Performance advantage in quantum simulation

Geometrically frustrated lattice and escape from topological obstructions.

D-Wave Systems has published a milestone study in collaboration with scientists at Google, demonstrating a computational performance advantage, increasing with both simulation size and problem hardness, to over 3 million times that of corresponding classical methods.

D-Wave researchers programmed the D-Wave 2000Q system to model a two-dimensional frustrated quantum magnet using artificial spins.

One important task is the simulation of geometrically frustrated magnets in which topological phenomena can emerge from competition between quantum and thermal fluctuations. The team reported on experimental observations of equilibration in such simulations, measured on up to 1440 qubits with microsecond resolution. By initializing the system in a state with topological obstruction, they observed Quantum Annealing (QA) equilibration timescales in excess of one microsecond. Measurements indicated a dynamical advantage in the quantum simulation compared with spatially local update dynamics of Path-Integral Monte Carlo (PIMC).

PIMC is a leading classical method for such simulations, and a scaling advantage of this type was recently shown to be impossible in certain restricted settings.  Notably, this work was achieved on a practical application with real-world implications. This performance advantage, exhibited in a complex quantum simulation of materials, is a meaningful step in the journey toward applications advantage in Quantum Computing.

This work also demonstrates that quantum effects can be harnessed to provide a computational advantage in D-Wave processors, at problem scale that requires thousands of qubits. This is therefore an important piece of experimental evidence that PIMC does not simulate QA dynamics even for sign-problem-free Hamiltonians, and that near-term quantum devices can be used to accelerate computational tasks of practical relevance.

The paper has been published in the journal Nature Communications

Read more.