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SUMMARY:QSE Quantum Seminar: "Utilizing and controlling collective states 
 in superconducting waveguide QED"
DTSTART:20260729T120000
DTEND:20260729T133000
DTSTAMP:20260916T044225Z
UID:7e48e6c263770454eb11981c473959ca90721c720928a473cc55876d
CATEGORIES:Conferences - Seminars
DESCRIPTION:Gerhard Kirchmair\nPlease join us for the QSE Center Quantu
 m Seminar with Gerhard Kirchmair from the Institute for Experimental Ph
 ysics\, University of Innsbruck and Institute for Quantum Optics and Quant
 um Information\, Austrian Academy of Sciences who will give a talk about 
 "Utilizing and controlling collective states in superconducting waveguide 
 QED" on Wednesday July 29th from 12:00 to 13:30.\nLocation: \n\nPizzas w
 ill be available at 12:00. All PhDs\, postdocs\, students\, group leaders
 \, and PIs are welcome to join us.\n\nTITLE: "Utilizing and controlling c
 ollective states in superconducting waveguide QED"\n\nABSTRACT: \nPropaga
 ting microwave photons in waveguides couple well to superconducting qubits
  and mediate long-range interactions between distant qubits causing the e
 mergence of collective states. Of particular interest are dark or subradi
 ant states\, which are protected from decoherence as they decouple from th
 e \nwaveguide environment. I will show how we can use collective states o
 f two qubits in the waveguide to build a primary thermometer which can di
 stinguish the influence of a local bath from the temperature of the mode 
 it should measure [1].Controlling individual qubits in waveguide QED syste
 m poses a challenge if one does not have access to individual addressing 
 ports. I show that with the use of dispersion we can achieve spatial addr
 essing of superconducting qubits separated by a subwavelength distance wit
 hin a microwave waveguide. This approach relies on a self-focusing effect
  to create a position-dependent interaction between a chirped pulse and a
 n individual qubit [2].Furthermore\, I will show the progress in building 
 and controlling a setup where we extend the system to larger arrays of tr
 ansmon qubits in a planar implementation. The goal is to have 8 Transmon 
 qubits\, coupled to a coplanar waveguide. The qubits will be spaced out by
  a distance that corresponds to half of the emission wavelength. In such 
 a system it will be possible to create subradiant states with up to four 
 excitations in different configurations [3\,4].\n[1] Sharafiev et.al. Phys
 . Rev. Lett. 134\, 213602 (2025)\n[2] Zanner et.al. Phys. Rev. Applied 24\
 , 014051 (2025)\n[3] Sheremet et.al. Rev. Mod. Phys. 95\, 015002 (2023)\n[
 4] Holzinger et.al.\, Phys. Rev. Let. 129\, 253601 (2022)\n\nBIO:\nGerhard
  Kirchmair was born in 1981 in Hall i.T.\, Austria. He studied physics at 
 the University of Innsbruck and did his diploma thesis in the group of Pro
 f. Rainer Blatt\, on building a laser for precision spectroscopy on Calciu
 m ions. For his PhD work\, he continued in the group of Prof. Blatt\, work
 ing on realizing quantum information protocols and quantum simulation expe
 riments with calcium ions in a linear Paul trap. He received his PhD in 20
 10\, with Presidential Honors\, on the subject “Quantum non-demolition m
 easurements and quantum simulation”. From 2010 on\, he joined the group 
 of Prof. Robert Schoelkopf as a post-doctoral associate at Yale University
 . There he was working on superconducting circuits coupled to Josephson ju
 nction qubits with a focus on implementing quantum optics experiments. He 
 contributed to developing the 3D circuit QED architecture which increased 
 coherence times of superconducting qubits by a factor of 100. He used this
  architecture to create setups for QIP and quantum optics experiments. The
 se experiments led to the observation of the single photon Kerr effect and
  the generation of microwave cat states consisting of more than 100 photon
 s. He is professor for experimental physics at the University of Innsbruck
  and Scientific Director at the Institute for Quantum Optics and Quantum I
 nformation of the Austrian Academy of Sciences. His research group works o
 n superconducting circuits for quantum optics and quantum simulation exper
 iments and on interfacing microwave circuits with micromechanical systems.
LOCATION:CE 1 103 https://plan.epfl.ch/?room==CE%201%20103
STATUS:CONFIRMED
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