NC State and Duke Quantum Computing Seminar

NC State & Duke will host a Collaborative Quantum Computing Seminar Sept 10, 2021!

Talk Title:  Gate-free state preparation for fast VQE molecular simulations

Speaker:  Oinam Romesh Meitei, Postdoctoral Associate, Massachusetts Institute of Technology

Abstract:  The variational quantum eigensolver (VQE) is currently the flagship algorithm for molecular simulations on near-term quantum computers. The algorithm involves implementing a sequence of parameterized gates on quantum hardware to generate a target quantum state and measuring the molecular energy. The number of gates that can be implemented on current quantum devices remains limited mainly due to finite coherence times and frequent gate errors, preventing accurate applications to systems with significant entanglement, such as strongly correlated molecules. In this work, we present an alternate approach (which we refer to as ctrl-VQE) where the quantum circuit used for state preparation is removed entirely and replaced by a quantum optimal control routine which variationally shapes a pulse to drive the initial Hartree-Fock state to the full CI target state. The objective function optimized is the ground state molecular energy. By removing the quantum circuit, the coherence times required for state preparation can be drastically reduced by directly optimizing the pulses at the device level. We demonstrate the potential of this method numerically by directly optimizing pulse shapes which accurately model the dissociation curves of H2 and HeH+, and the ground state energy for LiH. We further present an adaptive pulse shaping algorithm to avoid over-parameterization of pulse parameters.

This is a Hybrid Collaborative Event with NC State and Duke. The In Person location for NC State is Venture Place, 2nd Floor, Large Classroom.

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For more information email:

quantumcomputing@ncsu.edu