There are some meeting "lines"... Two examples involving the interaction of electromagnetic radiation with macromolecules: 1) photosynthetic events, and 2) "ab initio" prediction of biomacromolecular CD spectra. Another different example: elucidation of enzymatic events.

Wherever you like to better understand a conformation, a conformational transition, or some enzymaticall catalysed reaction. Also (macro-)molecular properties, possibly membrane dynamics, electron transport systems and things like this. I think the link to QM goes with the question for fundamental "laws" that finally determine the molecular constitution and interactions. For many biologically oriented questions it might be by far good enough to have "simple" models, like a channel being seen as just a kind of a "hole" letting some ions pass. However, there is a lot of QM involved when this is broken down to the inter-atomic interactions.

The understanding of the photosystems is quite much related to QM. Very obvious it this for the processes of photon absorption, Förster- and Dexter-transfer and all this.

Create arteficial chlorophyll

Maybe photoperception in plants through phytochrome would be a nice subject. Here are some others: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2839811/

Please kindly look at some related paper here:

thttp://tinyurl.com/l73k5vy

I claim to have pioniered the FIRST physiologic measurement - at the so-called "single-molecule level" - of the activation of any integrin receptor by any chemokine on any cell type on a living cell. This may still appear to be quite far away from real quantum physics, but the technique used, the atomic force microscope (AFM), which originated in the 1980s and is able (under very different conditions than the ones I developed for my pioniering approach 2001) can also measure subatomic phenomena. Who knows, if we - some day - can really look closer to what is really happening, when acitvating a single receptor like an integrin.

Unfortunately, my idea, project development, as well as my perfect results and collaborations were too good for German universities and the national academy members to let me develop my project myself... Others now get the millions of funding for "my" exclusive project.

Chapter Single-Molecule Studies of Integrins by AFM-Based Force Spec...

How do you come up with these awesome questions?

Thanks a lot for your very interesting and remarkable suggestions! I'm looking forward to further input...

One of the best application which brings these two subjects together is the study of bio-molecules like proteins using Atomic force microscopy.

I could also think on something "very crazy" in the mid- or long-range future (but based on the prinicples of radiotherapy, just with different beams getting through tissue (like light):

1) label some tissue, for example tumor tissue in a patient, more or less specifically with an non-toxic compound (like a tissue penetrating antibody or similar, and the non-toxic compound)

2) use some new source of beams, like laser light (or similar) to reach deep into the tissue (like radio beams) without damaging unlabeled cells or DNA

3) kill all cells of a tumor, metastasis, or whatever the target is.

Things like that may already be in use for superficial treatment of cells growing on a surface, skin, some inner organs.

Well, let’s start with something simple.

Living matter, while not eluding the ‘laws of physics’ as established up to date, is

likely to involve ‘other laws of physics’… It is, in my opinion, nothing else than the

principle of quantum theory over again.

Erwin Schrödinger, “What is life”

Bird’s navigation could be a simple example for a quantum system operating in biomolecular environment. It is based on interaction of a pair of entangled electron’s spin with the external magnetic field of Earth. This interaction can control a chemical interaction in a molecule (cytochrome) in the retina of a bird. As a result, the bird posess a visual perception of the Earth’s magnetic field lines. And is noteworthy, that the avian compass has much better temperature-tolerance, than the best man-made molecule used for entanglement, the C60 buckyball which encases a N atom.

The next issue could be a little bit more complicated.

