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QTBS2009 Titles and Abstracts

Session:           12 January, Monday

Speaker:

Artur Ekert

Title:

30 min of quantum exposure

Abstract:

The essence of quantum theory explained with one simple example, few anecdotes and no jokes

Speaker:

Juan Pablo Paz

Title:

Decoherence and the transition from quantum to classical

Abstract:

I present a brief overview of the process of decoherence and its relevance in the context of the quentum-classical transition. Using quantum Brownian motion as a toy model I analyze some of the generic features of decoherence. I discuss the nature of correlations that are established between the system and the environment in the course of decoherence

Speaker:

Nathan Babcock

Title:

Living Quantum Engines

Abstract:

I provide my vision of the theoretical foundation necessary to build practical thermodynamic machines on the quantum scale. I briefly compare Equilibrium Statistical Mechanics with Thermodynamics, sketching out the inability of the former to provide a rigorous theoretical foundation for the latter. I introduce ideas from the emerging field of Quantum Thermodynamics, a promising candidate for a rigorous Foundation of Thermodynamics. Finally, I describe my research on quantum effects in the engine of life: the cellular respiratory chain.

Speaker:

Tony Leggett

Title:

Quantum effects in biology:how severe are the constraints imposed by decoherence considerations?

Abstract:

It is widely agreed that if biological systems are to exploit quantum-mechanical principles in any sophisticated way,it is necessary that they avoid or minimize the effects of "decoherence".However,in the literature the concept of decoherence is often ambiguous.I give a careful definition of the phenomenon and a generic model for its discussion,and review some standard ways in which it can be avoided (decoherence-free subspaces,spin echoes,Zeno effect,adiabaticity...).I discuss briefly whether biological systems are likely to take advantage of any or all of these prescriptions.

Speaker:

Philip Walther

Title:

All-optical Quantum Computation

Abstract:

Photons have an intrinsic lack of decoherence and are simple to control by standard off-the-shelf components. Therefore optical qubits are playing an important role in investigating foundations of quantum information processing.

Furthermore, photonic qubits for quantum computation are particularly attractive because they could interface to various quantum communication applications. In recent years, one-way quantum computing has become an exciting alternative to existing proposals for quantum computers. In this specific model, coherent quantum information processing is accomplished via a sequence of single-qubit measurements applied to an entangled resource known as cluster state.

Speaker:

Frances Wang

Title:

Are there quantum effects in human perception and judgments?"

Abstract:

Recently several effects in human perception and judgments have been proposed as examples of quantum information processing.  For example, human perception is shown to be a discrete process instead of a continuous one;  the dynamics of the perception of bistable ambiguous figures and binocular rivalry resembles a quantum Zeno effect; human decision making appears to have an interference effect, which is paradoxical in the classical probability theory, but is perfectly compatible with quantum probability. I will discuss related empirical findings and their theoretical interpretations.

Speaker:

Paul Davies

Title:

Can the known laws of physics successfully describe biological systems?

Abstract:

To a physicist, the living state of matter seems so extraordinary as to be almost miraculous. The founders of quantum mechanics believed they were on the verge of explaining life's bizarre and unique properties, although they conceded that it may require a "post-quantum mechanics" to do so. Decades later, their dream remains unrealized. What would it mean for there to be "biological laws," quantum or otherwise, and how would they integrate with the known laws of physics? If life were to harness quantum effects, how would those effects be manifested? I shall discuss some circumstantial evidence that some biological processes operate at "the quantum edge," and speculate about the possible role of quantum replicators in the origin of life.

Session:           13 January, Tuesday

Speaker:

Janet Anders

Title:

Coupled systems and their correlation properties

Abstract:

Speaker:

Valerio Scarani

Title:

Quanta in a black box

Abstract:

In general, a statement about the non-classicality (or "quantumness") of a physical system requires a detailed description of the system itself. For instance, only a person familiar with the classical theory of the electromagnetic field can realize that the black-body radiation requires a departure from classical physics.

In some instances, however, non-classicality can be assessed in a fully black-box scenario, in which the system under study and the measurements that are performed are completely uncharacterized. Specifically, this is the case when Bell-type inequalities are violated without signaling.

This talk presents the meaningful notions to the topic, along with some of the achievements of the black-box approach in the context of quantum information tasks.

