Quantum dynamics of the small-polaron formation in a superconducting analog simulator

Stojanović, Vladimir; Salom, Igor

doi:10.1103/physrevb.99.134308

Cited by 17 publications

(14 citation statements)

References 60 publications

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“…It is worthwhile to mention that a similar sharp transition was found 47,48 in a model where Peierls-type coupling is complemented by e-ph interaction of the breathing-mode type 26 . It is important to stress that a dependence on both the excitation and phonon quasimomenta (k, q) is not a sufficient condition for the existence of a ground-state nonanalyticity; a counterexample is furnished, e.g., by the Edwards model 36,37,40 .…”

Section: A Hamiltonian Of the Systemsupporting

confidence: 69%

Entanglement-spectrum characterization of ground-state nonanalyticities in coupled excitation-phonon models

Stojanović

2020

Phys. Rev. B

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The polaron concept captures physical situations involving an itinerant quantum particle (excitation) that interacts strongly with bosonic degrees of freedom and becomes heavily boson-dressed. While the Gerlach-Löwen theorem rules out the occurrence of nonanalyticities of ground-staterelated quantities for a broad class of polaron models, examples were found in recent years of sharp transitions pertaining to strongly momentum-dependent interactions of an excitation with dispersionless (zero-dimensional) phonons. On the example of a lattice model with Peierls-type excitationphonon interaction, such level-crossing-type small-polaron transitions are analyzed here through the prism of the entanglement spectrum of the excitation-phonon system. By evaluating this spectrum in a numerically-exact fashion it is demonstrated that the behavior of the entanglement entropy in the vicinity of the critical excitation-phonon coupling strength chiefly originates from one specific entanglement-spectrum eigenvalue, namely the smallest one. While the discrete translational symmetry of the system implies that those eigenvalues can be labeled by the bare-excitation quasimomentum quantum numbers, here it is shown numerically that they are predominantly associated to the quasimomenta 0 and π, including cases where a transition between the two takes place deeply in the strong-coupling regime.

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Section: A Hamiltonian Of the Systemsupporting

confidence: 69%

Entanglement-spectrum characterization of ground-state nonanalyticities in coupled excitation-phonon models

Stojanović

2020

Phys. Rev. B

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“…Firstly, while all the examples of state-engineering in the present work pertained to a three-atom (qubit) system, the preparation of general twisted W states in lattice-periodic systems is of utmost importance in the area of analog quantum simulation [66,67]. Namely, owing to their known connection with single-excitation Bloch states, such states represent the desired states of analog simulators [68][69][70][71] prior to performing interaction quenches of various types [72]. Secondly, while our proposed state-conversion scheme is characterized by timescale hierarchies, it would be instructive to devise its counterparts based on controlled dissipation [63,64].…”

Section: Discussionmentioning

confidence: 99%

Dynamical generation of chiral $W$ and Greenberger-Horne-Zeilinger states in laser-controlled Rydberg-atom trimers

Haase,

Alber,

Stojanovic

2021

Preprint

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Owing to the significantly improved scalability of optically-trapped neutral-atom systems, which makes the prospect of large-scale quantum computing increasingly realistic, extensive efforts have been devoted in recent years to quantum-state engineering in Rydberg-atom ensembles. Motivated by this spate of research activity, we investigate the problem of engineering generalized ("twisted") W states, as well as Greenberger-Horne-Zeilinger (GHZ) states, in the Rydberg-blockade regime of a neutral-atom system. We assume that each atom in the envisioned system initially resides in its ground state and is subject to several external laser pulses that are close to being resonant with the same internal atomic transition. In particular, in the special case of a three-atom system (Rydberg-atom trimer) we determine configurations of field alignments and atomic positions that enable the realization of chiral W states -a special type of twisted three-qubit W states of interest for implementing noiseless-subsystem qubit encoding. In addition, we also address the problem of interconversion between twisted W and GHZ states in the same three-atom system, thus generalizing our recent work that involves ordinary W states [T. Haase et al., Phys. Rev. A 103, 032427 (2021)]. Compared to this previous study, our principal finding is that starting from twisted W states is equivalent to renormalizing downwards the relevant Rabi frequencies. Consequently, a larger laser pulse energy is required to carry out the desired state conversion within the same time frame.

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“…On the other hand, the obtained feature of the phonon spectral function reflects the structure of low-energy excited polaronic states in the crossover regime. In polaron models with other types of short-range electron-phonon interaction, also up to three excited states have been found below the one-phonon continuum from the onset of the strong coupling regime [67][68][69]. So this appears to be a generic characteristic of such systems.…”

Section: Phonon Spectral Functionmentioning

confidence: 93%

Polaron transformations in the realistic model of the strongly correlated electron system

et al. 2020

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Electron-phonon coupling, diagonal in a real space formulation, leads to a polaron paradigm of smoothly varying properties. However, fundamental changes, namely the singular behavior of polarons, occur if offdiagonal pairing is involved into consideration. The study of polaron transformations and related properties of matter is of particular interest for realistic models, since competition between diagonal and off-diagonal electron-phonon contributions in the presence of other strong interactions can result in unconventional behavior of the system. Here we consider a two-dimensional multiband pd model of cuprate superconductors with electron-phonon interaction and analyze the features of the systems that are caused by the competition of diagonal and off-diagonal electron-phonon contributions in the limit of strong electron correlations. Using the polaronic version of the generalized tight-binding method, we describe the evolution of the band structure, Fermi surface, density of states at Fermi level, and phonon spectral function in the space of electron-phonon parameters ranging from weak to strong coupling strength of the adiabatic limit. On the phase diagram of polaron properties we reveal two quantum phase transitions and show how electron-phonon interaction gives rise to Fermi surface transformation (i) from hole pockets to true Fermi arcs and (ii) from hole to electron type of conductivity. We also demonstrate the emergence of new states in the phonon spectral function of the polaron and discuss their origin.

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Quantum dynamics of the small-polaron formation in a superconducting analog simulator

Cited by 17 publications

References 60 publications

Entanglement-spectrum characterization of ground-state nonanalyticities in coupled excitation-phonon models

Entanglement-spectrum characterization of ground-state nonanalyticities in coupled excitation-phonon models

Dynamical generation of chiral $W$ and Greenberger-Horne-Zeilinger states in laser-controlled Rydberg-atom trimers

Polaron transformations in the realistic model of the strongly correlated electron system

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