18–23 Aug 2014
Nordita, Stockholm
Europe/Stockholm timezone

Quantum acoustics: Propagating phonons coupled to a superconducting qubit

22 Aug 2014, 09:00
45m
Oskar Klein-auditoriet (FR4) (Nordita, Stockholm)

Oskar Klein-auditoriet (FR4)

Nordita, Stockholm

Speaker

Prof. Per Delsing (Chalmers University of Technology, Sweden)

Description

Abstract: Mechanical movement can be quantized in the same way as light, into particles of vibration known as phonons. Recent experiments have shown that quantum information generated in qubits can be converted to vibrations in mechanical resonators, which resemble miniature drum skins or piano strings. Such resonators restrict motion to their discrete and stationary modes, and thus serve as local storage units for phonons. Here, we demonstrate the use of phonons as propagating carriers of quantum information, by coupling them strongly to a superconducting qubit. The phonons thus serve the same role as itinerant photons have in the field of quantum optics. Three different experiments are presented: i) Exciting the qubit with an electromagnetic signal we can “listen” to the SAW phonons emitted by the qubit. The low speed of sound also allows us to observe the emission of the qubit in the time domain, giving clear proof that the dominant coupling is acoustic. ii) Reflecting a SAW wave off the qubit, we observe a nonlinear reflection with strong reflection at low power and low reflection at high power. iii) Exciting the qubit with both an electromagnetic signal and with a SAW signal, we can do two tone spectroscopy on the qubit. Due to the low speed of sound and a potential for very strong coupling, the use of propagating phonons as quantum carriers allows regimes to be explored, which are difficult or impossible to reach with photons. This work was done in collaboration with M.V. Gustafsson, T. Aref, A. Frisk- Kockum, M.K. Ekström, and G. Johansson.

Presentation materials