Benchmarking and multi-qubit

System-level validation once individual gates are calibrated: randomized, purity and cross-entropy benchmarking, leakage-aware variants, and the multi-qubit signatures – GHZ parity, a Bell/CHSH correlation map, a process’s full Pauli transfer matrix, a repetition-code syndrome – that only show up once several qubits act together.

Randomized benchmarking of a two-qubit gate

Randomized benchmarking of a two-qubit gate

Single-qubit RB fidelity across the flux-tuning range

Single-qubit RB fidelity across the flux-tuning range

Simultaneous RB: crosstalk-limited fidelity vs spectator activity

Simultaneous RB: crosstalk-limited fidelity vs spectator activity

Purity RB: separating coherent from incoherent gate error

Purity RB: separating coherent from incoherent gate error

Cross-entropy benchmarking fidelity vs circuit depth and qubit count

Cross-entropy benchmarking fidelity vs circuit depth and qubit count

Leakage RB: population escaping the computational subspace

Leakage RB: population escaping the computational subspace

GHZ parity oscillation: N-fold fringes and their fading visibility

GHZ parity oscillation: N-fold fringes and their fading visibility

Quantum process tomography: the Pauli transfer matrix of a noisy gate

Quantum process tomography: the Pauli transfer matrix of a noisy gate

Repetition code: a space-time syndrome plot

Repetition code: a space-time syndrome plot

CHSH correlation map: where quantum mechanics beats any local theory

CHSH correlation map: where quantum mechanics beats any local theory