I’m speaking about consciousness. This phenomenon is a great mystery, (one may fiind a lot of discussion about this here on RG) – because it is a highly complex*, chaotic* quantic process. (* the meaning of these words here are exceeding their every-day meaning)

Helas consciousness lies on the crossroads of physics and biology, and sometimes it is quite difficult for some authors to formulate a hypothesis which is in accordance with both the king and the queen of sciences. For instance, the theory put forward by the renamed physicist, Roger Penrose, where coherent microtubules should generate kind of teleportation-based consciousness, seems flawed. Because in a technological device a physicist knows, that the teleportation process (achievable for us today) has some probabilistic behaviour. More precisely, the receiver structure can end up through entanglement in exactly the same state as it is the sender – or (and this is more likely) in a state from which a simple (unitary) transformation will lead to that state. This information regarding the necessity of this transformation can not travel faster than light – and that is to save the theory of special relativity. But the flaw consist in my oppinion in the fact that while on a device of my lab I can command these unitary transformations, I can’t see the equivalent of these transformations in the unconscious neurobiological settlement. It seems to me, here a razor is needed. The Occamian.

OK, you may say, that the problem lies in my perception :)

There are various applications of quantum physics in biology. Example, you can treat the photosynthetic reaction centre as a quantum heat engine. Because of the quantum coherences, the efficiency, power and transport properties of the reaction centre can be increased beyond classical values. (http://phys.org/news/2013-02-day-noise-induced-quantum-coherence-photosynthetic.html, www.pnas.org/content/early/2013/01/30/1212666110‎, http://iopscience.iop.org/1742-6596/302/1/012037).

The interplay of coherence and decoherence has also shown to play a significant role in energy transfer processes in FMO complex, (http://pre.aps.org/pdf/PRE/v87/i6/e062712). Decoherece aslo affects brain processes (http://pre.aps.org/abstract/PRE/v61/i4/p4194_1)

Quantum physics is very much part of nature and also of biology. There are truly huge quantum objects out there. An impressive example is a neutron star, which has a typical mass of 2-4 x the one of our sun. Its shape and behaviour can only be explained in terms of quantum theory. A more mundane example is our humble simple atom. Without quantum mechanics the poor electron would just simply fall down and crash into the protons at its core. Similar effects keep molecules together or rule the transfer of charge within them. In this sense biology has a lot of quantum mechanics to it.

However, when we speak of quantum effects in quantum optics then we think of multiple particles that are at least in some sense independent and exhibit behaviour that cannot be explained in any other way. Many of the quantum effects described above are quantum in one sense or another, however, they are not more BIO than the hydrogen atom.

If in your question you allude to things LIVING then the answer is most certainly NO, because living things are complex and very complex systems cannot be quantum, because the very complexity they exhibit means that they couple easily to the environment and thus loose all quantum character almost immediately, i.e. no quantum superposition of two living things will last for any measurable time.

Wolf,

Of course, we are not discussing (for now) about superposition of two living systems. But superposition of quantic objects (excepting maybe the neutron-stars) is achieved inside of some living systems - even if they are very complex. And the superposition of electrons for instance can elicit some biological functions.

Certain migratory birds have the ability to sense very subtle variations in Earth's magnetic field. Superposition and entanglement are sustained in this living system for at least tens of microseconds, exceeding the durations achieved in the best comparable man-made molecular systems. This conclusion is starkly at variance with the view that life is too "warm and wet" for such quantum phenomena to endure. Complexity "per se" is not an insurmontable obstacle to realize entanglement.

http://arxiv.org/abs/0906.3725

Dear András,

I am not saying that quantum mechanics does not play an important role in biology. Quite on the contrary, it is the bases of any complex system. There is a severe problem with hype though. For something to take the label bio it should have some direct relation with it. Bio-molecules are only found in living nature -- DNA does not float around in space or is created spontaneously on the moon. The quantum-zeno effect in bird's eyes involves individual molecules in a thermal bath. There is nothing more quantum to it than in the hydrogen-bonds in the same molecule (and these bonds thankfully can live for a lifetime of a human).