Speaker:

Nicolas Gisin

Title:

Abstract:

Speaker:

Libby Heaney

Title:

Condensation effects in biological systems

Abstract:

The seminal papers of Froehlich [1], predicting that biological systems may support the coherent quantum effect of Bose-Einstein condensation, will provide the motivation for this talk. We begin by reviewing the phenomena of Bose-Einstein condensation from the viewpoint of cold atoms. This will form the basis of explaining how condensation could occur in a biological system equipped with a long-range interaction between a set of oscillating dipoles.  In order to convince the listener that non-trivial quantum effects could survive in the warm environment of a biological system, I will draw parallels between the Froehlich model and coherent non-equilibrium phenomena in concrete quantum many-body systems, such as spin gases, spin chains and semi-conductor micro-cavities.  One may also wonder what useful purpose a spatially coherent state would serve a biological system, if it were found to exist.  The final part of this talk will illustrate that spatial coherence of a Bose-Einstein condensate is intimately related to entanglement and, moreover, that this entanglement is useful for quantum information processing.

[1] H. Froehlich, Int. J. Quant. Chem. 2 641 (1968), H. Froehlich, ibid 23 1589 (1983), H. Froehlich, Phys.Lett. 26A 402 (1968).

Presentation: PowerPoint File (3.1MB)  

Speaker:

Richard Cogdell

Title:

The Structure and Function of Purple Bacterial Antenna Complexes; from single

Abstract:

A typical purple photosynthetic bacterium contains two types of light-harvesting complexes, called LH2 and the reaction centre/LH1 core complex. This presentation will describe their three dimensional structures as determined by x-ray crystallography. Then it will show how their absorption spectra can be accounted for using a combination of this structural information and using data obtained from single molecule spectroscopy (a collaboration with Juergen Koller from Bayreuth). Finally how these complexes are organised in native photosynthetic membranes will be descibed.

Speaker:

Graham Fleming

Title:

Photosynthetic Light Harvesting and Quantum Dynamics:

Abstract:

The newly developed spectroscopic technique of two-dimensional electronic spectroscopy is directly sensitive to the phase evolution of quantum coherences. Application of this method to photosynthetic pigment-protein light harvesting complexes has revealed long-lasting electronic quantum coherence in these systems raising the question of whether photosynthetic complexes perform quantum searches analogous to, for example, Grover’s algorithm, to locate their target state. In this talk I will briefly summarize the evidence for long-lived quantum coherence in photosynthesis, and describe an experiment that shows that the protein may act to protect coherence in these systems. I will briefly discuss work of others introducing ideas of quantum random walks and discuss shortcomings in current theoretical approaches. I will conclude by describing a new quantum master equation approach which incorporates realistic phonon relaxation dynamics. This reduced hierarchy approach correctly interpolates between weak and strong coupling limits (photosynthetic systems have intermediate strength coupling), and predicts much longer coherence decay times than standard approaches such as (full) Redfield theory.

  

Presentation: PDF File (11MB)


Session:      14 January, Wednesday

Speaker:

Bruno Sanguinetti

Title:

How Much is Life? Approaches to finding a useful measure of vitality

Abstract:

What is life? This is a question that many brilliant minds have asked and have been able to answer only in part. Most of us would agree that a person is alive and a stone is not. In many other cases however the distinction is more a matter of opinion than fact: are viruses, computers, embryos alive? Are swarms, ant colonies, companies and networks life forms? The question "what is life?" is difficult. A good definition will – no doubt – be a slow, collaborative process that might take generations. In the meantime there are some questions such as "what is the role of quantum mechanics in life" or "did quantum mechanics play a role in the arising of life?" that would benefit from a working definition, as simplistic as it might be. In this talk I will describe an approach to measuring the "vitality" of a system in a way that is useful to answering simple questions formally. This work being in its infancy, ample time will be left for discussion and insights from the audience.

Presentation: PDF File (4MB)

Speaker:

Wolfgang Wiltschko

Title:

The Magnetic Compass of Birds

Abstract:

The geomagnetic field of the earth represents a reliable, omnipresent source for directional information for birds and other animals. The avian magnetic compass was analyzed in three not closely related birds species using different behaviors, namely migratory orientation in European Robins, Erithacus rubecula, homing in carrier pigeons, Columba livia f. domestica and directional training in young domestic chickens, Gallus gallus.

