Enhanced non-Markovian behavior in quantum walks with Markovian disorder

Kumar, N. Pradeep; Banerjee, Subhashish; Chandrashekar, C. M.

doi:10.1038/s41598-018-27132-7

Cited by 27 publications

(18 citation statements)

References 51 publications

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“…Similarly, contextdependent gates allow for poorly understood forms of dynamical errors not describable by a Markov model. This is one of the largest obstacles to near-term QIPs; non-Markovian noise must be either eliminated or, as some have suggested, harnessed into a resource [15][16][17][18][19] . Until recently, there has not been a clear operational definition for quantum non-Markovianity, nor consensus that one unifying measure could even be found.…”

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confidence: 99%

Demonstration of non-Markovian process characterisation and control on a quantum processor

et al. 2020

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In the scale-up of quantum computers, the framework underpinning fault-tolerance generally relies on the strong assumption that environmental noise affecting qubit logic is uncorrelated (Markovian). However, as physical devices progress well into the complex multi-qubit regime, attention is turning to understanding the appearance and mitigation of correlated — or non-Markovian — noise, which poses a serious challenge to the progression of quantum technology. This error type has previously remained elusive to characterisation techniques. Here, we develop a framework for characterising non-Markovian dynamics in quantum systems and experimentally test it on multi-qubit superconducting quantum devices. Where noisy processes cannot be accounted for using standard Markovian techniques, our reconstruction predicts the behaviour of the devices with an infidelity of 10−3. Our results show this characterisation technique leads to superior quantum control and extension of coherence time by effective decoupling from the non-Markovian environment. This framework, validated by our results, is applicable to any controlled quantum device and offers a significant step towards optimal device operation and noise reduction.

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confidence: 99%

Demonstration of non-Markovian process characterisation and control on a quantum processor

et al. 2020

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“…Such disruption from the homogeneity present in standard quantum walks could be detrimental for optimizing search algorithms. On the contrary, both of these disorders have been studied extensively in enhancing the entanglement and non-Markovianity generated between the internal and external degrees of freedom [30,31].…”

Section: B Disorder Inducing Quantum Walksmentioning

confidence: 99%

Characterization of anomalous diffusion in one-dimensional quantum walks

Hegde,

Chandrashekar

2021

Preprint

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Quantum walks are known to propagate quadratically faster than their classical counterparts and used to model dynamics in various quantum systems. The spread of the quantum walk in position space show anomalous diffusion behavior. By controlling the action of quantum coin operation on the corresponding coin degree of freedom of the walker, one can demonstrate control over the diffusion behavior. In this work, we report different forms of coin operations on quantum walks exhibiting anomalous diffusion behavior. Homogeneous and accelerated quantum walks display superdiffusive behavior, whereas uncorrelated static and dynamic disorders in the evolution induce strong and weak localization of the particle indicating subdiffusive and normal diffusive behavior. The role played by the interference effects in spreading of the walker has remained elusive and our aim in this work is to present the interplay between quantum coherence and mean squared displacement of the walker. We employ two reliable measures of coherence for conclusively establishing role of quantum interference as the driving force behind the anomalous diffusive behavior in the dynamics of quantum walks.

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“…Discrete-time quantum walks are great platforms for simulating the topological phases of matter [28,65,66], quantum quenches [29,30], and disorder phenomena [67][68][69]. Following Ref.…”

Section: Experimental Realizationmentioning

confidence: 99%

Disorder-induced topology in quench dynamics

Hsu,

Chiu,

Chang

2021

Preprint

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We study the effect of strong disorder on topology and entanglement in quench dynamics. Although disorderinduced topological phases have been well studied in equilibrium, the disorder-induced topology in quench dynamics has not been explored. In this work, we predict a disorder-induced topology of post-quench states characterized by the quantized dynamical Chern number and the crossings in the entanglement spectrum in (1 + 1) dimensions. The dynamical Chern number undergoes transitions from zero to unity, and back to zero when increasing disorder strength. The boundaries between different dynamical Chern numbers are determined by delocalized critical points in the post-quench Hamiltonian with the strong disorder. An experimental realization in quantum walks is discussed.

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Enhanced non-Markovian behavior in quantum walks with Markovian disorder

Cited by 27 publications

References 51 publications

Demonstration of non-Markovian process characterisation and control on a quantum processor

Demonstration of non-Markovian process characterisation and control on a quantum processor

Characterization of anomalous diffusion in one-dimensional quantum walks

Disorder-induced topology in quench dynamics

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