Another problem with the claims of quantumness in biological systems is that it seems that the addition of the term "bio" reduces the burden of proof on the authors. There are huge conferences being organised around the question of how to protect entangled states from the environment and make them useful. Systems where this can be realised (and properly demonstrated) have to be cooled to a temperature of at least a few milli Kelvin above absolute zero, but more typically micro Kelvin. See for example

http://www.dwavesys.com/en/files/2011_04_29_d_wave_cryogenics_io_shielding.pdf

I am highly doubtful when someone claims to have found long living quantum-mechanical entanglement at temperatures 10000 times larger than that, especially if the prove is that his theory fits better to a single curve in a highly complex chemical environment. However, the future might prove them right. Only, right now this is way too large of a jump to take on a very very limited data set.

Dear Wolf

Yes, I have heard about the difficulties to maintain entanglement at great distances. Last time they've been around 130 km (teleportation between two islands in the Mediterranian maybe). Next step will be outer space (satellites, ISS, etc)

D-Wave made a fabulous contract with the CIA and NASA – but there are skeptics saying that their quantum computer is a bluff.

But Wolf,

these are artificial settlements, where the aim is to obtain teleportation through as many channels as possible (D-Wave) or as far as possible (ISS, etc).

I am talking about entanglement in a much more little scale. Can you measure the temperature inside a cryptochrome molecule? Actually in a pouch inside this molecule, limited and guarded by some heavy oxigen and chrome atoms? In such a confined space one can say that the temperature is 1 mK or maybe someone else can say that temperature has no meaning. There the quantum-phenomenon of entanglement can produce the biological process of magnetoperception (in bird's eye.)

However I agree with your observation regarding the experimental settlement. The article does not give details about the way how the experimenters established if the bird became disoriented. There are some references to some sort of supplimentary material...

First on the D-Wave computer. Just two days ago, I attended a lecture by a swiss professor (Matthias Troyer) who had the chance to test the latest d-wave computer. He found that indeed it works as a very specialised quantum computer. There might be no quantum speed up in the calculation, but it certainly uses quantum entanglement to do its calculation (but is still slower than a fast pc).

As to the bird's eye. Well even if the bird becomes completely disoriented by the RF there are many possible reasons why this might happen. A bird is not a controlled environment for this sort of experiments. My main point is just that this is a huge step up in complexity from experiments where they can measure and prove that they have entanglement. Science works in small steps, which each has to be proven. This is not the case here.

The other point is that we are still talking about molecules coupled individually to a thermal bath. There is nothing bio in this. The electron around the hydrogen atom in the bird's eye also requires quantum mechanics to keep it in its orbital. Does that mean that Bohr's orbitals are now bio as well?

It seems to me that we are are circling on the same orbital: you, with spin up and me – spin down.

I suppose the problem with D-wave is not related to the entanglement: since the Bell inequalities were established and the Aspect experiments accomplished, quantum-teleportation became a technical issue. To use it for arithmetics or other algorithms does not imply a qualitative upgrade compared to the experiments in Paris and later in Wien. They need a better (microK) refrigerator to use the D-Wave’s processor to solve the travelling salesman’s problem – but solving the problem in case of five cities does not opens the door which leads to the miracle of the parallell universes. Because scalability is a different question: beyond certain complexity-level emergent behaviour arise – and that applies for biologic and inanimate systems also (see the difference between elastic collision of two - or three balls). The problem of D-Wave is not related to entanglement (which it certainly uses) – but to scalability, which is not (yet) demonstrated and without this feature it will remain a bluff. But maybe the CIA has some additional informations, if they bought it.

As for the bird’s eye. I agree with your point related to the problems of interpreting the bird’s behaviour: the presence of entanglement was inferred from some (unprecised) movements of the bird in a cage. This article does not give details about the relations of the described theoretical model with the experimented phenomena. Which does not mean that the model is incorrect, but further analysis is needed.

Moreover, I agree with your next statement that science works in small steps.

But Wolf!

