The job of a theoretical physicist is to make mistakes as fast as possible. — John A. Wheeler
The simplest way to see what I have been up to in research is to look at the abstracts of my papers, preferably reverse-sorted by time (latest first) which you can find by looking on my Google Scholar page.
I have been stuck with thinking about entropy since I was a kid, for some reason, probably because I don’t fully understand it yet. I have focused in particular on the connection between nonlinearity and entropy dynamics, which is via an information-theoretic perspective. Thinking this way provides a powerful unifying perspective on all sorts of dynamical systems and behavior. An early thinker about chaos and entropy issues in physics was Ilya Prigogine of Bruxelles and Austin, and there was some really interesting work done by Rolf Landauer on the idea that ‘information is physical’. More recent gurus are Carl Caves and Wojciech Zurek. Remarkably, as I’ve found over the years, thinking about entropy turns out to have more practical applications as well. This is different from the usual equating of entropy to chaos and disorder.
A lot of my recent work has been about slow-moving projects in quantum mechanics, and some faster-moving projects in nonlinear dynamics and complex systems, particularly in the context of a statistical physics approach to a biophysics problem in development: If the entropy of the Universe is always increasing then how does a biological system get more ordered ?
The bulk of my career has been about quantum nonlinear dynamics, especially in open systems and quantum composite systems, including quantum information. I was lucky enough to have begun a conversation with Ivan Deutsch about such things at a conference early in both our careers. While we never published that work on entanglement it led in the long run to my Carleton group being a node of SQuInT. This is a particularly impactful scientific network that has been part of the transformation in our understanding and control of quantum mechanics and quantum information. Several former students are now part of the quantum information industry — the size, scale, and probably very existence of which I would have found hard to credit 25 years ago.
My focus has been on more foundational questions. Some of it used to be about how the time-scales for quantumness (`decoherence rates’) are set by how isolated you can make the system that you are looking at from all other systems, i.e. `the rest of the Universe’ but also the nonlinearity of the dynamics. As a result or in general my work has landed up exploring techniques and results in the behavior of quantum and classical probability dynamics in nonlinear (possibly chaotic) systems and understanding the interplay of three different kinds of ‘probabilistic’ behavior — stochastic or random, chaotic, and quantal.
I have had a great deal of fun over my career exploring classically and quantum systems with this as well as nonlinear ideas in general especially when collaborating and interacting with scientists with different backgrounds and interests. Some projects included collaborations with experimentalists in atomic physics (the kicked Rydberg atom, and the Lithium 7 Bose condensate), some analysis of 2-d fluid dynamics experiments, work with chemical physicists, as well as laser dynamicist etc. Current conversations are with developmental biologists, for example.
I am always looking for students with whom to talk about such issues — short or long-term projects welcome.
Tools: I am a pen and paper theorist who believes that numerical experiments on computers to enhance intuition, verify analysis and in general serve as a ‘third way’ of understanding nature. As problems get more complex, computational tools are by definition more important. Now that AI is upon us, I look forward to seeing where this goes.
A VERY OLD Summary of previous work including a list of co-authors.
Hunting quantum butterflies: The quantum-classical transition for chaotic systems [Online talk (2007) at the Kavli Institute for Theoretical Physics, Santa Barbara]Coherence and decoherence in nonlinear Hamiltonian dynamics [Online talk (2003) at the Kavli Institute for Theoretical Physics, Santa Barbara]
Chaos, quantum mechanics and noise: Some answers, more questions [Notes for a talk 11/98].
Students: You’d be surprised at how little formal training you need before you can get plugged in.