93rd Statistical Mechanics Conference

    Abstracts of Long Talks


    Larry Abbott, Brandeis University
    "Spontaneous and Evoked Activity in Neural Networks"

    Neural network modeling is often concerned with stimulus driven responses, but most of the activity in the brain is internally generated. I will discuss models of spontaneously generated activity and the relationship between internally and externally generated responses. In particular, I will address how evoked activity, signaling events in the real world, propagates through and can be distinguished from ongoing spontaneous activity.
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    Mark Alber, University of Notre Dame
    "On Three-Dimensional Modeling of Myxobacteria Aggregation and Morphogenesis"

    Myxobacteria are a model system for studying cell-cell interaction and organization preceeding differentiation. When starved, tens of thousands of Myxobacteria cells change their motility, align, stream and form aggregates, which then develop into fruiting bodies. While cell aggregation has canonically been modeled as the result of chemotaxis, growing evidence shows that Myxobacteria organization depends on a contact-mediated cell signaling mechanism. In this talk we will describe the first three-dimensional model of cell aggregation in Myxobacteria based on a short-range cell-cell communication. We will demonstrate that the same 3D discrete stochastic model simulates for different values of parameters, all stages of myxobacteria aggregation: the formation of a traffic jam, which then triggers formation of an aggregation center culminating in a fruiting body formation.
    In the second half of the talk we will present a computational model of the developmental phenomena.To illustrate general approach, we will describe a simulation of the skeletal pattern in a growing embryonic vertebrate limb.
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    D. Ceperley, University of Illinois Urbana-Champaign
    "Can Metallic Hydrogen be a Ground State Liquid?"

    There has been a suggestion by Ashcroft that hydrogen might melt at pressures high enough to convert the molecules into atoms. If the melting temperature was low enough, one could have a 2 component superconductor, that is were both the electrons and protons could pair up. We use a recently developed Quantum Monte Carlo method to investigate the melting temperature of high density hydrogen and to assess how likely this scenario is.
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    Lincoln Chayes, UCLA
    "Ordering Due to Spin-Waves (AKA Order by Disorder)"

    Certain spin-systems, including some deemed to be of relevance to the question of orbital ordering in transition metal compounds are (mathematically) studied. These systems have highly degenerate ground states characterized by a continuous symmetry. Notwithstanding their infrared behavior, spin-wave excitations are shown to stabilize certain states ("order due to disorder") and multiple phases are established.
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    Phillipe Choquard, Institute of Theoretical Physics, EPFL
    "On a class of exactly integrable radial solutions of the continuity and Euler's equations for nD systems with long range interactions"

    Hamiltonian fluids with Newtonian or Coulombian self-interactions in nD. are considered here.Exact integrability of radial solutions of the corresponding Euler,.Poisson and continuity equations is shown to result from the existence of two constants of integration. Representative exemples of implicit solutions are given for the pure attractive and repulsive systems,for the models with homogenous and compensating background densities, i.e. the One Component Plasma and the model of Cold Dark Matter in an expanding universe .
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    Daan Frenkel, FOM Institute for Atomic and Molecular Physics
    "From one to zero: minimal models in molecular dynamics"

    The hard sphere model has become the reference model for all simple fluids. However, there exist even simpler models that exhibit non-trivial dynamic (and sometimes, static) behavior. In my talk I will discuss the interesting properties of systems of particles that have vanishing volume, or even vanishing excluded volume. I hope to show that, also in the world of models, there is plenty of room at the bottom...
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    S. Goldstein, Rutgers University
    "Einstein, Hidden Variables, and Nonlocality"

    In 1935 Einstein, Podolsky, and Rosen argued that the quantum mechanical description is incomplete, i.e., that there are hidden variables. Bell showed in 1964 that the EPR argument is fundamentally flawed. However, in so doing Bell also provided strong support for the conclusion of that argument.
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    A. B. Harris, University of Pennsylvania
    "Two Topics: a) 1/d Expansion for k-core Percolation, b) Ferroelectric Incommensurate Magnets"

    ABH and J. M. Schwarz (cond-mat/0505329) treat bootstrap or k-core percolation. On the Bethe lattice the transition has a hybrid structure in which the order parameter is discontinuous while the correlation length diverges. Our goal is to determine whether or not this hybrid structure survives in finite dimension d. To do this we calculate terms of relative order 1/d^3 for the critical coupling constant of the discontinuity and for the coupling constant at which the correlation length diverges. Since we find these two thresholds to be identical, we suggest that the hybrid structure is maintained for some range of large d.

