Quantum criticality, quenches and the Loschmidt echo

by Prof. Amit Dutta (IIT Kanpur)

Tuesday 29 Oct 2013, 14:30 → 15:30 Asia/Kolkata

AG69 (Colaba Campus)

I shall introduce the notion of the Loschmidt echo using the central spin model in which a central spin (qubit) is globally coupled to a spin chain. I shall indicate how does the Loschmidt echo behave close to a quantum critical point and how it is also related to the decoherence of the central spin which was initially in a pure state. Finally, I shall discuss at some length the behavior of the echo when the spin chain is driven across a quantum critical point suddenly or slowly.