Department of Physics, Engineering Physics & Astronomy

Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

CMPO Seminar - Quantum Jumps that Don’t!

Professor Howard Carmichael,
University of Auckland,
New Zealand

Date: Tuesday October 22nd
Time: 3:30pm
Location: Nanophotonics Collaboration Lab (261A)

Abstract:

Quantum jumps are emblematic of all things quantum. Certainly that is so in the popular mind…and more than an echo from the past, “quantum jumps” still hold a prominent place in the lexicon of physics today. What, however, is the character of these “jumps” on close inspection? Discontinuous and discrete, as in Bohr’s original conception…or perhaps a version of Schrödinger’s continuous evolution, which might be “tracked”, even interrupted and turned around? This seminar re-visits the jumps of single trapped ions from the mid-1980s [1] where quantum trajectory theory favours the latter option. I present the theoretical prediction and its recent experimental verification [2]: real-time monitoring tracks the jumps of an artificial atom in a superconducting circuit—the continuous path is reconstructed and the jumps interrupted and turned around.

[1] W. Nagourney et al., Phys. Rev. Lett. 56, 2797 (1986); T. Sauter et al., Phys. Rev. Lett. 57, 1696 (1986); J. C. Bergquist et al., Phys. Rev. Lett. 57, 1699 (1986).
[2] Z. K. Minev, S. O. Mundhada, S. Shankar, P. Rheinhold, R. Gutiérrez-Jáuregui, R. J. Schoelkopf, M. Mirrahimi, H. J. Carmichael, and M. H. Devoret, “To catch and reverse a quantum jump mid-flight,”  Nature 570, 200 (2019).

https://www.quantamagazine.org/quantum-leaps-long-assumed-to-be-instanta...

https://physicsworld.com/a/to-catch-a-quantum-jump/

https://www.quantamagazine.org/how-quantum-trajectory-theory-lets-physic...