    In the collaboration of cond-mat 0503385 we develop a Landau theory to treat systems like Ni_3V_2O_8 in which ferroelectricity appears in a phase transition simultaneously with incommensurate magnetic order. We show that a trilinear coupling of the spontaneous polarization, P, to the Fourier components M(q) and M(-q) of the magnetization has the correct symmetry to explain why P appears in only one of the incommensurate magnetic phases and why, when P is nonzero, it can only have a component along a certain crystallographic axis.
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    Hans J. Herrmann, Institute for Computational Physics, University of Stuttgart
    "Searching for the perfect packing"

    Extremely dense granular packings are needed for high resistance concrete or hard ceramics. They can only be realised when the size distribution of grains is strongly polydisperse. Typically powerlaw distributions give the best results. I will present simple packing models for polydisperse distributions like a parking lot model for different sizes. I will also discuss the perfect limit of Apollonian packings in three dimensions and show in particular the existence of space filling bearings rotating without slip and without torsion.
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    Bernard Jancovici, Université de Paris-Sud
    "The Casimir effect in some classical (i.e. non-quantum) situations"

    We consider the Casimir effect for conductors microscopically modelled as made of charged particles, in equilibrium classical (i.e. non-quantum) statistical mechanics. The particle-radiation coupling can be eliminated (Bohr-Van Leeuwen theorem) and only the static Coulomb interaction remains. In the simple case of two conducting parallel plates separated by vacuum, the Casimir long-range attractive force between the plates (due to the coupled thermal fluctuations inside the plates) is found to have only half the value found by the standard calculation which describes the walls macroscopically as ideal inert conductors. If an electrolyte is present between the plates, the Casimir force is screened into a, still attractive, short-range force. We also consider, in two dimensions, a disc with a conducting wall. When the inside of this disc is empty, the grand potential of the wall has a universal logarithmic finite-size correction. When the disc is filled by a conducting fluid, this universal term is "screened" away.
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    Kai Kadau, Lawrence Livermore National Laboratory
    "Nanohydrodynamics Simulations: An Atomistic View of the Rayleigh-Taylor Instability"

    We introduce the concept of nanohydrodynamics simulations-hydrodynamics on the nanometer and nanosecond scale by molecular dynamics simulations for up to 100 million particles. Nanohydrodynamics simulations performed on the latest generation of supercomputers exhibit Rayleigh-Taylor instability---the mixing of a heavy fluid on top of a light in the presence of a gravitational field---initiated by thermal fluctuations at the interface, leading to the chaotic regime in the long-time evolution of the mixing process. The early-time behavior agrees with linear analysis of continuum theory (Navier-Stokes), and the late-time behavior agrees quantitatively with experimental observations. Nanohydrodynamics provide insight into the turbulent mixing process that is inaccessible to either continuum calculations or to experiment.
    [1] Proc. Natl. Acad. Sci. 101, 5851 (2004), Nanohydrodynamics simulations: An atomistic view of the Rayleigh-Taylor instability by K. Kadau, T.C. Germann, N.G. Hadjiconstantinou, P.S. Lomdahl, G. Dimonte, B.L. Holian, and B.J. Alder.
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    M.H. Kalos, Lawrence Livermore National Laboratory
    "Fermion Monte Carlo"

    It has been known for some decades that accurate numerical integration of the many-body Schrodinger Equation for continuous bosonic systems is straightforward. In imaginary time, it is a diffusion equation that is easily modeled by numerical random walks-- that is, by Monte Carlo methods. Integrating the many-fermion equation without uncontrolled approximations is much more difficult; the challenge has come to be called the "fermion sign problem."
    I will review the nature of the algorithmic difficulties and explain how an understanding of those challenges presents opportunities for solving them. Specifically I propose the following modifications to Diffusion Monte Carlo:
    A population of pairs of positive and negative walkers is generated. Guiding functions are used that distinguish between positive and negative walkers: that is, an algorithmic symmetry is broken. When walkers of different signs branch differently new pairs are created by applying a pair permutation. The "diffusion" steps of the walkers in a pair are correlated so that the walkers can meet in any number of dimensions. Walkers in a pair that come close can be canceled in a way that preserves the future value of any projection with an antisymmetric function.
    The method has been applied to some small dimers, to a two-dimensional electron gas, and to systems of He-3.
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    Tom Kennedy, University of Arizona
    "Monte Carlo comparisons of the 2d self-avoiding walk and SLE"