In all three species, the magnetic compass showed the following characteristic properties:

(1) it proved to be an 'inclination compass', not based on the polarity of the magnetic field, but on the (axial) course of the field lines and their inclination in space, thus discriminating between 'poleward' and 'equatorward' instead of between magnetic North and South.

(2) It works only in a narrow functional window around the intensity of the ambient magnetic field, with slightly stronger or weaker fields leading to disorientation.

(3) It is strongly lateralized, with reception taking place in the right eye and the information processed in the left hemisphere of the brain.The present model by Ritz et al. (2000) assumes radical pair processes in specialized photo¬pigments as the physical basis underlying magnetoreception, with cryptochromes suggested as possible receptor molecule.

This is supported by the following experimental findings:

(1) Magnetic compass orientation is light dependent, requiring light from the short wavelength part of the spectrum

(2) It can be disturbed by oscillating fields in the MHz range, when these fields are presented in an angle to the vector of the geomagnetic field

(3) Cryptochrome is present in the retina birds.By using migratory orientation as a criterion whether of not magnetoreception was unhindered, we did 'behavioral spectroscopy', exposing robins to oscillating fields of different frequencies and intensities. With this method, we could estimate the lifetime of the crucial radical pair to lie between 2 and 10 ms and demonstrate that the receptive processes have a very sensitive resonance at the Larmor frequency of the electron.

 

Presentation: PowerPoint File (9.4MB)  

Speaker:

Thorsten Ritz

Title:

Abstract:

Presentation: PowerPoint File (7.2MB)

Speaker:

Kiminori Maeda

Title:

Quantum Spin dynamics observed in the chemical reaction

Abstract:

Radical pair (RP) reaction is one of the most basic chemical reactions in chemistry and biology.  Since the following chemical process of the radical pair is electron spin selective, the quantum mechanical spin dynamics directly appears in the chemical reaction. In the present talk, the way to manipulate the electron spin dynamics by external magnetic field and its effects are demonstrated in the photochemical electron transfer reactions of a carotenoid-porphyrin-fullerene molecular triad[1] and biomolecular systems.

1. The effect of the pulsed electron spin resonance. Magnetic resonance can freely change the direction of electron spin polarization. Therefore the electron spins of RP can be manipulated by this and its effect can be observed in a chemical reaction process.  In the present talk, we demonstrates the radical pair dynamics studied by the reaction yield detected pulsed magnetic resonance (pulsed RYDMR) techniques. [2-3]

2. Extremely weak magnetic field effect and a chemical compass. Recently, the radical pair mechanism (RPM) has become considered as one of the important mechanisms for the animal navigations contrasting with the mechanism involving magnetite particles.[5]  Since Ritz et al. proposed a radical pair mechanism in retina of a bird’s eye as a mechanism for the bird navigation,[6-7] attention on the magnetic field effect (MFE) on the radical pair dynamics in very weak magnetic field has increased.

In the present talk, we demonstrate clear experimental observations of the effect of near earth magnetic field (~40 ï­T) on the radical pair dynamics and the anisotropic behavior of the magnetic field effect[4].  For the observation of the anisotropic MFE, we have used the photoselection technique of the probe beam for measurement of transient absorption signal. The observed anisotropic pattern was validated by the reference of the results in another direction of the probe beam.

3. Magnetic field effect in Escherichia Coli DNA Photolyase.[8] Besides the fact that DNA Photolyase has a function of DNA repair, the photolyase is one of the most interesting model systems because it has very similar structure with Cryptochrome (CRY), which has been identified as strong candidates of the photochemical compass for animal navigations[6-7].  In the E.Coli DNA Photolyase, we have successfully observed formation of the long lived radical pair through the sequential electron transfer reactions by transient absorption technique and clarified the existence of the significant MFE that is attributed to radical pair mechanism (RPM).

References:

[1] G.Kodis, P.A.Liddel, A.L.Moore, T.A.Moore, D. Gust, J. Phys. Org. Chem. 17, 724(2004).

