School of Physical and Chemical Sciences Seminar Series

A Tale of Tiny Photons and Quantum Jumps


Howard J. Carmichael


Dodd-Walls Centre for Photonic and Quantum Technologies, University of Auckland, New Zealand

Time & Place

Fri, 29 Sep 2017 11:00:00 NZDT in Rutherford Room 531, level 5

All are welcome


The evolving status of quantum jumps is a tale that reaches back 100 years. Beginning with the atomic model of Bohr, jumps between energy levels were a staple of the old quantum theory. Bohr’s jumps were soon challenged, however, by Schrödinger’s wave equation, where nothing “jumps”. Yet in the mid-1980s, quantum jumps were observed [Nagourney et al., Phys. Rev. Lett. 56, 2797 (1986); Sauter et al., Phys. Rev. Lett. 57, 1696 (1986); Bergquist et al., Phys. Rev. Lett. 57, 1699 (1986)]. My talk will revisit this history, and, in particular, ask whether the experiments from the 1980s observe quantum jumps that actually “jump”. A surprising path to an answer will be provided, where the anatomy of the quantum jump can be tracked over time in an experiment that employs microwave photons and an artificial atom fabricated from Josephson junctions.