US 12,346,770 B2
Variational quantum state preparation
Ryan Babbush, Venice, CA (US); and Ian David Kivlichan, Cambridge, MA (US)
Assigned to Google LLC, Mountain View, CA (US)
Filed by Google LLC, Mountain View, CA (US)
Filed on May 2, 2024, as Appl. No. 18/653,705.
Application 18/653,705 is a continuation of application No. 16/967,339, granted, now 12,008,433, previously published as PCT/US2019/045412, filed on Aug. 7, 2019.
Claims priority of provisional application 62/715,615, filed on Aug. 7, 2018.
Prior Publication US 2024/0289659 A1, Aug. 29, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. G06N 10/20 (2022.01); G06F 15/16 (2006.01)
CPC G06N 10/20 (2022.01) [G06F 15/16 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A method performed by quantum computing hardware and one or more classical processors for preparing an eigenstate of a Hamiltonian, the method comprising:
evolving, by the quantum computing hardware, an initial quantum state of a system of physical qubits included in the quantum computing hardware according to a time evolution operator to generate an intermediate quantum state, wherein the time evolution operator comprises a truncation of the Hamiltonian, the evolving is performed for a truncated number of time steps, and the truncated number of time steps scales at a rate that is less than sub-logarithmic in a first predetermined error tolerance; and
variationally adjusting, by the quantum computing hardware and the one or more classical processors, the intermediate quantum state of the system of physical qubits to determine a wavefunction that approximates the eigenstate of the Hamiltonian and satisfies the first predetermined error tolerance.