Theoretical and Experimental Perspectives of Quantum Verification

Carrasco, José A.; Elben, Andreas; Kokail, Christian; Kraus, Barbara; Zoller, P.

doi:10.1103/prxquantum.2.010102

Cited by 78 publications

(50 citation statements)

References 72 publications

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“…The energy can be represented using a special type of matrix called Hamiltonian matrix. [2] To simulate a chemical molecule, the molecule is first described in terms of Hamiltonian matrix, then the operators are constructed. With these operators we can simulate the Hamiltonians in our quantum device.…”

Section: Quantum Algorithmsmentioning

confidence: 99%

Simulation and validation of qubits based on Phase estimation algorithm

Elanchezhiyan¹,

Tomar²

2022

IJSRP

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After the advent of Quantum Physics, new opportunities were created for research and development in the world of science and technology. Quantum computation is one such emerging technology which allows for notable speed-ups compared to conventional computational methods. Here a quantum bit simulator is presented. This simulator is an engineering work, and no deep understanding of quantum mechanics is required from the user. The well-known phase estimation algorithm is presented using this simulator. The qubit simulator will be a useful tool for the study of quantum computer circuits, quantum computing, and the development of new quantum algorithms

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Section: Quantum Algorithmsmentioning

confidence: 99%

Simulation and validation of qubits based on Phase estimation algorithm

Elanchezhiyan¹,

Tomar²

2022

IJSRP

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“…Subsequent certification that an actual physical system is performing as expected represents a leading concern for validating experimental results [ 13 ]. This is made more difficult by the inherent randomness that often manifests in the computed results, inability to pin-point exactly where in a circuit an error has occurred, curse of dimensionality, and the inability to step through program execution [ 14 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

Characterizing the Reproducibility of Noisy Quantum Circuits

Dasgupta

Humble

2022

Entropy

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The ability of a quantum computer to reproduce or replicate the results of a quantum circuit is a key concern for verifying and validating applications of quantum computing. Statistical variations in circuit outcomes that arise from ill-characterized fluctuations in device noise may lead to computational errors and irreproducible results. While device characterization offers a direct assessment of noise, an outstanding concern is how such metrics bound the reproducibility of a given quantum circuit. Here, we first directly assess the reproducibility of a noisy quantum circuit, in terms of the Hellinger distance between the computational results, and then we show that device characterization offers an analytic bound on the observed variability. We validate the method using an ensemble of single qubit test circuits, executed on a superconducting transmon processor with well-characterized readout and gate error rates. The resulting description for circuit reproducibility, in terms of a composite device parameter, is confirmed to define an upper bound on the observed Hellinger distance, across the variable test circuits. This predictive correlation between circuit outcomes and device characterization offers an efficient method for assessing the reproducibility of noisy quantum circuits.

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“…In contrast, swap gates provide highly nonlinear interactions and, although challenging, are available in a broad range of experimental platforms [32][33][34][35][36] and are thus ideally suited for nonlinear interferometry. The controlled-swap gate is a particularly attractive gate as it is an essential ingredient of swap tests which are useful for measuring properties of quantum states without full tomography [37], in particular state overlap and purity [38,39], and other verification tasks [40]. In addition, swap tests conditionally project the input states onto their symmetric or antisymmetric component, allowing the preparation of NOON states (|n |0 ±|0 |n )/ √ 2 from input Fock states |n , |0 and of entangled coherent states (|α 1 |α 2 ± |α 2 |α 1 )/ N ± from coherent states |α 1,2 .…”

mentioning

confidence: 99%

Swap-test interferometry with biased ancilla noise

Černotík¹,

Pietikäinen²,

Puri³

et al. 2021

Preprint

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The Mach-Zehnder interferometer is a powerful device for detecting small phase shifts between two light beams. Simple input states-such as coherent states or single photons-can reach the standard quantum limit of phase estimation while more complicated states can be used to reach Heisenberg scaling; the latter, however, require complex states at the input of the interferometer which are difficult to prepare. The quest for highly sensitive phase estimation therefore calls for interferometers with nonlinear devices which would make the preparation of these complex states more efficient.Here, we show that the Heisenberg scaling can be recovered with simple input states (including Fock and coherent states) when the linear mirrors in the interferometer are replaced with controlled-swap gates and measurements on ancilla qubits. These swap tests project the input Fock and coherent states onto NOON and entangled coherent states, respectively, leading to improved sensitivity to small phase shifts in one of the interferometer arms. We perform detailed analysis of ancilla errors, showing that biasing the ancilla towards phase flips offers a great advantage, and perform thorough numerical simulations of a possible implementation in circuit quantum electrodynamics. Our results thus present a viable approach to phase estimation approaching Heisenberg-limited sensitivity.

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Theoretical and Experimental Perspectives of Quantum Verification

Cited by 78 publications

References 72 publications

Simulation and validation of qubits based on Phase estimation algorithm

Simulation and validation of qubits based on Phase estimation algorithm

Characterizing the Reproducibility of Noisy Quantum Circuits

Swap-test interferometry with biased ancilla noise

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