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SUMMARY:Photon-Instanton Collider Implemented by a Superconducting Circuit
 : Splitting a Single Photon - Moshe Goldstein (Tel Aviv University)
DTSTART:20220526T130000Z
DTEND:20220526T140000Z
UID:TALK168716@talks.cam.ac.uk
CONTACT:Jan Behrends
DESCRIPTION:How would our world look like if the fine structure constant 
 α were of order unity? While in our small α world an atom excited to the
  first excited state has negligible probability of decaying to the ground 
 state while emitting more than a single photon\, such processes are import
 ant in a large α world\, making photon frequency conversion effective in 
 the single-photon regime. We show how such behavior can be realized in a s
 uperconducting circuit QED system\, where a transmon\, which serves as an 
 artificial atom\, is galvanically coupled to a high-impedance Josephson ju
 nction array\, which acts as a waveguide for microwave photons with a high
  effective α. Instantons (phase slips) that occur in the transmon interac
 t with the microwave photons\, and lead to inelastic scattering probabilit
 ies which approach unity and greatly exceed the effect of the quartic anha
 rmoncity of the Josephson potential [1]. The instanton-photon cross sectio
 n is calculated using a novel formalism which allows to directly observe t
 he dynamical properties of the instantons\, and should be useful in other 
 quantum field theoretical contexts. The calculated inelastic decay rates c
 ompare well with recent measurements from the Manucharyan group at Marylan
 d [2]. I will also show how this effects can be used to shed a single-phot
 on light on the Bulgadaev-Schmid superconductor-to-insulator transition in
  the transmon\, which has been the center of a recent controversy.\n\n\nRe
 ferences:\n\n[1] Photon-instanton collider implemented by a superconductin
 g circuit\, A. Burshtein\, R. Kuzmin\, V. E. Manucharyan\, and M. Goldstei
 n\, Phys. Rev. Lett. 126 137701 (2021).\n\n[2] Photon decay in circuit qua
 ntum electrodynamics\, R. Kuzmin\, N. Grabon\, N. Mehta\, A. Burshtein\, M
 . Goldstein\, M. Houzet\, L. I. Glazman\, and V. E. Manucharyan\, Phys. Re
 v. Lett. 126\, 197701 (2021).
LOCATION:Details of video conferencing will be distributed nearer the time
 .
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