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SUMMARY:Hamiltonian dynamics simulation using linear combination of unitar
 ies on an ion trap quantum computer - Michelle W Sze\, Quantinuum
DTSTART:20250514T113000Z
DTEND:20250514T130000Z
UID:TALK230890@talks.cam.ac.uk
CONTACT:Chiara Leadbeater
DESCRIPTION:The linear combination of unitaries (LCU) method has proven to
  scale better than existing product formulas in simulating long time Hamil
 tonian dynamics. However\, given the number of multi-control gate operatio
 ns in the standard prepare-select-unprepare architecture of LCU\, it is st
 ill resource-intensive to implement on the current quantum computers. In t
 his seminar\, I will give a brief introductory course on LCU. I will then 
 demonstrate our LCU implementation on an ion trap quantum computer for cal
 culating squared overlaps |⟨ψ(t=0)|ψ(t>0)⟩|^2 of time-evolved states
 . Our method is based on pre-selecting relevant unitaries\, coupled with a
  compilation strategy which makes use of quantum multiplexor gates\, leadi
 ng to a significant reduction in the depth and number of two-qubit gates i
 n circuits. For L Pauli strings in a Taylor series expanded n-qubit-mapped
  time evolution operator\, we find a two-qubit gate count of 2⌈log2(L)
 ⌉(2n+1)−n−2. We test this approach by simulating a Rabi-Hubbard Hami
 ltonian.
LOCATION:Todd-Hamied Room\, Department of Chemistry\, Cambridge
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