[2] S.A.Dzuba, I.I.Proskuryakov, R.J. Hulsebosch, M.K.Bosch, P.Gast, A.J.Hoff, Chem. Phys. Lett. 253, 361(1996).

[3] V.R.Gorelik, K.Maeda, H.Yashiro, H.Murai, J. Phys. Chem. A 105, 8011(2001).

[4] K.Maeda, K.B.Henbest, F.Cintolesi, I.Kuprov, C.T.Rodgers, P.A.Liddell, D.Gust,

Speaker:

Chris Rodgers

Title:

Effects of spin on chemical reactions

Abstract:

Chemical reactions that involve radical intermediates can be influenced by magnetic fields, which act to alter their rate, yield, or product distribution. These effects have been studied extensively in liquids, solids, and constrained media such as micelles. They may be interpreted using the radical pair mechanism (RPM). Such effects are central to the field of spin chemistry and are likely to form the basis of the remarkable magnetic compass sense of birds and other animals.

This presentation will describe the basic physical chemistry underlying these magnetic effects using illustrative examples drawn from recent work performed in Oxford.

Speaker:

Elisabeth Rieper

Title:

Entanglement enhanced bird navigation

Abstract:

Using entanglement in biological systems offers great advantages. A good example is the radical pair mechanism. In that model migratory birds use maximally entangled states for navigating in earth magnetic field. But one has to distinguish between the classical correlation and the quantum correlation. A maximally entangled singlet state becomes after strong decoherence a strongly classically correlated state. I will talk about the role of entanglement and correlation in the radical pair mechanism. Although entanglement enhances bird navigation classical correlations seem to be sufficient. 

Session:      15 January, Thursday

Speaker:

Francois Fillaux

Title:

Some speculations on the impact of quantum mechanics on macromolecules of biological importance

Abstract:

Quantum mechanics explains structures, stereochemistry, and chemical properties of macromolecules. However, whether quantum mechanics could play a specific role in biological processes is highly controversial, for decoherence is anticipated to occur on a very short time scale (~ 10-13 s) in the environment of a living cell at room temperature.

In practice, the available computing power is not yet sufficient to envisage quantum calculations of macromolecules. It is a widespread assumption that complex mechanisms involved in the folding of proteins into their native structures can be represented by dynamics of classical nuclei in a multidimensional space. However, this leads to the famous Levinthal paradox.

As a highly speculative introduction to further discussions, I’ll refer to experimental studies of some hydrogen bonded crystals showing that open macroscopic systems are not necessarily doomed to decoherence and classicality. Decoherence-free macroscopic states and quantum interferences can be observed, even at room temperature. I’ll speculate on possible bridges between hydrogen bonded crystals and biological macromolecules, such as proteins or DNA’s.

Speaker:

Simon Benjamin

Title:

An organic quantum information technology

Abstract:

I will describe the efforts of researchers, based at Oxford and elsewhere in the UK, to create molecular scale structures for quantum information processing. We synthesis hierarchal carbon-based nanostructures, aiming to tailor them to support phenomena like long lived coherence and entanglement. I hope this will serve as an interesting concrete example of how quantum technology might work. Moreover it may help to crystalize questions as to what capabilities are possible, or impossible, with natural organic systems.

Speaker:

Judith Klinman

Title:

Hydrogen Tunneling: A Chicken vs. Egg Problem in Biological Catalysis

Abstract:

This talk will discuss the model for enzyme catalysis that has emerged as the result of the extensive evidence for hydrogen tunneling in these reactions. The underlying question will be whether quantum behavior has driven the evolution of the catalytic behavior of enzymes or whether the observance of quantum behavior is a consequence of the evolution of highly active enzymes.

Speaker:

Vasily Ogryzko

Title:

Quantum information processing at the cellular level. Euclidean approach.

Abstract:

The convergence of 'omics-' and 'nano-' technologies will lead to appreciation of two problems that molecular systems biology will have to address:

1. How to take into account the limits to how much can be observed concerning an individual biological object (e.g., single cell) and
2. How to explain stability of intracellular dynamics without much left for the 'coarse graining procedure', uncritically used to account for the stability of observed intracellular phenomena.

I discuss an approach to these problems based on the principles of quantum mechanics.

Speaker:

Anita Goel

Title:

Abstract: