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SUMMARY:Zhicheng Zhang (University of Chinese Academy of Sciences\, Beijin
 g)
DTSTART:20210819T010000Z
DTEND:20210819T020000Z
DTSTAMP:20260423T010358Z
UID:UTSQSI/30
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/UTSQSI/30/">
 Parallel Quantum Algorithm for Hamiltonian Simulation</a>\nby Zhicheng Zha
 ng (University of Chinese Academy of Sciences\, Beijing) as part of Centre
  for Quantum Software and Information Seminar Series\n\n\nAbstract\nWe stu
 dy how parallelism can speed up quantum simulation. A parallel quantum alg
 orithm is proposed for simulating the dynamics of a large class of Hamilto
 nians with good sparse structures\, called uniform-structured Hamiltonians
 \, including various Hamiltonians of practical interest like local Hamilto
 nians and Pauli sums.\nGiven the oracle access to the target sparse Hamilt
 onian\, in both query and gate complexity\, the running time of our parall
 el quantum simulation algorithm measured by the quantum circuit depth has 
 a doubly (poly-)logarithmic dependence polylog log(1/є) on the simulation
  precision є. This presents an exponential improvement over the dependenc
 e polylog(1/є) of previous optimal sparse Hamiltonian simulation algorith
 m without parallelism. To obtain this result\, we introduce a novel notion
  of parallel quantum walk\, based on Childs’ quantum walk. The target ev
 olution unitary is approximated by a truncated Taylor series\, which is ob
 tained by combining these quantum walks in a parallel way. A lower bound 
 Ω(log log(1/є)) is established\, showing that the є-dependence of the 
 gate depth achieved in this work cannot be significantly improved.\nOur al
 gorithm is applied to simulating three physical models: the Heisenberg mod
 el\, the Sachdev-Ye-Kitaev model and a quantum chemistry model in second q
 uantization. By explicitly calculating the gate complexity for implementin
 g the oracles\, we show that on all these models\, the total gate depth of
  our algorithm has a polylog log(1/є) dependence in the parallel setting.
 \n\nOnline Seminar. To request the zoom link\, please send a message cqsia
 dmin@uts.edu.au using your business/organisation/institution email address
 . \nSeminar Webpage: https://www.uts.edu.au/research/centre-quantum-softwa
 re-and-information/events/qsi-seminar-zhicheng-zhang-ucas-beijing\n
LOCATION:https://researchseminars.org/talk/UTSQSI/30/
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