Kenneth Rudinger

Demonstration of qubit operations below a rigorous fault tolerance threshold with gate set tomography

Quantum information processors promise fast algorithms for problems inaccessible to classical computers. But since qubits are noisy and error-prone, they will depend on fault-tolerant quantum error correction (FTQEC) to compute reliably. Quantum error correction can protect against general noise if—and only if—the error in each physical qubit operation is smaller than a certain threshold. The threshold for general errors is quantified by their diamond norm. Until now, qubits have been assessed primarily by randomized benchmarking, which reports a different error rate that is not sensitive to all errors, and cannot be compared directly to diamond norm thresholds. Here we use gate set tomography to completely characterize operations on a trapped-Yb+-ion qubit and demonstrate with greater than 95% confidence that they satisfy a rigorous threshold for FTQEC (diamond norm ≤6.7 × 10−4).

Optimization of a solid-state electron spin qubit using gate set tomography

State of the art qubit systems are reaching the gate fidelities required for scalable quantum computation architectures. Further improvements in the fidelity of quantum gates demands characterization and benchmarking protocols that are efficient, reliable and extremely accurate. Ideally, a benchmarking protocol should also provide information on how to rectify residual errors. Gate Set Tomography (GST) is one such protocol designed to give detailed characterization of as-built qubits. We implemented GST on a high-fidelity electron-spin qubit confined by a single

Noninteracting multiparticle quantum random walks applied to the graph isomorphism problem for strongly regular graphs

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What Randomized Benchmarking Actually Measures

P atom in

Comparing Algorithms for Graph Isomorphism Using Discrete- and Continuous-Time Quantum Random Walks

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Spectroscopic study of the cycling transition 4s[3/2]{sub 2}-4p[5/2]{sub 3} at 811.8 nm in {sup 39}Ar: Hyperfine structure and isotope shift

Si. The results reveal systematic errors that a randomized benchmarking analysis could measure but not identify, whereas GST indicated the need for improved calibration of the length of the control pulses. After introducing this modification, we measured a new benchmark average gate fidelity of

Experimental Demonstration of a Cheap and Accurate Phase Estimation

99.942(8)\%

Publisher Correction: Demonstration of qubit operations below a rigorous fault tolerance threshold with gate set tomography

, an improvement on the previous value of

Turbocharging Quantum Tomography

99.90(2)\%

Certifying qubit operations below the fault tolerance threshold

. Furthermore, GST revealed high levels of non-Markovian noise in the system, which will need to be understood and addressed when the qubit is used within a fault-tolerant quantum computation scheme.