Future Tense

Nature - Humans - Past - Future - Presence - Absence These familiar terms are the stepping stones of thought that went into my thesis work. While some may pair these words together as dichotomies, I concentrate on the balancing act that exists between them. Since the first Industrial Revolution beginning in the mid-18th century, human activities have significantly altered the rest of the natural world. Other species have evolved in reaction to circumstances produced by human actions. Through my own observations of nature and research into how humans have impacted nature’s evolution, speculation began to swell as to what does the future look like? My thesis work presents found objects from human life intermingled with my own ceramic pieces that are inspired by nature but have elements of peculiarity. The relics represent a human existence and the ceramic components act as a symbol of other forms of life. These familiar, yet odd growth forms imply futurity, a continued existence. This futurity is stemming from a human element that is clearly from the past, combined with this altered view of nature. Are humans of the past too? Are these growths something of the future? At a fundamental level, the work I make as an artist is intended to imply that life will continue in some form, with or without us. My work evokes a glimpse of how things may evolve in the future in order to stress the importance of mindful consideration of how the decisions we make impact the environment

On the Melting of Bosonic Stripes

We use quantum Monte Carlo simulations to determine the finite temperature phase diagram and to investigate the thermal and quantum melting of stripe phases in a two-dimensional hard-core boson model. At half filling and low temperatures the stripes melt at a first order transition. In the doped system, the melting transitions of the smectic phase at high temperatures and the superfluid smectic (supersolid) phase at low temperatures are either very weakly first order, or of second order with no clear indications for an intermediate nematic phase.Comment: 4 pages, 5 figure

Ferromagnetism of the 1-D Kondo Lattice Model: A Quantum Monte Carlo Study

The one dimensional Kondo lattice model is investigated using Quantum Monte Carlo and transfer matrix techniques. In the strong coupling region ferromagnetic ordering is found even at large band fillings. In the weak coupling region the system shows an RKKY like behavior.Comment: 9 pages 5 Postscript figures and the dvi and Postscript file of the paper are available by anonymous ftp from maggia.ethz.ch (directory: /reports/92-10

Solving the Quantum Many-Body Problem with Artificial Neural Networks

The challenge posed by the many-body problem in quantum physics originates from the difficulty of describing the non-trivial correlations encoded in the exponential complexity of the many-body wave function. Here we demonstrate that systematic machine learning of the wave function can reduce this complexity to a tractable computational form, for some notable cases of physical interest. We introduce a variational representation of quantum states based on artificial neural networks with variable number of hidden neurons. A reinforcement-learning scheme is then demonstrated, capable of either finding the ground-state or describing the unitary time evolution of complex interacting quantum systems. We show that this approach achieves very high accuracy in the description of equilibrium and dynamical properties of prototypical interacting spins models in both one and two dimensions, thus offering a new powerful tool to solve the quantum many-body problem

Cluster Monte Carlo Algorithms for Dissipative Quantum Systems

We review efficient Monte Carlo methods for simulating quantum systems which couple to a dissipative environment. A brief introduction of the Caldeira-Leggett model and the Monte Carlo method will be followed by a detailed discussion of cluster algorithms and the treatment of long-range interactions. Dissipative quantum spins and resistively shunted Josephson junctions will be considered.Comment: to be publushed in Proceedings of the Yukawa Symposium 200

Magnetization plateaux and jumps in a class of frustrated ladders: A simple route to a complex behaviour

We study the occurrence of plateaux and jumps in the magnetization curves of a class of frustrated ladders for which the Hamiltonian can be written in terms of the total spin of a rung. We argue on the basis of exact diagonalization of finite clusters that the ground state energy as a function of magnetization can be obtained as the minimum - with Maxwell constructions if necessary - of the energies of a small set of spin chains with mixed spins. This allows us to predict with very elementary methods the existence of plateaux and jumps in the magnetization curves in a large parameter range, and to provide very accurate estimates of these magnetization curves from exact or DMRG results for the relevant spin chains.Comment: 14 pages REVTeX, 7 PostScript figures included using psfig.sty; this is the final version to appear in Eur. Phys. J B; some references added and a few other minor change