Experimental implementation of non-Clifford interleaved randomized benchmarking with a controlled-S gate
Shelly Garion, Naoki Kanazawa, Haggai Landa, David C. McKay, Sarah Sheldon, Andrew W. Cross, Christopher J. Wood
备注：
9 pages, 4 figures, references are updated, QPT curve in the Fig. 2 is updated based on new analysis procedure detailed in Appendix B. Conclusions unchanged
Hardware efficient transpilation of quantum circuits to a quantum devices native gateset is essential for the execution of quantum algorithms on noisy quantum computers. Typical quantum devices utilize a gateset with a single two-qubit Clifford entangling gate per pair of coupled qubits, however, in some applications access to a non-Clifford two-qubit gate can result in more optimal circuit decompositions and also allows more flexibility in optimizing over noise. We demonstrate calibration of a low error non-Clifford Controlled-$\fracπ{2}$ phase (CS) gate on a cloud based IBM Quantum computing using the Qiskit Pulse framework. To measure the gate error of the calibrated CS gate we perform non-Clifford CNOT-Dihedral interleaved randomized benchmarking. We are able to obtain a gate error of $5.9(7) \times 10^{-3}$ at a gate length 263 ns, which is close to the coherence limit of the associated qubits, and lower error than the backends standard calibrated CNOT gate.
We introduce a scheme to characterise a qudit T gate that has different noise than a set of Clifford gates. We developed our scheme through representation theory and ring theory to generalise non-Clifford interleaved benchmarking to qudit systems. By restricting to the qubit case, we recover the dihedral benchmarking scheme. Our characterisation scheme provides experimental physicists a practical method for characterising universal qudit gate sets and advances randomised benchmarking research by providing the characterisation of a complete qudit library.
Phase-Altered Interleaved Randomized Benchmarking for Compiled Non-Clifford Gates
Center for Quantum Technologies, Department of Physics, Sofia University（索非亚大学物理系量子技术中心）；Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences（保加利亚科学院格奥尔基·纳贾科夫固体物理研究所）
Interleaved Benchmarking with Single-Qubit References
National University of Science and Technology “MISIS”（国立科技大学 MISIS）；Russian Quantum Center（俄罗斯量子中心）；Moscow Institute of Physics and Technology（莫斯科物理技术学院）；Institute of Nanotechnology of Microelectronics, Russian Academy of Sciences（俄罗斯科学院微电子纳米技术研究所）
Easier randomizing gates provide more accurate fidelity estimation
University of Waterloo（滑铁卢大学）；Institute for Quantum Computing, University of Waterloo（滑铁卢大学量子计算研究所）；Photonic Inc.（光子公司）；Keysight Technologies Canada（是德科技加拿大公司）；Department of Physics, University of California at Berkeley（加州大学伯克利分校物理系）；Applied Math and Computational Research Division, Lawrence Berkeley National Lab（劳伦斯伯克利国家实验室应用数学与计算研究部）；Quantinuum；Keysight Technologies Canada Inc.（是德科技加拿大公司）
Quantum computers have the potential to outperform classical computers in a range of computational tasks, such as prime factorisation and unstructured searching. However, real-world quantum computers are subject to noise. Quantifying noise is of vital importance, since it is often the dominant factor preventing the successful realisation of advanced quantum computations. Here we propose and demonstrate an interleaved randomised benchmarking protocol for measurement-based quantum computers that can be used to estimate the fidelity of any single-qubit measurement-based gate. We tested the protoc…
Non-Clifford Benchmarking via Ensemble Feature Selection
St Kliment Ohridski University of Sofia（圣克利门特·奥赫里德斯基索菲亚大学）；Center for Quantum Technologies, St Kliment Ohridski University of Sofia（圣克利门特·奥赫里德斯基索菲亚大学量子技术中心）
Variational quantum algorithms are considered to be appealing applications of near-term quantum computers. However, it has been unclear whether they can outperform classical algorithms or not. To reveal their limitations, we must seek a technique to benchmark them on large scale problems. Here, we propose a perturbative approach for efficient benchmarking of variational quantum algorithms. The proposed technique performs perturbative expansion of a circuit consisting of Clifford and Pauli rotation gates, which is enabled by exploiting the classical simulatability of Clifford circuits. Our meth…
