Quantum Evidence 3

Summary and review of further papers related to material suggestive of quantum coherence in living matter

1.) Coherent spin transfers between molecularly bridged quantum dots - Ouyang M. & Awschalom, D. - Hameroff has suggested this as a method of sustaining coherence in microtubules. www.quantumconsciousness.org

2.) Memory depends on the cytoskeleton, but is it quantum? - Andreas Mershin & Dimitri Nanapoulos - Experiments demonstrating the involvement of microtubules in memory

3.) Evidence for coherent proton tunnelling in a hydrogen bond network - Horsewill et al

4.) New insights into enzyme catalysis - Scrutton et al

5.) Quantum afterlife: a way for quantum benefits to survive after entanglement ends - Based on Seth Lloyd

6.) Whole Brain - based on Raphael Gaillard - Evidence relative to consciousness and synchronistic activity in the brain

7.) Quantum entanglement in photosynthetic light harvesting complexes - Sarovar et al - Further evidence of quantum coherence and entanglement in biological systems.

8.) Coherence dynamics in photosynthesis: Protein protection of excitonic coherence - Lee, H. et al - Further evidence for quantum coherence in biological tissue

9.) Coherent intrachain energy migration in a conjugated polymer at room temperature - Elisabetta Collini & Gregory Scholes - Extension of the concept of protein protection developed by Engel et al.

1.)

Coherent spin transfers between molecularly bridged quantum dots

Ouyang M. & Awschalom, D.

Dept. of Physics and Center for Spintronics and Quantum Computing, University of California, Santa Barbara

Studies have demonstrated the instantaneous transfer of spin coherence through molecular bridges at a broad range of temperatures up to room temperatures. This work has been carried out in relation to quantum dots, where molecular bridges can act both as a physical link and as a channel for spin communication. Efficient transfer of spins can occur at room temperature. The authors propose a mechanism of π orbital spin transfer. The delocalised π orbital is suggested to provide a route for electrons to transfer through the molecules without losing energy or phase information and constituting coherent electron transfer. Data from studies shows that some molecules can serve as a medium for transferring quantum information.

The authors are interested in the application of spintronics to the construction of quantum computers, but Stuart Hameroff has referred to this paper in respect of the possible existence of quantum features relevant to both consciousness and quantum computing in biological tissue. The idea here is that π electrons can exist in hydrophobic pockets in proteins such as tubulin, and become quantum entangled where hydrophobic pockets are separated by less than 2nm. In a repetitive structures, such as the cytoskeleton, this could constitute a lattice geometry extending through the cell. This is speculated to constitute a large scale quantum process.

2.)

Memory depends on the cytoskeleton, but is it quantum?

Andreas Mershin and Dimitri Nanopoulos

In: Quantum Aspects of Life Eds. Derek Abbott, Paul Davies & Arun Pati

The paper starts by criticising Dennett, the philosopher who has dominated much of consciousness thinking in the last two decades, for trying to completely avoid the issue of non-trivial quantum involvement in living matter, rather than looking for experiments to test the predictions of this idea.

Experiments by the Mershin and Nanopoulos’s group (1. Mershin et al, 2004a) show that microtubules are important to memory storage and retrieval. It is stressed that these finding are consistent with, but not proof of, quantum mechanical involvement in these processes. The Mershin studies of drosophila (fruit flies) specifically show that there is a cytoskeletal pathway underlying associative olfactory memory encoding. This finding is assumed to also apply to other animals and to humans.

The authors argue that memory is a necessary ingredient of consciousness, and that if microtubules had been shown to have nothing to do with memory, microtubule related consciousness theories would have been falsified. I am not sure this is quite water tight, as presumably the raw experience of consciousness could access memory stores elsewhere in the brain. However, the involvement of microtubules in memory certainly extends their known functions, and makes it seem more probable that they are involved in consciousness.

It was a prediction listed by Stuart Hameroff that cytoskeletal networks would be found to be correlated with memory. In Mershin et al (2004a), the microtubule associated protein TAU was induced in drosophila. These altered drosophila, burdened with excessive TAU protein, showed a substantially lower memory score than normal drosophila after aversive conditioning. This leads to the conclusion that microtubules and microtubule associated proteins (MAPs) are involved in memory. The authors speculate that the ‘abacus like’ pattern of MAPs represent information coding, which is disrupted when extra MAPs are introduced.

The authors consider that their work shows that the cytoskeleton has a prominent role in information storage and manipulation. For further possible research the authors propose experiments that might test the ability of tubulin to support quantum coherence.

