search

quantumlib / Cirq

A Python framework for creating, editing, and invoking Noisy Intermediate Scale Quantum (NISQ) circuits.
Apache License 2.0
4.3k stars 1.02k forks source link

Add a simulator in the style of the paper `Classical algorithms for quantum mean values` #2638

Closed vtomole closed 4 years ago

vtomole commented 4 years ago

Calculating mean values is very NISQY. VQE, QAOA e.t.c: https://arxiv.org/abs/1909.11485

crystalzhaizhai commented 4 years ago

Could you please assign it to me?

kevinsung commented 4 years ago

These are classical algorithms; why do they belong in Cirq?

vtomole commented 4 years ago

These are classical algorithms in the sense that CHP (https://www.scottaaronson.com/chp/) is a classical algorithm that simulates certain types of quantum circuits efficiently on a classical computer. It's in the same vein as the clifford simulator. These algorithms calculate: Given a short depth circuit U and an observable O, calculate <0|U^+OU|0>. Some structures of this observable can be calculated efficiently with these algorithms (Positive semi definite, close to I, hermitian).