Direct Fidelity Estimation

Direct fidelity estimation (DFE) uses knowledge about the ideal target state or process to perform a tailored set of measurements to quickly certify a quantum state or a quantum process at lower cost than full tomography.

• Direct Fidelity Estimation
  • Simplistic state DFE example
  • Generalizing state DFE, somewhat
  • Process DFE
  • Process DFE by reduction to state DFE
  • Direct fidelity estimation in forest.benchmarking
  • Two quick examples
    • Step 1. Specify a state preparation or unitarty process with a Program
    • Step 2. Construct an ObservablesExperiment for DFE
    • Step 3. Acquire the data
    • Step 4. Apply some estimators to the data “do DFE”
    • Step 5. Visualize
  • State fidelity between \(\left|1\right\rangle\) and \(|\theta\rangle = R_y(\theta)\left|1\right\rangle\)
  • Process fidelity between \(I\) and \(R_y(\theta)\)
  • Advanced
    • Monte Carlo Sampling of large graph states
    • DFE measurements that include spectator qubits to signal cross talk.
    • Parallel state and process DFE

do_dfe(qc, benchmarker, program, qubits, …)

A wrapper around experiment generation, data acquisition, and estimation that runs a DFE experiment and returns the (fidelity, std_err) pair along with the experiment and results.

State DFE

generate_exhaustive_state_dfe_experiment(…)	Estimate state fidelity by exhaustive direct fidelity estimation.
generate_monte_carlo_state_dfe_experiment(…)	Estimate state fidelity by sampled direct fidelity estimation.

Process DFE

generate_exhaustive_process_dfe_experiment(…)	Estimate process fidelity by exhaustive direct fidelity estimation (DFE).
generate_monte_carlo_process_dfe_experiment(…)	Estimate process fidelity by randomly sampled direct fidelity estimation.

Data Acquisition

acquire_dfe_data(qc, expt, num_shots, …)

Acquire data necessary for direct fidelity estimate (DFE).

Analysis

estimate_dfe(results, kind)

Analyse data from experiments to obtain a direct fidelity estimate (DFE).