References:-

1.) Mershin, A et al (2004a) - Learning memory deficits upon TAU accumulation - Learning and Memory, 11, pp. 277-87

3.)

Evidence for coherent proton tunnelling in a hydrogen bond network

Horsewill et al

Science, 5 January 2001, vol. 291, no. 5501, pp. 100-103

The study observes coherent proton tunnelling in a network of four hydrogen bonds in a molecular calixarene. The study reports direct observation of coherent tunnelling with proton transfer amongst a network of four hydrogen bonds. Energy asymmettry must be small in order to minimise coupling with the environment, which could destroy quantum oscillations. Molecules with particular structures, such as that seen in calixarene, can minimise the environmental effects that might otherwise disrupt the oscillation of protons. Where wells have equivalent energy, the coupling to the environment is less strong, and it is expected that coherent tunnelling will persist. The calixarene molecule has energetically equivalent tautomers associated with possible proton positions. It is expected that the dynamics of one H bond will be influenced by the proton motion in an adjacent proton. This suggests a QM influence on processes that have normally been understood classically.

4.)

New insights into enzyme catalysis

Scrutton et al

European Journal of Biochemistry, (1999), 262, pp. 666-671

Quantum tunnelling may have a role in enzymatic H transfer. Tunnelling has been demonstrated for enzymes with C -H bonds. The probability of tunnelling is increased by the fluctuations of the protein scaffold, which reduces the distance that hydrogen must tunnel, and by the size of the proton. The H nucleus or proton is suggested to be often transfered in enzymes. H bonds have been shown to be responsible for the breakage of C -H bonds in enzyme molecules, and have also been shown to avoid thermodynamic disruption. H tunnelling in enzymes was only discovered in the 1990s, because the mass of the proton was previously thought to be inconsistent with tunnelling. Where C -H bonds are broken, this can drive H transfer by means of tunnelling. This study is again of interest in pointing out an area where quantum coherence is an active feature, despite the area having been previously thought to be wholly within the classical domain.

5.)

Quantum afterlife: a way for quantum benefits to survive after entanglement ends

Seth Lloyd

Scientific American, February 2009

Seth Lloyd of MIT has suggested that some of the effects of entanglement might continue to be felt even after entanlement has succumbed to decoherence. Lloyd has wondered if a sophisticated form of flash photography would be improved, if the outgoing photons of the flash were entangled. To his and others' surprise, the process worked best if all entanglement was destroyed during the experiment. It is not clear whether this enhancement was related to the previous entanglement or derived from other factors. Lloyd speculated that a few entangled photons might remain undetected and create enhancement. Testing for this effect would require an improvement in the sensitivity of existing instruments, but this might be available within the current year. If the effect is established, it is suggested that there might be implications for quantum computing and quantum cryptography.

Whilst this research has no direct relevance to quantum coherence in living matter, it does suggest that the issues of entanglement and decoherence may be more complex than has been suggested by those who has based there arguments on the rather simplistic approach of Tegmark (2000).

6.)

Whole Brain

New Scientist: 28 March 2009: Anil Ananthaswamy: based on Raphael Gaillard of INSERM

Raphael Gaillard of INSERM took the opportunity provided by the need to insert intercranial electrodes during medical treatments to test aspects of consciousness. The sample of electrodes across 10 volunteers covered most parts of the brain. Words were flashed in front of the volunteers, some of which they were conscious of, and some of which were masked so that there would only be unconscious processing. During the first 30 milliseconds there was not much difference between conscious and unconscious processing. After that time, there were several types of brain processing that only occurred where the subjects were conscious of the words concerned. The frequency and phase of neurons in different parts of the brain synchronised, and then in turn set of synchronised signals in other parts of the brain. For instance activity in the occipital lobes seemed to set off activity in the frontal lobes. The fact that this only occurred when subjects were aware of the words being shown, meant that this synchronisation was viewed by the researchers as a correlate of consciousness. The synchronisation of activity was spread over large parts of the brain leading the researchers to hypothesise that consciousness is spread over a large part of the brain rather than being concentrated in any one ‘seat of consciousness’.

The clear distinction here between conscious and non-conscious processing appears to contradict a core theme of Dennett to the effect that there is no such distinction between conscious and non-conscious activity. It also seems to argue against the once popular ‘electric plug’ theory of consciousness. This argued that consciousness was concentrated in and around the brain stem, because if anything seriously damaged the brain stem consciousness ceased. This research would rather seem to suggest that the brain stem is necessary but not sufficient for human consciousness.