    The scaling limit of the two dimensional self-avoiding walk (SAW) is believed to be SLE with parameter 8/3. In this conjecture the SAW and SLE curves are treated as subsets of the plane, i.e., not as parameterized curves. Past Monte Carlo simulations have supported this conjecture. In this talk we consider the SAW and SLE as parameterized curves and attempt to compare random variables that depend on the parameterization.
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    Jonghoon Lee & Anthony J.C. Ladd, University of Florida
    "Axial Segregation of a Settling Suspension in a Rotating Cylinder"

    A suspension of non-neutrally buoyant particles, contained in a horizontal cylinder, can be unstable to axial perturbations in concentration if the cylinder is rotated at an appropriate angular frequency. A highly regular pattern of particle density and fluid flow coexist in a non-equilibrium stationary state. The density profile along the cylinder axis is roughly sinusoidal, with a well-defined wavelength equal to the cylinder diameter and a magnitude of approximately 30% of the average number density. Similar patterns were observed in laboratory experiments under similar conditions (Matsen et al. Phys. Rev. E., 67:050301, 2003). We have used numerical simulations within the Stokes-flow approximation to investigate the mechanism underlying axial band formation. Our results show that bands develop from an inhomogeneous particle distribution in the radial plane, which is itself driven by the competition between gravity and the viscous drag of the rotating fluid. We have discovered that the mean angular velocity of the particles is an order parameter, which distinguishes between a low-frequency segregated phase and a high-frequency dispersed phase, where the particles fill the whole volume uniformly. The order parameter is a function of a single dimensionless frequency, which shows that a characteristic length is the mean interparticle separation. As the rotational frequency increases, the particle distribution becomes more homogeneous, and the band structure disappears. Hydrodynamic diffusion stabilizes the suspension against centrifugal forces, allowing for a uniformly dispersed phase that can be used to grow three-dimensional cell cultures in an artificial microgravity environment.
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    Elliott Lieb, Princeton University
    "Rigorous results on the ground state energy of Bose gases, including Bose Einstein Condensation"

    This will be a very brief review of work with R. Seiringer, J.P. Solovej and J. Yngvason on dilute Bose gases (especially gases in traps) and on charged bose gases. For dilute trapped gases (even rotating gases) the Gross-Pitaevskii equation is shown to be valid and there is 100% Bose-Einstein condensation into the solution of this equation.
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    Rafael de la Llave, University of Texas
    "Recent Progress in Geometric Mechanisms for Arnold Diffusion"

    Mechanical systems which are isolated conserve energy. When the systems are subject to periodic fields with zero average it can happen that the effects average out or it can happen that they accumulate and there are large consequences. There are rigorous mathematical results that tell that the forces average out for a large set of initial conditions (KAM theory) or for a large time (Nekhoroshev theory). Nevertheless, there are other phenomena -- usually called diffusion -- which are important conceptually and for many applications (e.g. plasma confinement, accelerator physics, chemistry) In this talk we plan to survey some recent results obtained by A. Delshams, T. M-Seara and the author in identifying geometric structures by which the perturbations can indeed accumulate. The analysis is based in identifying and computing geometric structures that allow instability to happen. These structures are generated by resonances, confirming the physical intuition.
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    Michel Mareschal, ULB
    "Simulation of Lamellar Phases"

    MD is being used to simulate lamellar phases formed by amphiphilic molecules. The elastic properties of the membranes are investigated , allowing to delimitate the validity of the method. Defects are then studied and comparison with a model reported. The interaction with a model-polymer is also examined.
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    Alan Middleton, Syracuse University
    "Optimization for Physics and the Physics of Optimization"

    The study of statistical mechanical models with quenched disorder has historically been closely tied with optimization algorithms developed in computer science. I will review this connection and then give two examples where a "physical" understanding of an algorithm for optimization is useful: (1) a Griffiths type of singularity in a hard optimization problem related to spin glasses and (2) annihilation dynamics in an algorithm for the random field Ising magnet. These results show how we can learn more about the physics AND the algorithms by using methods from each field.
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    Erik E. Santiso, Keith E. Gubbins
    Department of Chemical Engineering, North Carolina State University, Raleigh, NC 27695-7905, USA
    Aaron M. George, Marco Buongiorno Nardelli
    Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
    Malgorzata Sliwinska-Bartkowiak
    Institute of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan, Poland

    "Effect of confinement on chemical reactivity"

