# Fidelity Estimation

## Functionality Description

Fidelity Estimation is the certification technique which provides an estimate of the fidelity between the desired quantum process or state and the actual result obtained in the laboratory. Fidelity is a measure of the "closeness" of two quantum states. It expresses the probability that one state will pass a test to identify as the other. Hence this technique is used to certify if an experimental device prepares the desired quantum state. The figure of merit in these protocols is the fidelity of the prepared quantum state

## Protocols

## Properties

- This method is insensitive to the SPAM errors
- The figure of merit is fidelity of the prepared quantum state to the actual state
- This method is a certification technique which has lower sample and resource complexity than Tomography but a higher complexity than Randomised Benchmarking

## Related Papers

- S.Flammia et al (2011) arXiv:1104.4695v3: Direct Fidelity Estimation from Few Pauli Measurements

**contributed by Rhea Parekh*