Quantum process tomography via completely positive and trace-preserving projection

Knee, George C.; Bolduc, Eliot; Leach, Jonathan; Gauger, Erik M.

doi:10.1103/physreva.98.062336

Cited by 59 publications

(41 citation statements)

References 44 publications

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“…In typical cases, the resulting description of the unknown quantum process found by our ansatz is an order of magnitude more accurate than the naïve initial guess. In the future, we hope to improve the efficiency and accuracy of the classical algorithm underlying our reconstruction method [52,53].…”

Section: Discussionmentioning

confidence: 99%

“…The accuracy of the PAPA reconstructions for these simulated gates is set by the specifics of the classical numerical algorithm implemented (see Appendix D for details). If other algorithms [52,53] more tailored to quantum process reconstruction are used with PAPA we expect significant improvements in accuracy and runtime are possible.…”

Section: A Noisy One-and Two-qubit Gatesmentioning

confidence: 99%

“…For instance, we would aim to prevent the solver from getting stuck in regions where the gradient of the cost function is below the tolerance threshold, but the solution accuracy is not. One route forward would be to adapt to PAPA more sophisticated optimization algorithms tailored for optimization over positive definite matrices, such as those using gradient descent [52,53].…”

Section: Appendix D: Numerical Implementationmentioning

confidence: 99%

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Bootstrapping quantum process tomography via a perturbative ansatz

Govia¹,

Ribeill²,

Ristè³

et al. 2020

Nat Commun

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Quantum process tomography has become increasingly critical as the need grows for robust verification and validation of candidate quantum processors. Here, we present an approach for efficient quantum process tomography that uses a physically motivated ansatz for an unknown quantum process. Our ansatz bootstraps to an effective description for an unknown process on a multi-qubit processor from pairwise two-qubit tomographic data. Further, our approach can inherit insensitivity to system preparation and measurement error from the two-qubit tomography scheme. We benchmark our approach using numerical simulation of noisy three-qubit gates, and show that it produces highly accurate characterizations of quantum processes. Further, we demonstrate our approach experimentally, building three-qubit gate reconstructions from two-qubit tomographic data.

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Section: Discussionmentioning

confidence: 99%

Section: A Noisy One-and Two-qubit Gatesmentioning

confidence: 99%

Section: Appendix D: Numerical Implementationmentioning

confidence: 99%

See 1 more Smart Citation

Bootstrapping quantum process tomography via a perturbative ansatz

Govia¹,

Ribeill²,

Ristè³

et al. 2020

Nat Commun

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“…In order to obtain the projection, one can employ techniques proposed in Ref. [22]. In order to estimate an upper bound on the Hilbert-Schmidt distance ∆ HS (ρ E , ρ rec E ) we use the following inequality:…”

Section: Quantum Process Tomography With Guaranteed Precisionmentioning

confidence: 99%

Estimating the precision for quantum process tomography

2020

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Quantum tomography is a widely applicable tool for complete characterization of quantum states and processes. In the present work, we develop a method for precision-guaranteed quantum process tomography. With the use of the Choi-Jamiokowski isomorphism, we generalize the recently suggested extended norm minimization estimator for the case of quantum processes. Our estimator is based on the Hilbert-Schmidt distance for quantum processes. Specifically, we discuss the application of our method for characterizing quantum gates of a superconducting quantum processor in the framework of the IBM Q Experience.

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“…The Choi matrix, ρ E , is experimentally reconstructed using the maximum-likelihood estimation. Better algorithms have also been recently proposed for QPT [37]. Finally, the process matrix is directly obtained from the Choi matrix.…”

Section: Theory Of Quantum Process Tomographymentioning

confidence: 99%

Quantum process tomography of a high-dimensional quantum communication channel

Bouchard

Hufnagel

Koutný

et al. 2019

Quantum

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The characterization of quantum processes, e.g. communication channels, is an essential ingredient for establishing quantum information systems. For quantum key distribution protocols, the amount of overall noise in the channel determines the rate at which secret bits are distributed between authorized partners.In particular, tomographic protocols allow for the full reconstruction, and thus characterization, of the channel. Here, we perform quantum process tomography of high-dimensional quantum communication channels with dimensions ranging from 2 to 5. We can thus explicitly demonstrate the effect of an eavesdropper performing an optimal cloning attack or an interceptresend attack during a quantum cryptographic protocol. Moreover, our study shows that quantum process tomography enables a more detailed understanding of the channel conditions compared to a coarse-grained measure, such as quantum bit error rates. This full characterization technique allows us to optimize the performance of quantum key distribution under asymmetric experimental conditions, which is particularly useful when considering high-dimensional encoding schemes.

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Quantum process tomography via completely positive and trace-preserving projection

Cited by 59 publications

References 44 publications

Bootstrapping quantum process tomography via a perturbative ansatz

Bootstrapping quantum process tomography via a perturbative ansatz

Estimating the precision for quantum process tomography

Quantum process tomography of a high-dimensional quantum communication channel

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