Weak distillation of quantum resources

TL;DR

This paper introduces a framework that enables weak simulation of quantum resources using quasi-probability decomposition, reducing sampling costs and extending the capabilities of error mitigation and resource distillation.

Contribution

It generalizes quasi-probability protocols from expectation estimation to weak simulation, significantly lowering sampling costs based on negativity.

Findings

Sampling cost is proportional to negativity of quasi-probability.

Method requires fewer samples in error mitigation and distillation scenarios.

Framework introduces a new notion of quantum resource distillation.

Abstract

Importance sampling based on quasi-probability decomposition is the backbone of many widely used techniques, such as error mitigation, circuit knitting, and, more generally, virtual quantum resource distillation, as it allows one to simulate operations that are not accessible in a given setting. However, this class of protocols faces a fundamental problem -- it only allows to estimate expectation values. Here, we provide a general framework that lifts any quasi-probability-based protocol from expectation value estimation to a weak simulator, realizing sampling from the desired distribution only using a restricted class of quantum resources. Our method runs with the sampling cost proportional to the negativity of the quasi-probability, in stark contrast to the naive estimation-based approach that requires a large number of samples even in the case of small negativity. We show that our method requires significantly fewer samples in a number of relevant scenarios, such as error mitigation, entanglement distillation and magic state distillation. Our framework realizes the weak simulation of quantum resources without actually distilling the state, introducing a new notion of quantum resource distillation.