The problem is that Nature sometimes works in saults – and does not care two pins of what can we understand. Such a sault was represented by the appereance of RNA molecule on this planet. Later, another sault brought the DNA’s double helix (not in outer space or to the surface of the Moon, but here. We, humans, needed 200 millennia to understand this sault). Than came the revolution of the pluricellular organisms, than sex and so on. What a wonderful world – as Armstrong sung – all consequence of these saults. One of the main purpose of science is to create the models which could explain these saults. But human intellect has a problem in realizing similar saults – and that is why science works in small steps. The atomic theory of Democritos could be regarded today as a very small step for (a?) man - in a wrong direction. But in it’s time it was a giant leap for mankind. And similar stories are abundant in the history of science. That is why I agree with the lines of Shakespeare:

There are more things in heaven and earth, Horatio,

Than are dreamt of in your philosophy.

Because such a sault could be present in the eyes of a humble robin. This biological system – as the whole wonderful world around us – is constructed ultimately by the atoms and molecules which are governed by the laws of quantum mechanics. Chemistry, physics, biology and cosmology are all emergent features of quantum mechanics. So, ultimately, you are right of beeing upset if we are talking about QM in biology: QM is ubiquitous!

My point is here that in the case of the avian compass we have to deal with a sault of Nature: magnetoperception in bird’s eye is an exceptional feature where a very subtle QM-al relation is involved to obtain a biological function. But as you stated, science works slowly and we need time to understand this...

Dear András,

I like your positive attitude. You are right sometimes things work in huge leaps. It is just that the evidence is very thin to prove that the thing uses the mechanism that they are claiming, and even if it does it is just not more quantum than the hydrogen atom. There is no entanglement over a distance (and it is not even claimed) and nothing bio other than a large molecule (and they have done a huge amount of quantum work (including real quantum calculations) in NMR of large molecules.

But you are right, we are a bit spinning around each other's opinions. I like clean clear concepts without too much up-labeling and you are the optimist. I salut that.

All right then, spin-partner!

You'll keep an eye on the claims of entanglement in case of the avian compass and I will scout if the CIA's alien or time-traveller councellors were right in the case of D-Wave.

“Who can say where the road goes

Where the day flows: only time “

(Enya)

But let's give a spin to the question (if Helmuth doesn't mind).

As much as I know the experiments with quantum entanglement and the associated quantum teleportation are all man-made, artificial phenomena. The novelty of the avian compass would be the fact that it uses a kind of “natural” entanglement (time will tell if this statement based on the article which is linked above is true. You have planted the seed of doubt and I salute that).

The spin to Helmuth's question would be: Can anyone think of an (other) application of quantum entanglement occurred naturally in living systems? Helas I don't have the necessary subscriptions to examine Himangshu's links. From the last link an abstract came up, where Max Tegmark spoke against Penrose's concept that the brain would act as a quantum computer and consciousness would be related to quantum coherence. Well, I agree with Tegmark that the microtubules can not act as a carrier for entangled particles. But in my opinion this standpoint does not mean that quantum coherence should be excluded from the list of phenomena which are contributing to the appearance of consciousness. It means that we have to examine other situations where natural entanglement occurs. In bio and non-bio circumstances alike.

And we should examine also the reverse of this spinned question: could be bird's magnetoperception explained by other neurobiological mechanisms (without entanglement?)

I hope I'm not over simplifying this but...It seems to me that there are plethora of examples of quantum physics meeting molecular biology. So, in no particular order:

- Fluorescent protein from jellyfish. Isn't the quantum yield and efficiency of the protein directly related to it's molecular structure?

- Fireflies produce chemicals that are bio luminescent.

- The Catch-Bond. The bond strength and lifetimes of certain cell surface protein change as a function of sheer stress. AND the organelles of the cells contribute to this 'shear enhanced adhesion.'

How about the techniques that use the principles of quantum physics to study molecular biology?

- Atomic Force Microscopy. (AFM) AFM can be used to investigate single molecular bond interactions.

- Optical Tweezers - Light can be used to trap nano-particles or even macromolecules like protein.

Am I on the right track here?