Measurement of Quantum Scrambling with Trapped Ions


Kevin Landsman (JQI)
March 16, 2018
CSS 3100A

Trapped ion crystals are a promising technology for building large-scale quantum computers, which may be able to simulate inaccessible physical systems like black holes. Quantum scrambling occurs when local information disperses into quantum many-body correlations and describes an interpretation of the black hole information problem. Out-of-time-ordered correlation functions (OTOCs) have recently emerged as a way to directly measure quantum scrambling. In the presence of quantum scrambling, an OTOC will decay to 0, but decoherence and imperfect Hamiltonian evolution errors will also cause the OTOC to decay to 0, underlying the problems inherent in such a measurement. Here, we implement a quantum teleportation scheme that simultaneously measures an OTOC while projecting the presence of scrambling onto the teleportation fidelity. The scrambling operation is realized by a three-qubit quantum gate. Measured teleportation fidelities are typically 78%, which act as a bound for the ''true" scrambling-induced decay of the OTOC. 

Note: There will be snacks and drinks at 4:00 and the talk is from 4:10 to 4:40 in CSS 3100A (Please note the change in venue!)