Recently, there has been an emergence of useful applications for noisy intermediate-scale quantum (NISQ) devices notably, though not exclusively, in the fields of quantum machine learning and variational quantum algorithms. In such applications, circuits of various depths and composed of different sets of gates are run on NISQ devices. Therefore, it is crucial to find practical ways to capture the general performance of circuits on these devices. Motivated by this pressing need, we modified the standard Clifford randomized benchmarking (RB) and interleaved RB schemes targeting them to hardware…
In-situ benchmarking of fault-tolerant quantum circuits. I. Clifford circuits
Joint Center for Quantum Information and Computer Science, NIST/University of Maryland（量子信息与计算机联合中心，美国国家标准与技术研究院/马里兰大学）；Simons Institute for the Theory of Computing, University of California at Berkeley（西蒙斯计算理论研究所，加州大学伯克利分校）；Institute for Theoretical Physics, ETH Zürich（理论物理研究所，苏黎世联邦理工学院）；Department of Physics, Harvard University（物理学系，哈佛大学）；National Institute of Standards and Technology（美国国家标准与技术研究院）
With the development of controllable quantum systems, fast and practical characterization for multi-qubit gates is essential for building high-fidelity quantum computing devices. The usual way to fulfill this requirement via randomized benchmarking asks for the complicated implementation of numerous multi-qubit twirling gates. How to efficiently and reliably estimate the fidelity of a quantum process remains an open problem. In this work, we propose a character-cycle benchmarking protocol and a character-average benchmarking protocol only using local twirling gates to estimate the process fide…
Characterization of Unlearnable Noise with Mid-Circuit-Measurement-Based Cycle Benchmarking
Imperial College London（帝国理工学院）；Fraunhofer Institute for Industrial Mathematics（弗劳恩霍夫工业数学研究所）；Algorithmiq Ltd（Algorithmiq有限公司）；University of Helsinki（赫尔辛基大学）；Fraunhofer Center for Maritime Logistics（弗劳恩霍夫海事物流中心）
Randomized benchmarking (RB) is a powerful method for determining the error rate of experimental quantum gates. Traditional RB, however, is restricted to gatesets, such as the Clifford group, that form a unitary 2-design. The recently introduced character RB can benchmark more general gates using techniques from representation theory; up to now, however, this method has only been applied to "multiplicity-free" groups, a mathematical restriction on these groups. In this paper, we extend the original character RB derivation to explicitly treat non-multiplicity-free groups, and derive several app…
We characterize control of a qutrit implemented in the lowest three energy levels of a capacitively-shunted flux-biased superconducting circuit. Randomized benchmarking over the qutrit Clifford group yields an average fidelity of 98.89 $\pm$ 0.05%. For a selected subset of the Clifford group, we perform quantum process tomography and observe the behaviour of repeated gate sequences. Each qutrit gate is generated using only two-state rotations via a method applicable to any unitary. We find that errors are due to decoherence primarily and have a significant contribution from level shifts. This …
One of the main challenges in building a quantum processor is to characterize the environmental noise. Noise characterization can be achieved by exploiting different techniques, such as randomization where several sequences of random quantum gates are applied to the qubit under test to derive statistical characteristics about the affecting noises. A scalable and robust algorithm able to benchmark the full set of Clifford gates using randomization techniques is called randomized benchmarking. In this study, we simulated randomized benchmarking protocols in a semiconducting all-electrical three-…
