In a step toward practical quantum computing, researchers from MIT, Zapata Computing and Google have designed a system that can verify when quantum chips have accurately performed complex computations that classical computers can’t.
Noisy Intermediate Scale Quantum (NISQ) qubits computers can yet solve certain algorithms that are intractable for classical computers. Verifying that the chips performed operations as expected, however, can be very inefficient. The chip’s outputs can look entirely random, so it takes a long time to simulate steps to determine if everything went according to plan.
The team has described a novel protocol, called Variational Quantum Unsampling (VQU), to efficiently verify that an NISQ chip has performed all the right quantum operations. The protocol makes inspiration from neural networks and is based on a Quantum Neural Network (QNN).
They validated their protocol on a notoriously difficult quantum problem, the famous boson sampling, running on custom quantum photonic chip. (MIT)