Quantum dynamics in the interacting Fibonacci chain

Cecilia, Chiaracane,; Pietracaprina, Francesca; Purkayastha, Archak; Goold, John

doi:10.1103/physrevb.103.184205

Cited by 21 publications

(13 citation statements)

References 54 publications

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“…In absence of dephasing, the Fibonacci model shows anomalous transport which continously varies from superdiffusive to subdiffusive as a function of the Fibonacci potential strength. This fact was previously known in the limit of infinite temperature for particle or spin transport [41][42][43]. We demonstrate that this fact survives at finite temperatures, and is observable in both electric and thermal transport, even in the presence of both temperature and chemical potential biases.…”

Section: Discussionsupporting

confidence: 68%

“…To reduce this dependence on choice of system sizes, we use the averaging procedure adopted in Refs. [38,41,42]. In order to treat arbitrary lengths N which do not belong to the Fibonacci sequence, we cut finite samples of length N out of a long Fibonacci potential sequence C k , with k such that F k N .…”

Section: Fibonacci Modelmentioning

confidence: 99%

“…The Fibonacci quasicrystal has unusual properties such as a critical energy spectrum across all energy scales [21,[38][39][40], without a localization transition. This spectral criticality gives rise to anomalous transport exponents varying continuously with the potential strength, so that it is possible to tune the transport regime from superdiffusive to subdiffusive [25,39,[41][42][43].…”

Section: Introductionmentioning

confidence: 99%

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Dephasing-enhanced performance in quasiperiodic thermal machines

Chiaracane,

Purkayastha,

Mitchison

et al. 2021

Preprint

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Understanding and controlling quantum transport in low-dimensional systems is pivotal for heat management at the nanoscale. One promising strategy to obtain the desired transport properties is to engineer particular spectral structures. In this work we are interested in quasiperiodic disorder -incommensurate with the underlying periodicity of the lattice -which induces fractality in the energy spectrum. A well known example is the Fibonacci model which, despite being non-interacting, yields anomalous diffusion with a continuously varying dynamical exponent smoothly crossing over from superdiffusive to subdiffusive regime as a function of potential strength. We study the finite-temperature electric and heat transport in this model in the absence and in the presence of dephasing. Dephasing causes both thermal and electric transport to become diffusive, thereby making thermal and electrical conductivities finite in the thermodynamic limit. Thus, in the subdiffusive regime it leads to enhancement of transport. We find that the thermal and electric conductivities have multiple peaks as a function of dephasing strength. Remarkably, we observe that the thermal and electrical conductivities are not proportional to each other, a clear violation of Wiedemann-Franz law, and the position of their maxima can differ. We argue that this feature can be utilized to enhance performance of quantum thermal machines. In particular, we show that by tuning the strength of the dephasing we can enhance the performance of the device in regimes where it acts as an autonomous refrigerator.

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Section: Discussionsupporting

confidence: 68%

Section: Fibonacci Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dephasing-enhanced performance in quasiperiodic thermal machines

Chiaracane,

Purkayastha,

Mitchison

et al. 2021

Preprint

Self Cite

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“…( 22) and the constant c is chosen in such a way that ρ r + c has nonnegative eigenvalues. Then, the correlation function can be rewritten as a standard expectation value [7,57,80],…”

Section: A Dynamical Quantum Typicalitymentioning

confidence: 99%

Quantum versus classical dynamics in spin models: Chains, ladders, and square lattices

et al. 2021

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We present a comprehensive comparison of spin and energy dynamics in quantum and classical spin models on different geometries, ranging from one-dimensional chains, over quasi-one-dimensional ladders, to twodimensional square lattices. Focusing on dynamics at formally infinite temperature, we particularly consider the autocorrelation functions of local densities, where the time evolution is governed either by the linear Schrödinger equation in the quantum case or the nonlinear Hamiltonian equations of motion in the case of classical mechanics. While, in full generality, a quantitative agreement between quantum and classical dynamics can therefore not be expected, our large-scale numerical results for spin-1/2 systems with up to N = 36 lattice sites in fact defy this expectation. Specifically, we observe a remarkably good agreement for all geometries, which is best for the nonintegrable quantum models in quasi-one or two dimensions, but still satisfactory in the case of integrable chains, at least if transport properties are not dominated by the extensive number of conservation laws. Our findings indicate that classical or semiclassical simulations provide a meaningful strategy to analyze the dynamics of quantum many-body models, even in cases where the spin quantum number S = 1/2 is small and far away from the classical limit S → ∞.

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“…Recently, it was shown theoretically [12][13][14][15][16][17][18] and experimentally [19][20][21] that besides randomly distributed disorder, quasiperiodic systems can also host MBL phases. Noninteracting quasiperiodic systems show richer local- * as3157@cam.ac.uk ization phenomena in one dimension compared to randomly disordered systems.…”

Section: Introductionmentioning

confidence: 99%

Many-body localization in the interpolating Aubry-André-Fibonacci model

Štrkalj,

Doggen,

Gornyi

et al. 2021

Preprint

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We investigate the localization properties of a spin chain with an antiferromagnetic nearestneighbour coupling, subject to an external quasiperiodic on-site magnetic field. The quasiperiodic modulation interpolates between two paradigmatic models, namely the Aubry-André and the Fibonacci models. We find that stronger many-body interactions extend the ergodic phase in the former, whereas they shrink it in the latter. Furthermore, the many-body localization transition points at the two limits of the interpolation appear to be continuously connected along the deformation. As a result, the position of the many-body localization transition depends on the interaction strength for an intermediate degree of deformation. Moreover, in the region of parameter space where the single-particle spectrum contains both localized and extended states, many-body interactions induce an anomalous effect: weak interactions localize the system, whereas stronger interactions enhance ergodicity. We map the model's localization phase diagram using the decay of the quenched spin imbalance in relatively long chains. This is accomplished employing a time-dependent variational approach applied to a matrix product state decomposition of the many-body state. Our model serves as a rich playground for testing many-body localization under tunable potentials.

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Quantum dynamics in the interacting Fibonacci chain

Cited by 21 publications

References 54 publications

Dephasing-enhanced performance in quasiperiodic thermal machines

Dephasing-enhanced performance in quasiperiodic thermal machines

Quantum versus classical dynamics in spin models: Chains, ladders, and square lattices

Many-body localization in the interpolating Aubry-André-Fibonacci model

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