The findings appear compatible with the idea that the widespread gamma synchrony is a correlate of consciousness. This view was made popular by, although not discovered by Crick and Koch in the 1990s, but fell from favour when it was discovered that the synchrony was with dendritic rather than axonal activity.

7.)

Quantum entanglement in photosynthetic light harvesting complexes

Mohan Sarovar, & K. Birgitta Whaley
Berkeley Center for Quantum Information and Computation and Dept. of Chemistry, University of California, Berkeley
&
Akihito Ishizaki & Graham Fleming
Dept. of Chemistry, University of California, Berkeley and Physical Bioscience Division, Berkeley, California

arXiv:0905.3787v1 [quant-ph] (2009)

This paper builds on the work of G. Engel and a number of other researchers in exploring quantum coherence and quantum entanglement in photosynthetic systems. The subject is crucial to the whole question of quantum consciousness, since when the chest beating and ridicule is stripped away, the most telling argument against quantum consciousness is that quantum features in the brain would be expected to decohere much too rapidly for them to be relevant to neural processes. Although these studies relate to photosynthetic systems, and most often to photosynthetic bacteria, rather than animal systems, they involve proteins that would be expected to suffer from similar decoherence trajectories to those of brain proteins.

A paper by J. Cai et al (1.) is quoted as showing that quantum entanglement can be generated and destroyed by non-equilibrium effects in noisy non-equilibrium environments. The authors of the present paper ask whether this means that entanglement can be observed in the non-equilibrium environment of living matter. They quote recent ultrafast spectroscopic studies including the G. Engel paper in Nature (2.) and those published in Science by Lee et al (3.) and Collini et al (4.). These studies all demonstrate quantum coherence in non-equilibrium systems, despite a decohering type environment.

Light harvesting complexes (LHCs) are densely packed molecular structures involved in the initial stages of photosynthesis. These complexes capture light, and the resulting excitation energy is transferred to reaction centres, where chemical reactions are initiated. LHCs are particularly efficient at transporting excitation energy in disordered environments. Simulations of the dynamics of particular LHCs predict that quantum entanglement will persist over observable timescales. Entanglement here would mean that there are non-local correlations between spatially separated molecules in the LHCs.

The molecules in the LHCs, referred to as chromophores, are close enough together for considerable dipole coupling leading to coherent interaction over observable timescales. The existence of coherence between molecules in these systems has been recognised for a decade or more (5. & 6.). This condition is seen as the basis for entanglement. Coherence in this area, known as the site basis, is necessary and sufficient for entanglement, and any coherence in the area will lead to entanglement, and can be viewed in experiments as a signature of entanglement.

The authors base part of their study on the description of the dynamics of a molecule in a protein in an LHC. This model indicates the coupling of some pairs of molecules due to proximity and favourable dipole orientation, thus effectively forming dimers. The wave function of the system is delocalised across these dimers.

There are also interactions between the molecules and the rest of the protein which involves decoherence effects. The speed with which this takes effect determines the timescale over which entanglement persists. The authors argue that the standard equation that has been applied in this case may not be valid. Two of the authors have developed an equation that is argued to take better account of the dynamics of chromophores in protein-chromophore complexes.

Using this equation, the interface of the LHC with light energy leads to a rapid increase in entanglement for a short time, followed by a decay punctuated by varying amounts of oscillation. The initial rapid increase reflects the coherent coupling of some parts of the LHC system. This entanglement decreases again as the excitation comes into contact with other parts of the protein. Some of the entanglement seen is not between immediately neighbouring molecules, but between more distant parts of the LHC. Entanglement in LHC is estimated to continue until the excitation reaches the reaction centre. The authors view this as a remarkable conclusion, since it shows that entanglement between several particles can persist in a non-equilibrium condition, despite being in a decoherent environment. The authors stress that the predictions made in these studies are verifiable by existing spectroscopy techniques.

Studies indicate that the observed rates and robustness of excitation energy transfer are a function of inter-site coherence. Entanglement is a by-product of the coherence, and it is not clear that in itself it has a significant role in light harvesting.

However, even if entanglement does not have a role in light harvesting, its existence may be significant for future technological developments. Light harvesting complexes are viewed as forming a possible basis for the design of man-made quantum devices, including quantum computers that would utilise entanglement.

From the point of view of consciousness studies, this and other papers concerned with quantum features in proteins involved in photosynthesis look to sound the death knell for the recent orthodoxy that quantum features could not persist in biological tissues, leaving the road open for the possibility of quantum coherence and entanglement in the brain.