    Reactions are frequently carried out in nano-structured media, such as nano-porous media, micellar solutions, and nano-composites; such environments can enhance reaction through high surface area, interactions with the nano-structure and confinement effects. At present there is little understanding of the role of nano-structure in many such reactions. Experimental measures of compositions and rates reflect an integration over multiple catalytic effects, and so provide little fundamental understanding. In the present work, we focus on one important class of nano-structured media, namely nano-porous carbons. In such environments mechanisms and reaction rates are strongly influenced by a number of factors, including reduced dimensionality, selective adsorption, chemical heterogeneity of the pore surfaces, diffusion limitations, and strong electronic interactions with the walls. These factors can modify the potential energy surface, and therefore the reaction mechanism. Such confinement effects have recently been shown to have a major influence (up to two orders of magnitude for the systems studied) on both reaction yields and rates for many reactions , , and in some cases on the reaction mechanism. A clear understanding of these factors could lead to the design of much improved catalytic systems, and it may be possible to optimize both the yield and rate of the reaction. We report results of ab initio and semi-classical statistical mechanics calculations showing the effect of confinement within nanoporous carbons on two different classes of reactions: (1) unimolecular decomposition of small organic molecules and (2) interconversion between rotamers of small hydrocarbons. For these reactions, confinement can affect the reaction mechanism through both catalytic interactions with the carbon surface and geometrical constraints. We also show the effect of confinement on the free energy profile for the reaction and the kinetic rate constants.
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    C.H. Turner, J.K. Johnson and K.E. Gubbins, J. Chem. Phys. 114, 1851 (2001); C.H. Turner, J. Pikunic and K.E. Gubbins, Mol.Phys. 99, 1991 (2001); C.H. Turner, J.K. Brennan, J.K. Johnson and K.E. Gubbins, Journal of Chemical Physics, 116, 2138-2148 (2002); C.H. Turner and K.E. Gubbins, Journal of Chemical Physics, 119, 6057-6067 (2003); E.E. Santiso, A.M. George, C.H. Turner, M.K. Kostov, K.E. Gubbins, M. Buongiorno-Nardelli and M. Sliwinska-Bartkowiak, Applied Surface Science, in press (2005). O. Byl, P. Kondratyuk and J.T. Yates, Jr. J. Phys. Chem. B, 107, 4277 (2003).
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    Marlan Scully, Texas A&M University
    "From Bose and Einstein to Bogoliubov and Beyond: a rich tradition of optical and statistical physics"

    The current studies of Bose Einstein Condensation (BEC) and coherent atom optics draw from and contribute to the general subject of coherence effects in many body physics and quantum optics. It is in this spirit that the present talk sketches some recent application of techniques, ideas, and theorems which have been developed in understanding lasers and squeezed states to the condensation of N Bosons. Highlights of these studies, and related points of BEC history to be discussed are:

    The rich and fruitful interaction between optical and statistical physics begins with Bose's famous paper [1] entitled:
    "The Planck Law and the Hypothesis of the Light Quanta" Concerning which, the translator (Einstein) writes:
    "Note added by the translator: Bose's derivation of Planck's formula constitutes, in my opinion, an important step forward. The methods used here also yields the quantum theory of the ideal gas, as I will explain elsewhere." [2]
    However, as was early on noted by Uhlenbeck, [3] the physics of BEC, even for the ideal gas, is subtle with many pitfalls and surprises. In the following we cite a few such difficulties, and indicate how we resolve them.
    Uhlenbeck criticized Einstein's arguments concerning the implied singularity in the equation of stateTc. Kahn and Uhlenbeck [4] later pointed out that the "discussion of the condensate requires that the bulk limit be taken in which the number and volume are made infinite with the density, N/V fixed." But this leaves open the question of how best to think about and define Tc for finite mesoscopic systems. We show [5] that it is useful to follow the lead of laser theory [6] wherein the critical threshold inversion is defined as that for which gain equals loss. Similarly, in recent work we showed that the critical temperature Tc is the temperature at which the rate of addition of atoms to the condensate (cooling) equals the rate of ejection (heating), and this holds for mesoscopic systems.
    Furthermore Ziff, Uhlenbeck, and Kac [7] note that "[When] the grand canonical properties for the ideal Bose gas are derived, it turns out that some of them differ from the corresponding canonical properties-even in the bulk limit!" In the present work we have derived all moments of the condensate above and below Tc using the canonical ensemble. The results are in good agreement with numerical simulation. [8]
    As late as 1997 Herzog and Olshanii [9] noted that there was no known simple analytical expression for the canonical partition. We now find a simple analytical expression for the canonical partition function in terms of the incomplete gamma function. [5]
    Thus we find that the quantum theory of the laser and the laser phase transition analogy yields a treatment of BEC, which provides a resolution to the above three problems (and much more), and is in excellent agreement with computer simulation.
    Concerning the interacting Bose gas, Bogoliubov [10] made a giant step forward providing the first microscopic description of the superfluid flow of HeII. Furthermore, the Bogoliubov quasi particle operators and have long been touted as being an early example of the operator algebra of squeezed states of the radiation field.
    Turning the tables, we have recently shown how certain theorems developed in the study of squeezed states of the radiation field make it possible to obtain the partition function for the interacting Bose gas in the Bogoliubov limit for the first time [11]. An important conclusion from this work is that the ground state occupation shows fluctuations, which are not Gaussian even in the thermodynamic limit. Furthermore, we clearly establish the fact that fluctuations in the interacting gas are closely related to those of the ideal gas but reduced by one half. Physically, this is due to the fact that the atoms are strongly coupled in correlated pairs such that the number of degrees of freedom is only ˝ N, not N as in the ideal gas.