Recent work has demonstrated that high-threshold quantum error correction is possible for biased-noise qubits, provided one can implement a controlled-not (CX) gate that preserves the bias. Bias-preserving CX gates have been proposed for several biased-noise qubit platforms, most notably Kerr cats. However, experimentally measuring the noise bias is challenging as it requires accurately estimating certain low-probability Pauli errors in the presence of much larger state preparation and measurement (SPAM) errors. In this paper, we introduce bias randomized benchmarking (BRB) as a technique for …
我们对随机基准（RB）的两个重要标准之间的差异进行了全面分析：最初在Emerson et al（2005）和Dankert et al（2006）中提出的Clifford组RB协议，以及后来由NIST组在Knill et al，PRA（2008）中提出的RB协议的变体。虽然这两个协议经常合并或假定等效，我们证明，它们产生不同的指数保真度衰减导致的差异高达3的因素，在实验现实条件下的估计错误率。出现这些差异是因为NIST RB协议不满足Clifford群协议中旋转的酉双设计条件，因此衰减率取决于误差模型的非不变特征。我们的分析提供了一个重要的第一步，制定明确的标准基准量子门和更严格的理论基础NIST协议和其他RB协议缺乏组结构。最后，我们讨论这些差异估计容错开销的潜在影响。
The increasing scale of near-term quantum hardware motivates the need for efficient noise characterization methods, since qubit and gate level techniques cannot capture crosstalk and correlated noise in many qubit systems. While scalable approaches, such as cycle benchmarking, are known for special classes of quantum circuits, the characterization of noise in general circuits with non-Clifford gates has been an unreachable task. We develop an algorithm that can sample-efficiently estimate the total amount of noise induced by a layer of arbitrary non-Clifford gates, including all crosstalks, an…
Randomized benchmarking (RB) is the gold standard for experimentally evaluating the quality of quantum operations. The current framework for RB is centered on groups and their representations, but this can be problematic. For example, Clifford circuits need up to $O(n^2)$ gates, and thus Clifford RB cannot scale to larger devices. Attempts to remedy this include new schemes such as linear cross-entropy benchmarking (XEB), cycle benchmarking, and non-uniform RB, but they do not fall within the group-based RB framework. In this work, we formulate the \emph{universal randomized benchmarking (URB)…
Randomized benchmarking (RB) is a widely used method for estimating the average fidelity of gates implemented on a quantum computing device. The stochastic error of the average gate fidelity estimated by RB depends on the sampling strategy (i.e., how to sample sequences to be run in the protocol). The sampling strategy is determined by a set of configurable parameters (an RB configuration) that includes Clifford lengths (a list of the number of independent Clifford gates in a sequence) and the number of sequences for each Clifford length. The RB configuration is often chosen heuristically and …
Efficient fidelity simulation of high-rate magic distillation circuits
QuEra Computing Inc.（QuEra 计算公司）；Joint Center for Quantum Information and Computer Science, University of Maryland（马里兰大学量子信息与计算机科学联合中心）；Simons Institute for the Theory of Computing, University of California at Berkeley（加州大学伯克利分校西蒙斯计算理论研究所）；Institute for Theoretical Physics, ETH Zürich（苏黎世联邦理工学院理论物理研究所）；Department of Physics, Harvard University（哈佛大学物理学系）
We construct a gate and time-independent noise model that results in the output of a logical randomized benchmarking protocol oscillating rather than decaying exponentially. To illustrate our idea, we first construct an example in standard randomized benchmarking where we assume the existence of ``hidden'' qubits, permitting a choice of representation of the Clifford group that contains multiplicities. We use the multiplicities to, with each gate application, update a hidden memory of the gate history that we use to circumvent theorems which guarantee the output decays exponentially. In our fo…
The performance of quantum gates is often assessed using some form of randomized benchmarking. However, the existing methods become infeasible for more than approximately five qubits. Here we show how to use a simple and customizable class of circuits -- randomized mirror circuits -- to perform scalable, robust, and flexible randomized benchmarking of Clifford gates. We show that this technique approximately estimates the infidelity of an average many-qubit logic layer, and we use simulations of up to 225 qubits with physically realistic error rates in the range 0.1-1% to demonstrate its scala…