References:-

1.) J. Cai et al (2008) - Dynamic entanglement in oscillating molecules - arXiv:0809.4906

2.) G. Engel et al (2007) - Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems - Nature, 446, 782

3.) H. Lee et al (2007) - Coherence dynamics in photosynthesis: protein protection of excitonic coherence - Science, 316, 1462

4.) E. Collini et al (2007) - Coherent intrachain energy migration in a conjugated polymer at room temperature - Science, 323, 369

5.) R. Monshouwer et al (1997) - Superradiance and exciton delocalisation in bacterial photosynthetic light harvesting systems – J. Phys. Chem. B, 101, 7241

6.) H. Van Amerongen et al (2000) - Photosynthetic excitons - World Scientific

8.)

Coherence dynamics in photosynthesis: Protein protection of excitonic coherence

Lee, H., Cheng, Y., Fleming, R.

Dept. of Chemistry, University of California Berkeley and Lawrence Berkeley National Laboratory

Science, 316, 1462 (2007)

Studies by the authors have demonstrated long-lasting coherence between excited states in photosynthetic bacteria. This can only be explained by strong correlations between chromophore molecules. The experimental results show that protein environments protect coherence in photosynthetic complexes, allow excitations to move coherently in space, and enable very efficient light energy harvesting in photosynthesis.

The solar energy harvesting found in photosynthesis relies on a first stage involving complex molecular machinery. Recent spectroscopy and theoretical modelling has started to show that electronic excitonic states may impact energy transfer in photosynthetic systems. G. Engel et al (1.) have demonstrated long-lived coherence between excitonic states, and energy transfer based on wavelike coherent motion in photosynthetic complexes. The authors designed experiments to study coherence between excited states, and these demonstrated that the protein environment protected coherence, and helped to optimise energy transfer in photosynthetic complexes.

One experiment looked at two chromophore molecules. The system provided near unity efficiency of energy transfer, and also demonstrates energy transfer between the chromophores. In the experiment, the exciton bands of the two chromophores became coherent. The experiment also shows that the time for dephasing of these molecules is substantially longer than would have been traditionally estimated. The traditional approach in particular ignored the coherence between donor and acceptor states. The longer time to dephasing of one as compared to the other of the experimental chromophores was taken to indicate a strong correlation of the energy fluctuations of the two molecules. This meant that the two molecules were embedded in the same protein environment. The authors argue that the traditional view that each molecule in a photosynthetic complex can be viewed independently cannot be sustained.

The adaptive benefit of long-lived coherence lies in the very efficient search for the electron donor. Thus the protein protection of coherence by means of correlated fluctuations produces the adaptive benefit of substantially enhanced energy transfer efficiency. The authors think it is too early to say that correlated fluctuations and consequent protection of electronic coherence is a general feature of photosynthetic complexes, but it is felt that the eventual description will certainly need to take account of coherence.

References:-

G.S. Engel et al - Nature, 446, 782 (2007)

9.)

Coherent intrachain energy migration in a conjugated polymer at room temperature

Elisabetta Collini and Gregory Scholes

Dept. of Chemistry/Instit. of Optical Sciences/Centre for Quantum Information and Control, University of Toronto

Science, 323, 369 (2009)

This is another in a series of recent studies indicating the existence of quantum coherence in proteins at high or even room temperature. In the context of the discussions on this site, this is mainly important in terms of undermining the principle argument against quantum consciousness, which is the expected rapid decoherence in brain proteins.

The authors conducted an experiment to observe quantum coherence dynamics in relation to electronic energy transfer. The experiment examined polymer samples with different chain conformations at room temperature, and recorded intrachain, but not interchain, coherent electronic energy transfer. It is pointed out that natural photosynthetic proteins and artificial polymers organise light absorbing molecules (chromophores) to channel photon energy. The excitation energy from the absorbed light can be shared quantum mechanically among the chromophores, depending on how the chromophores communicate.

Where this happens, electronic coupling predominates over the tendency towards quantum decoherence, (loss of coherence due to interaction with the environment), and what is described as a kind of standing wave connects donor and acceptor paths, and the evolution of the system is entangled in a single quantum state.

Within chains of polymers there can be conformational subunits 2 to 12 repeat units long, which are primary absorbing units or chromophores. Neighbouring chromophores along the backbone of a polymer have quite a strong electronic coupling, and electronic transfer between these is coherent at room temperature. These findings are consistent with observations of the protection of quantum coherence by Engel et al and Lee at al (1.&2.) that showed that fluctuation