Event Details

Condensed Matter webinar

We consider irreversibility in the sense of cooking an egg. One turns the heat up, then back down, but the egg does not return to its initial raw state, even if the heating and cooling is arbitrarily slow and gradual. Instead the slow external parameter change induces a spontaneous transition to a qualitatively different cooked state, and this transition is not undone by undoing the slow parameter change that caused it.

Analogous processes can be defined for any dynamical system, so what is the microscopic limit of this egg-cooking form of irreversibility? One might suppose that microscopic analogs of “raw” and “cooked” states exist, but differ from each other only infinitesimally in the microscopic limit, with the difference becoming greater with increasing system size. We show with explicit examples that this need not be the case: after an arbitrarily slow forward-and-back parameter sweep, even a single degree of freedom can return to a final state drastically different from its initial state. Whether this “cooking” transition happens depends sensitively on initial conditions, however. What increases with system size is the fraction of initial states for which the irreversible transition occurs. When small eggs become cooked, they are just as thoroughly cooked as macroscopic eggs, but the chance of cooking a small egg is small.

After presenting that minimal example I will use slightly more complicated models to illustrate possible additional effects of quantum mechanics and dynamical chaos in the microscopic onset of irreversibility.

References:

"How to probe the microscopic onset of irreversibility with ultracold atoms"

Ralf Bürkle, Amichay Vardi, Doron Cohen, James R. Anglin, Sci. Rep. 9, 4169 (2019).

"Probabilistic Hysteresis in Integrable and Chaotic Isolated Hamiltonian Systems"

Ralf Bürkle, Amichay Vardi, Doron Cohen, James R. Anglin, Phys. Rev. Lett. 123, 114101 (2019).

"Probabilistic Hysteresis in an Isolated Quantum System: The Microscopic Onset of Irreversibility from a Quantum Perspective"

Ralf Bürkle, James R. Anglin, Phys. Rev. A 101, 042110 (2020).

"Probabilistic hysteresis from a quantum-phase-space perspective", Ralf Bürkle and James R. Anglin

Phys. Rev. A 102, 052212 (2020).

If you have not received a Teams link for this event and would like to attend, please contact Dr. Michael Thompson.