      1. D. Bose, Z. Phys. 26, 178 (1924)
      2. A. Einstein, Preuss. Akad. Wiss, Jan. 1925 p1.
      3. G. Uhlenbeck, Ph.D. Thesis, Leiden 1927
      4. B. Kahn and G. Uhlenbeck, Physica 5, 399 (1938)
      5. M. Scully, Phys. Rev. Lett. 82, 3927 (1999)
      6. V. DeGiorgio and M. Scully, Phys. Rev. A2, 1170 (1970); R. Graham and H. Haken, Z.Phys. 237, 31 (1970)
      7. R. Ziff, G. Uhlenbeck, and M. Kac, Phys. Rev 32, 169 (1977)
      8. V. Kocharovsky, M. Scully, S-Y Zhu, and M. Zubairy, Phys. Rev. A61, 023609-1 (2000)
      9. C. Herzog and M. Olshanii, Phys. Rev. A55, 3254 (1997)
      10. N. Bogoliubov, Physica 26, 51 (1960)
      11. V. Kocharovsky, Vl. Kocharovsky, and M. Scully, Phys. Rev. Lett. 84, 2306 (2000); Phys. Rev. A61, 053606-1 (2000)
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      Robert Seiringer, Princeton University
      "A Stronger Subadditivity of Entropy"

      The strong subadditivity of entropy plays a key role in several areas of physics and mathematics. It states that the entropy S[\rho]= - Tr (\rho \ln \rho) of a density matrix \rho_{123} on the product of three Hilbert spaces satisfies S[\rho_{123}] - S[\rho_{23}] \leq S[\rho_{12}]- S[\rho_2]. We strengthen this to S[\rho_{123}] - S[\rho_{12}] \leq \sum_\alpha n^\alpha (S[\rho_{23}^\alpha ] - S[\rho_2^\alpha ]), where the n^\alpha are weights and the \rho_{23}^\alpha are partitions of \rho_{23}. As applications we prove some monotonicity and convexity properties of the Wehrl entropy and entropy inequalities for quantum gases. This is joint work with Elliott Lieb.
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      George Stell, SUNY at Stony Brook
      "What's new in liquid-state TPT"

      After noting Berni Alder's key role in initiating the use of liquid-state thermodynamic perturbation theory, we go on to briefly survey current developments in the field.
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      Eric Vanden-Eijnden, NYU/Courant Institute
      "Minimum Free Energy Paths, Blue Moon Sampling, and String Method"

      We will discuss a strategy to identify the reaction coordinate of an activated process using a set of predefined coarse variables relevant for the reaction. The method build on a generalization of the blue moon sampling method which allows one to calculate the free energy in multiple dimension, and the string method which allows one to identify the optimal transition pathways in the free energy landscape. Quite interestingly, the optimal transition pathways, which we refer to as minimum free energy paths, are not the minimum energy paths on the free energy landscape: these paths also depend on some mobility tensor accounting for dynamical effects.
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      Manuel Velarde, Instituto Pluridisciplinar, UCM
      "The Transition from Linear to Nonlinear Solitonic Electric Conduction in a Dissipative Toda Lattice"

