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SUMMARY:Symmetry-Protected Qubits and Non-Reciprocal Devices: Building Blo
 cks for Superconducting Quantum Hardware\, Dr. Chen-How Huang\, University
  of Jyväskylä
DTSTART:20260730T060000Z
DTEND:20260730T080000Z
DTSTAMP:20260816T101300Z
UID:indico-event-229@indico.phys.nthu.edu.tw
DESCRIPTION:Scalable quantum computing requires two distinct ingredients: 
 qubits that store informationrobustly\, and devices that route and control
  quantum signals between them. This seminarpresents two results\, one for 
 each ingredient\, unified by a common design principle: symmetryprotection
  can be engineered rather than merely observed. On the qubit side\, we pro
 pose aspin-singlet qubit realized in triangulene spin-1 chains coupled to 
 a superconducting substrate.Using the numerical renormalization group (NRG
 )\, we identify a pair of low-lying singlet states\,isolated from opposite
 -parity doublets by an avoided crossing\, that is intrinsically protecteda
 gainst random Zeeman and spin-orbit noise. On the device side\, we address
  non-reciprocalmulti-terminal microwave components such as circulators\, w
 hich are central to next-generationscalable circuit quantum electrodynamic
 s (cQED). The standard criterion\, that both time-reversaland spatial inve
 rsion must be broken\, states only whether non-reciprocity can exist. It d
 oes notpredict which of the many inequivalent multi-terminal responses are
  allowed\, nor how the devicegeometry selects among them. We close this ga
 p with a group-theoretical classification thatpartitions all possible resp
 onse configurations into symmetry orbits and yields explicit selectionrule
 s linking device geometry to admissible circulator-type responses\, valida
 ted on a minimalquantum-dot model. Together\, these results outline a rese
 arch programme in which symmetryprinciples guide the design of both the in
 formation-storage and the signal-routing components ofsuperconducting quan
 tum hardware for quantum computers.\n\nhttps://indico.phys.nthu.edu.tw/eve
 nt/229/
LOCATION:Physics/019 (NTHU)
URL:https://indico.phys.nthu.edu.tw/event/229/
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