Hamiltonian dynamics simulation using linear combination of unitaries on an ion trap quantum computer

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• Michelle W Sze, Quantinuum
• Wednesday 14 May 2025, 12:30-14:00
• Todd-Hamied Room, Department of Chemistry, Cambridge.

If you have a question about this talk, please contact Chiara Leadbeater.

The linear combination of unitaries (LCU) method has proven to scale better than existing product formulas in simulating long time Hamiltonian dynamics. However, given the number of multi-control gate operations in the standard prepare-select-unprepare architecture of LCU , it is still resource-intensive to implement on the current quantum computers. In this seminar, I will give a brief introductory course on LCU . I will then demonstrate our LCU implementation on an ion trap quantum computer for calculating 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, leading to a significant reduction in the depth and number of two-qubit gates in 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 Hamiltonian.

This talk is part of the Quantum Computing for Quantum Chemistry series.

This talk is included in these lists:

• Quantum Computing for Quantum Chemistry
• Todd-Hamied Room, Department of Chemistry, Cambridge

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