      Oscillations and waves (linear and otherwise) and, eventually, solitons can be excited and maintained in the presence of dissipation provided we have an appropriate energy supply, hence an appropriate input-output energy balance. The idea goes back to Lord Rayleigh (1894) and it is very much like when steady structures are maintained by an appropriate energy balance. Hence the coinage "dissipative structures" (Nicolis & Prigogine, 1977), for steady patterns, and "dissipative solitons", for the corresponding nonlinear waves (steady structures in the commoving frame) with soliton-particle-like behavior on collisions and wall reflections (see, e.g., Nekorkin & Velarde, 2002; Nepomnyashchy & Velarde, 2002). I shall report on recent findings about a transition from linear electric conduction to a form of high-T superconduction, purely classical, occurring in a 1D Toda lattice, when an appropriate energy supply is incorporated, and hence an appropriate energy balance maintains the (Toda) dissipative solitons (cnoidal waves). The solitons (mostly lattice compressions) together with the ion-electron Coulomb interaction eventually bind dynamically the electrons (solectrons, in short) in the course of evolution of the waves in the presence of an external electric field. The characteristics current-field and current-temperature would be provided.
      Nekorkin, V. I. & Velarde, M. G., Synergetic Phenomena in Active Lattices. Patterns, Waves, Solitons, Chaos, Springer-Verlag, Berlin, 2002 (and references therein). Nepomnyashchy, A. A. & Velarde, M. G., Interfacial Phenomena and Convection, CRC-Chapman & may, London, 2002, Chapter 5. Nicolis, G. & Prigogine, I., Self-Organization in Nonequilibrium Systems, Wiley, New York, 1977. Rayleigh, Strutt, J. W. (Lord), The Theory of Sound, original 1894, reprinted by Dover, New York, 1945, Vol. 1, Sec. 68a. Velarde, M. G., Ebeling, W & Chetverikov, A. P., Int. J. Bifurcation & Chaos, to appear (2005).
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      Ned Wingreen, Princeton University
      "Modeling the chemosensing system of E. coli"

      The chemotaxis network in E. coli is the best studied signal-transduction network of any living organism. The network enables E. coli to swim toward attractants such as amino acids or sugars, and away from repellents. The cells perform chemotaxis by detecting temporal changes in their chemical environment and transducing this information into a decision to swim straight or change direction (tumble). The system is remarkable for its high sensitivity and robust adaptation over a wide range of external chemical concentrations. Motivated by recent in vivo FRET studies [1], we model the chemosensing system as a mixed array of interacting receptors akin to an Ising lattice. Our results support and extend the robust-adaptation model of Barkai and Leibler [2], in which receptor complexes function as two-level systems.
      [1] V Sourjik and HC Berg, PNAS 99(1), 123-127 (2002); Ibid, Nature 428(6981), 437-441 (2004).
      [2] N Barkai and S Leibler, Nature 387(6636), 913-917(1997).
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      J. Yepez, Air Force Research Laboratory
      "Quantum computation of nonlinear classical dynamics"

      I will present a few recent results on modeling various classical nonlinear systems using quantum information processing. As a starting point, I use a microscopic quantum mechanical system of spin-1/2 nuclei as an archetype quantum information processor: each spin-1/2 nucleus encodes a qubit and the secular dipolar Hamiltonian for spin-1/2 nuclei pairs encodes the operation of 2-qubit quantum logic gates. The spatial and temporal dynamics of the spin system is described at three physical scales: the microscopic, mesoscopic, and macroscopic scales. Periodic measurement of the quantum state of the microscopic spin system serves as a mechanism to break strict unitarity of the temporal evolution. The mesoscopic scale statistical description includes an analytically derivable entropy function and an H theorem and a quantum Boltzmann equation obeying detailed-balance. Then, by taking moments of the quantum Boltzmann equation, I analytically predict the macroscopic scale behavior of the spin system is governed by a classical effective field theory with dissipative terms. Macroscopic dissipation and nonlinearity ultimately arise by continually measuring the microscopic quantum state. By altering the microscopic Hamiltonian for spin-1/2 nuclei pairs, it is possible to recover different macroscopic classical effective field theories, which include the Burgers equation, the magnetohydrodynamic equations, the Navier-Stokes equation, and the Korteweg de Vries equation for example. I will present some recent simulation data obtained from nuclear magnetic resonance spectroscopy of liquid chloroform to illustrate the experimental technique for modeling classical nonlinear dynamics using this kind of quantum information processing. I will also present some numerical simulations using the quantum Boltzmann equation implemented directly on classical computers to illustrate how the method can be used today as a practical tool for computational physics.

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