A project of the Theoretical Chemical and Quantum Physics Group

Team

Mr. David Ing, Dr. Nicolas Vogt, Dr. Jan Jeske, A/Prof. Jared Cole

Collaborators

M. Marthaler, G. Schön: Karlsruhe Institute of Technology

S. Huelga, M. Plenio: University of Ulm

C. Müller, T. Stace: University of Queensland

Brief Project Outline

What defines the boundary between the quantum and classical worlds is one of the most fundamental questions of modern physics. Quantum theory has proven to be spectacularly successful at small length scales, short times and very cold temperatures. Yet, in our everyday world the equations of classical physics have a fundamentally different form and interpretation. How do we smoothly swap between these descriptions? - this is one of the central points of decoherence theory. How do we perturb an otherwise phase coherent theory (quantum mechanics) in order to include the effects of the wider environmental, ie. the effects of dephasing and dissipation.

The TCQP group studies this problem in a range of different physical systems and with several different mathematical techniques. Problems of current interest include:

  • Mathematical methods for describing spatial correlations in noise processes and there ramifications of these correlations in quantum system dynamics
  • The cross-over from Markovian to non-Markovian dynamics and the effects of finite bath effects
  • Extensions to the usual decoherence models for more efficient and scalable numerical simulation

A linear chain of spins is an ideal system to study effects due to spatially correlated noise. Here we show the transmission probability of so-called "perfect state transfer" as a function of correlation length of environmental dephasing.  We see that for noise which is correlated on length scales longer than the spin chain, the noise has little effect on the excitation transfer process.

The distribution of charge states in an single-electron transistor evolving as a function of time, computed using stochastic Bloch-Redfield theory. As the system evolves, the statistical distribution of charge states broadens due to the interplay of coherent and incoherent processes which are modelled consistently within a stochastic master equation.

Recent Publications

J. Jeske and J. H. Cole, Derivation of Markovian master equations for spatially correlated decoherence, Physical Review A 87 052138 (2013)

J. Jeske, N. Vogt and J. H. Cole, Excitation and state transfer through spin chains in the presence of spatially correlated noise, Physical Review A 88 062333 (2013)

N. Vogt, J. Jeske and J. H. Cole, Stochastic Bloch-Redfield theory: Quantum jumps in a solid-state environment, Physical Review B 88 174514 (2013)

For more information about this project, please contact Jared Cole.