A17.00004. Variational Fast Forwarding for Quantum Simulation Beyond the Coherence Time

Presented by: Andrew Sornborger


Trotterization-based, iterative approaches to quantum simulation are restricted to simulation times less than the coherence time of the quantum computer, which limits their utility in the near term. Here, we present a hybrid quantum-classical algorithm, called Variational Fast Forwarding (VFF), for decreasing the quantum circuit depth of quantum simulations. VFF seeks an approximate diagonalization of a short-time simulation to enable longer-time simulations using a constant number of gates. Our error analysis provides two results: (1) the simulation error of VFF scales at worst linearly in the fast-forwarded simulation time, and (2) our cost function's operational meaning as an upper bound on average-case simulation error provides a natural termination condition for VFF. We implement VFF for the Hubbard, Ising, and Heisenberg models on a simulator. Finally, we implement VFF on Rigetti's quantum computer to show simulation beyond the coherence time. See full paper at: https://arxiv.org/abs/1910.04292 *Support: U.S. DOE Oppenheimer Fellowship, Off. of Science, Basic Energy Sci., Materials Sciences and Eng. Division, Condensed Matter Theory Program. DOE ASC Beyond Moore's Law program; LANL's LDRD program. EPSRC Natl'l Quantum Tech. Hub in Networked Quantum Information Technologies.


  • Andrew Sornborger
  • Cristina Cirstoiu
  • Zoe Holmes
  • Joseph Iosue
  • Lukasz Cincio
  • Patrick Coles


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