Realizing symmetry-protected topological phases in a spin-1/2 chain with next-nearest-neighbor hopping on superconducting qubits

Tan, Adrian T. K.; Sun, Shi-Ning; Tazhigulov, Ruslan N.; Chan, Garnet Kin‐Lic; Minnich, Austin J.

doi:10.1103/physreva.107.032614

Cited by 9 publications

(1 citation statement)

References 94 publications

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“…As a type of Valence-Bond-Solid (VBS) state [37], it is the exact ground state of the spin-1 AKLT model, which is the paradigm of a strongly correlated symmetry protected topological (SPT) phase with a Haldane gap [38] and fractional excitations at its boundaries [36,39,40]. SPT phases of matter received much attention recently on quantum computers [17,[41][42][43][44][45][46], and the two-dimensional generalization of the AKLT model on a trivalent lattice is proposed to be a universal resource [47,48] for measurement-based quantum computation [49][50][51]. So far, the 1D AKLT state has been experimentally realized and characterized on photonic implementations [52] using cluster states [53] and in trapped ions [54].…”

Section: Introductionmentioning

confidence: 99%

High-fidelity realization of the AKLT state on a NISQ-era quantum processor

Chen,

Shen,

Lee

et al. 2023

SciPost Phys.

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The AKLT state is the ground state of an isotropic quantum Heisenberg spin-1 model. It exhibits an excitation gap and an exponentially decaying correlation function, with fractionalized excitations at its boundaries. So far, the one-dimensional AKLT model has only been experimentally realized with trapped-ions as well as photonic systems. In this work, we successfully prepared the AKLT state on a noisy intermediate-scale quantum (NISQ) era quantum device. In particular, we developed a non-deterministic algorithm on the IBM quantum processor, where the non-unitary operator necessary for the AKLT state preparation is embedded in a unitary operator with an additional ancilla qubit for each pair of auxiliary spin-1/2’s. Such a unitary operator is effectively represented by a parametrized circuit composed of single-qubit and nearest-neighbor CX gates. Compared with the conventional operator decomposition method from Qiskit, our approach results in a much shallower circuit depth with only nearest-neighbor gates, while maintaining a fidelity in excess of 99.99% with the original operator. By simultaneously post-selecting each ancilla qubit such that it belongs to the subspace of spin-up |↑>, an AKLT state can be systematically obtained by evolving from an initial trivial product state of singlets plus ancilla qubits in spin-up on a quantum computer, and it is subsequently recorded by performing measurements on all the other physical qubits. We show how the accuracy of our implementation can be further improved on the IBM quantum processor with readout error mitigation.

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Section: Introductionmentioning

confidence: 99%

High-fidelity realization of the AKLT state on a NISQ-era quantum processor

Chen,

Shen,

Lee

et al. 2023

SciPost Phys.

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Quantum computation of frequency-domain molecular response properties using a three-qubit iToffoli gate

Sun,

Marinelli,

Koh

et al. 2024

npj Quantum Inf

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The quantum computation of molecular response properties on near-term quantum hardware is a topic of substantial interest. Computing these properties directly in the frequency domain is desirable, but the circuits require large depth if the typical hardware gate set consisting of single- and two-qubit gates is used. While high-fidelity multipartite gates have been reported recently, their integration into quantum simulation and the demonstration of improved accuracy of the observable properties remains to be shown. Here, we report the application of a high-fidelity multipartite gate, the iToffoli gate, to the computation of frequency-domain response properties of diatomic molecules. The iToffoli gate enables a ~50% reduction in circuit depth and ~40% reduction in circuit execution time compared to the traditional gate set. We show that the molecular properties obtained with the iToffoli gate exhibit comparable or better agreement with theory than those obtained with the native CZ gates. Our work is among the first demonstrations of the practical usage of a native multi-qubit gate in quantum simulation, with diverse potential applications to near-term quantum computation.

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