants. In this book, the authors extend the discussion to animal life, including quantum tunnelling in enzymes and the quantum entanglement based avian compass in European robins. It becomes apparent that rather then being an occasional oddity, quantum coherence has a general role in raising the efficiency of biological processing, and it may even allow for energy efficiency above the limit proposed by Carnot.

PowerPoint Slideshow about 'Quantum random walks in energy landscapes' ..
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Does that make sense? Of course not! Quantum mechanics is fundamentally strange and counterintuitive: Quantum particles don’t behave like soccer balls.

A quantum walk (QW) is the quantum mechanical analogue of a classical random walk ..
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for a quantum physical random walk

How is all these related to your question? Well, as I currently understand, researchers in the AMOPP(Atomic, Molecular, Optical and Positron Physics) Group in UCL are focussed on the quantum interaction of photosynthetic biomolecules with light to produce photosynthesis, even at room temperature. It turns out these kind of systems are described to some degree by such open quantum systems interacting with a Markovian environment as described above. I had also heard the claim that in these quantum processes the efficiency is as high as $95%$, so I thought it would be fun to introduce you to this area of research.

why plants can photosynthesize using that quantum random walk, ..

Recent quantum biology has thrown light on how life deals with molecular vibration or so-called noise. Molecular vibration or noise is seen to support rather than disrupt the quantum walk. Two types of molecular noise are used to support coherence; in the first place, there is low-level white noise spread across all frequencies, and derived from the jostling of all the molecules in a living cell. The second type of noise is more energetic, but limited to a small number of frequencies; this derives from the vibration of larger structures such as the chorophyll molecules along with their associated protein scaffolding. The bends and twists of the protein scaffolding are sources of vibration, particularly at certain frequencies. These more restricted vibrations have been indicated to correct quantum coherence when white or lower frequency noise threatened to produce decoherence. These two types of vibration are seen as driving quantum coherence within cells. Some research suggests that there is a ‘Goldilocks’ zone between aimless wandering of energy in a very cool environment, and retarded transport in a very hot environment, with the temperature inside photosynthetic organisms lying in the Goldilock’s zone.