Qubit spin ice

King, Andrew D.; Nisoli, Cristiano; Dahl, Edward D.; Poulin-Lamarre, Gabriel; López-Bezanilla, Alejandro

doi:10.1126/science.abe2824

Cited by 55 publications

(40 citation statements)

References 37 publications

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“…These two approaches, shown in Fig. S2a, have become an important and standard ingredient of simulations of degenerate systems [7,8,34,37,38]. Here we give a more detailed description of these methods than in previous works.…”

Section: Calibration Refinement Shimmentioning

confidence: 99%

“…1 is based on qubit parameters extracted through averaged singlequbit measurements. Since qubits are actually multilevel objects rather than perfect two-level Ising spins, we convert the qubit Hamiltonian to an effective Ising Hamiltonian following the method laid out in recent studies of geometrically frustrated lattices [34,37]. We perform approximate diagonalization of the s-dependent eigenspectrum of a 12-qubit periodic chain Hamiltonian.…”

Section: Annealing Schedulementioning

confidence: 99%

“…The average and error bars representing 95% statistical confidence in TEBD data were obtained for 300 realizations of disorder. We follow the method used in recent experiments [34,37] to extract an effective transverse-field Ising Hamiltonian from a qubit model based on single-qubit measurements. The first task is to generate an eigenspectrum capturing the energy of fundamental local excitations.…”

Section: Fermionized Models and Tebdmentioning

confidence: 99%

See 2 more Smart Citations

Coherent quantum annealing in a programmable 2000-qubit Ising chain

King¹,

Suzuki²,

Raymond³

et al. 2022

Preprint

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Section: Calibration Refinement Shimmentioning

confidence: 99%

Section: Annealing Schedulementioning

confidence: 99%

Section: Fermionized Models and Tebdmentioning

confidence: 99%

See 1 more Smart Citation

Coherent quantum annealing in a programmable 2000-qubit Ising chain

King¹,

Suzuki²,

Raymond³

et al. 2022

Preprint

Self Cite

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“…Commercial devices developed by D-Wave Systems that realize programmable quantum annealing in hardware have now been available for more than a decade [9]. Not only can these devices be used to solve optimization problems by physically realizing quantum annealing, but they are also able to perform physics experiments, for example, spin-glass phase transitions [10], the Kosterlitz-Thouless phase transition [11,12], alternating-sector ferromagnetic chains [13], the Kibble-Zurek mechanism [14][15][16], the Griffiths-McCoy singularity [17], spin ice [18], the Shastry-Sutherland model [19], field theory [20], and spin liquids [21].…”

Section: Introductionmentioning

confidence: 99%

Breakdown of the weak coupling limit in quantum annealing

Bando,

Yip,

Chen

et al. 2021

Preprint

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Reverse annealing is a variant of quantum annealing, in which the system is prepared in a classical state, reverse-annealed to an inversion point, and then forward-annealed. We report on reverse annealing experiments using the D-Wave 2000Q device, with a focus on the p = 2 p-spin problem, which undergoes a second order quantum phase transition with a gap that closes polynomially in the number of spins. We concentrate on the total and partial success probabilities, the latter being the probabilities of finding each of two degenerate ground states of all spins up or all spins down, the former being their sum. The empirical partial success probabilities exhibit a strong asymmetry between the two degenerate ground states, depending on the initial state of the reverse anneal. To explain these results, we perform open-system simulations using master equations in the limits of weak and strong coupling to the bath. The former, known as the adiabatic master equation (AME), with decoherence in the instantaneous energy eigenbasis, predicts perfect symmetry between the two degenerate ground states, thus failing to agree with the experiment. In contrast, the latter, known as the polaron transformed Redfield equation (PTRE), is in close agreement with experiment. The same is true for a purely classical model known as spin-vector Monte Carlo with transverse-fielddependent updates (SVMC-TF). Thus our results present a strong challenge to the sufficiency of the weak system-bath coupling limit in describing the dynamics of current experimental quantum annealers, at least for annealing on timescales of a µsec or longer.

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“…However, the phase transition between them is still controversial [14,17]. Importantly, the planar pyrochlore lattice is recently experimentally realized in the Rydberg atoms array [18,19] and superconducting qubits systems [20,21]. Thus, as an experimentally achievable mixture of flat band physics and emergent low dimensional gauge field, the quantum many body physics in the planar pyrochlore lattice becomes more appealing.…”

mentioning

confidence: 99%

Dynamics in the planar pyrochlore lattice: bow-tie flat band and mixed 't Hooft anomaly

Xiong¹,

Xu²,

Zhang³

2021

Preprint

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The quantum phase transition between Z 2 plaquette valence bound solid (PVBS) and superfluid (SF) phases on the planar pyrochlore lattice (square ice) is under debate, because the conventional deconfined theory does not support continuous one, but the numerical evidence is still not solid. Here, we propose the system can be effectively described by a 2+1 dimensional Abelian-Higgs model which may host the mixed 't Hooft anomaly, so that the deconfinement can exist on the domain walls at the transition point. To verify it, we study the spin excitation spectra by combining stochastic analytic continuation and quantum Monte Carlo simulation. In both PVBS and SF phases, a flat band with bow-tie structure is observed and can be explained by group theoretic analysis. At the transition point, the spectra turn to be continuous and gapless, which indicates the topological excitations. From the snapshot of the spin configuration in real space, we found the existence of the domain wall in which the symmetries satisfy the anomaly. Meanwhile, a Luttinger liquid like continuum implies additional domain walls (point-defect) can emerge in the domain walls (line-defect) and take the role of deconfinement at transition point, as prediction of mixed 't Hooft anomaly. Our work can build a new bridge between the topological gauge field theory and a strongly correlated system.

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Qubit spin ice

Cited by 55 publications

References 37 publications

Coherent quantum annealing in a programmable 2000-qubit Ising chain

Coherent quantum annealing in a programmable 2000-qubit Ising chain

Breakdown of the weak coupling limit in quantum annealing

Dynamics in the planar pyrochlore lattice: bow-tie flat band and mixed 't Hooft anomaly

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