Experimental Characterization, Modeling, and Analysis of Crosstalk in a Quantum Computer

Saki, Abdullah Ash; Alam, Mahabubul; Ghosh, Swaroop

doi:10.1109/tqe.2020.3023338

Cited by 37 publications

(19 citation statements)

References 23 publications

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“…COCOA can speed up the optimization by locally searching the optimal pulses based on certain prior knowledge. Using COCOA, we completely resolve the challenging problem, to implement either individually or simultaneously a single qubit X-gate in a strongly ZZ-interacting two-qubit system [12,13,69]. In conclusion, COCOA optimization is friendly to realistic quantum control tasks, easy to be customized, and easy to be extended to larger quantum systems.…”

Section: Discussionmentioning

confidence: 99%

“…Scalingup qubit systems tends to reduce the number of control degrees, which means taking out more control fields out of the system. Losing either the control of qubit frequencies or coupling strength brings more difficult in realizing good quantum gates, especially in the systems such as fixed frequency qubits with fixed couplings, tunable qubits with residual couplings, qubits with tunable couplings with unwanted interaction and crosstalk [68][69][70]. Fortunately, the degree of control freedom on the pulse-shaping could be further exploited with the help of COCOA.…”

Section: Applications On Superconducting Qubitsmentioning

confidence: 99%

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Optimizing quantum control pulses with complex constraints and few variables through Tensorflow

Song,

Li,

Hai

et al. 2021

Preprint

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Applying optimal control algorithms on realistic quantum systems confronts two key challenges: to efficiently adopt physical constraints in the optimization and to minimize the variables for the convenience of experimental tune-ups. In order to resolve these issues, we propose a novel algorithm by incorporating multiple constraints into the gradient optimization over piece-wise pulse constant values, which are transformed to contained numbers of the finite Fourier basis for bandwidth control. Such complex constraints and variable transformation involved in the optimization introduce extreme difficulty in calculating gradients. We resolve this issue efficiently utilizing autodifferentiation on Tensorflow. We test our algorithm by finding smooth control pulses to implement single-qubit and two-qubit gates for superconducting transmon qubits with always-on interaction, which remains a challenge of quantum control in various qubit systems. Our algorithm provides a promising optimal quantum control approach that is friendly to complex and optional physical constraints.

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Section: Discussionmentioning

confidence: 99%

Section: Applications On Superconducting Qubitsmentioning

confidence: 99%

Optimizing quantum control pulses with complex constraints and few variables through Tensorflow

Song,

Li,

Hai

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…One of the major challenges in current technology is understanding spatial correlations in noise. Whether or not noise is confined locally to a single qubit, or can be correlated across neighboring (or even distant) qubits (such as in crosstalk [39,40]) determines the efficacy of error mitigation techniques, and quantum error correction (where errors are typically assumed to be independent). Here we aim to find out, how well one can approximate non-local noise channels with the MATEN approach.…”

Section: Local Vs Non-local Channelsmentioning

confidence: 99%

“…For instance, with |S| = 16 we find the L2 distance goes as numshots −1. 39 . We note that the L2 distance between randomly chosen χ matrices was numerically found to be .800 ± .125, but we see fidelities much higher than this value for sufficiently large |S| and number of shots.…”

Section: Purely Local Noisementioning

confidence: 99%

Dual Map Framework for Noise Characterization of Quantum Computers

Sud,

Marshall,

Wang

et al. 2021

Preprint

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“…Recently, various studies on detection, characterization, and mitigation of crosstalk have been published [8,18,19,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. From a high-level and hardware-agnostic perspective, several schemes have been proposed for detecting and characterizing crosstalk in multi-qubit systems [19,[21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Quantum crosstalk analysis for simultaneous gate operations on superconducting qubits

Zhao¹,

Linghu²,

Li³

et al. 2021

Preprint

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Maintaining or even improving gate performance with growing numbers of parallel controlled qubits is a vital requirement towards fault-tolerant quantum computing. For superconducting quantum processors, though isolated one-or two-qubit gates have been demonstrated with high-fidelity, implementing these gates in parallel commonly show worse performance. Generally, this degradation is attributed to various crosstalks between qubits, such as quantum crosstalk due to residual inter-qubit coupling. An understanding of the exact nature of these crosstalks is critical to figuring out respective mitigation schemes and improved qubit architecture designs with low crosstalk. Here we give a theoretical analysis of quantum crosstalk impact on simultaneous gate operations in a qubit architecture, where fixed-frequency transmon qubits are coupled via a tunable bus, and sub-100-ns controlled-Z (CZ) gates can be realized by applying a baseband flux pulse on the bus. Our analysis shows that for microwave-driven single qubit gates, the dressing from qubit-qubit coupling can cause nonnegligible cross-driving errors when qubits operate near frequency collision regions. During CZ gate operations, although unwanted near-neighbor interactions are nominally turned off, sub-MHz parasitic next-near-neighbor interactions involving spectator qubits can still exist, causing considerable leakage or control error when one operates qubit systems around these parasitic resonance points. To ensure high-fidelity simultaneous operations, this could rise a request to figure out a better way to balance the gate error from target qubit systems themselves and the error from non-participating spectator qubits. Overall, our analysis suggests that towards useful quantum processors, the qubit architecture should be examined carefully in the context of high-fidelity simultaneous gate operations in a scalable qubit lattice.

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Experimental Characterization, Modeling, and Analysis of Crosstalk in a Quantum Computer

Cited by 37 publications

References 23 publications

Optimizing quantum control pulses with complex constraints and few variables through Tensorflow

Optimizing quantum control pulses with complex constraints and few variables through Tensorflow

Dual Map Framework for Noise Characterization of Quantum Computers

Quantum crosstalk analysis for simultaneous gate operations on superconducting qubits

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