Critical exponents for an impurity in a bosonic Josephson junction: Position measurement as a phase transition

Mumford, J.; O’Dell, D. H. J.

doi:10.1103/physreva.90.063617

Cited by 10 publications

(9 citation statements)

References 95 publications

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“…Recent realizations of this transition include both an actual superradiant transition in an optical cavity filled with an atomic BEC pumped from the side by a laser [77], and simulations in trapped ion systems [78]. In our case, the two levels of the impurity simulate the first two levels of the harmonic oscillator and, remarkably, this is enough to capture the critical properties of the Dicke model which are determined by the regime where the electromagnetic field is barely excited [69]. Another similarity between the Dicke model and the boson-impurity model is that both display regular dynamics in the normal phase and chaotic dynamics in the symmetry broken phase [68,79].…”

Section: Modelmentioning

confidence: 96%

“…Finite values of U excite particles into the antisymmetric mode and as |U | → ∞ the two modes become equally occupied so that Ŝx = 0. In the thermodynamic limit N → ∞ the QPT becomes sharp such that Ŝx = 0 for Λ > Λ c (normal phase) and takes finite values for Λ < Λ c (Z 2 symmetry broken phase) [68,69,80]. Therefore Ŝx is a good order parameter for this transition.…”

Section: Modelmentioning

confidence: 99%

See 1 more Smart Citation

Measuring out-of-time-ordered correlation functions with a single impurity qubit in a bosonic Josephson junction

Mumford

Kirkby

O’Dell

2020

J. Phys. B: At. Mol. Opt. Phys.

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We calculate the out-of-time-ordered correlation function (OTOC) of a single impurity qubit coupled to fully a connected many-particle system such as a bosonic Josephson junction or spins with long-range interactions. In these systems the qubit OTOC can be used to detect both ground state and excited state quantum phase transitions (QPTs), making it a robust order parameter that is considerably more sensitive than the standard one-body correlation function. Finite size scaling exponents for an N body system can also be accurately extracted from the long-time OTOC dynamics, however, for short times there is a discrepancy due to the fact that the qubit has not had enough time to couple to the larger system. Our results show that the OTOC of even the smallest probe is enough to diagnose a QPT in fully connected models but, like a continuous measurement, can still cause a backaction effect which leads to weakly chaotic dynamics and gradual information scrambling.

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Section: Modelmentioning

confidence: 96%

Section: Modelmentioning

confidence: 99%

Measuring out-of-time-ordered correlation functions with a single impurity qubit in a bosonic Josephson junction

Mumford

Kirkby

O’Dell

2020

J. Phys. B: At. Mol. Opt. Phys.

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“…Here, the polaronic behavior should strongly depend on the involved interactions and an intriguing prospect would be to engineer specific entangled polaron states in certain interaction regimes with an additional knob provided by the interspecies mass-imbalance. Moreover, we should also emphasize that these hybridized systems are of further interest due to the fact that one subsystem (impurity) lies in the deep quantum regime while the other one (medium) can be potentially described semi-classically [72][73][74][75][76][77]. For instance, it has been demonstrated that following an impurity-bath interaction quench leads to chaotic signatures in the dynamics of the bath accompanied by significant coherence losses [77].…”

Section: Introductionmentioning

confidence: 99%

Intra- and interband excitations induced residue decay of the Bose polaron in a one-dimensional double-well

Chen¹,

Mistakidis

Schmelcher

2022

New J. Phys.

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We investigate the polaronic properties of a single impurity immersed in a weakly interacting bosonic environment confined within a one-dimensional double-well potential using an exact diagonalization approach. We find that an increase of the impurity-bath coupling results in a vanishing residue, signifying the occurrence of the polaron orthogonality catastrophe. Asymptotic configurations of the systems' ground state wave function in the strongly interacting regime are obtained by means of a Schmidt decomposition, which in turn accounts for the observed orthogonality catastrophe of the polaron. We exemplify that depending on the repulsion of the Bose gas, three distinct residue behaviors appear with respect to the impurity-bath coupling. These residue regimes are characterized by two critical values of the bosonic repulsion and originate from the interplay between the intra- and the interband excitations of the impurity. Moreover, they can be clearly distinguished in the corresponding species reduced density matrices with the latter revealing a phase separation on either the one- or the two-body level. The impact of the interspecies mass-imbalance on the impurity's excitation processes is appreciated yielding an interaction shift of the residue regions. Our results explicate the interplay of intra- and interband excitation processes for the polaron generation in multiwell traps and for designing specific polaron entangled states motivating their exposure in current experiments.

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“…In the present paper, we investigate a binary ultracold atomic mixture made of a single impurity and a noninteracting many-body bosonic ensemble that are confined within a 1D DW potential. Unlike most of the previous studies where the focuses are put on the weak-interacting regime, rendering the impurity being restricted into the lowest two modes of the DW potential [51][52][53][54][55][56], our discussions are not restricted to such a scenario. Specifically, we study the onset of the chaos for the majority bosonic species due to the presence of the impurity and put particular emphasis on the its dynamical response upon a sudden quench of the impurity-Bose interaction strength.…”

Section: Introductionmentioning

confidence: 99%

Impurity induced quantum chaos for an ultracold bosonic ensemble in a double-well

Chen,

Keiler,

Xianlong

et al. 2021

Preprint

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We demonstrate that an ultracold many-body bosonic ensemble confined in a one-dimensional (1D) doublewell (DW) potential can exhibit chaotic dynamics due to the presence of a single impurity. The non-equilibrium dynamics is triggered by a quench of the impurity-Bose interaction and is illustrated via the evolution of the population imbalance for the bosons between the two wells. While the increase of the post-quench interaction strength always facilitates the irregular motion for the bosonic population imbalance, it becomes regular again when the impurity is initially populated in the highly excited states. Such an integrability to chaos (ITC) transition is fully captured by the transient dynamics of the corresponding linear entanglement entropy, whose infinite-time averaged value additionally characterizes the edge of the chaos and implies the existence of an effective Bose-Bose attraction induced by the impurity. In order to elucidate the physical origin for the observed ITC transition, we perform a detailed spectral analysis for the mixture with respect to both the energy spectrum as well as the eigenstates. Specifically, two distinguished spectral behaviors upon a variation of the interspecies interaction strength are observed. While the avoided level-crossings take place in the low-energy spectrum, the energy levels in the high-energy spectrum possess a band-like structure and are equidistant within each band. This leads to a significant delocalization of the low-lying eigenvectors which, in turn, accounts for the chaotic nature of the bosonic dynamics. By contrast, those highly excited states bear a high resemblance to the noninteracting integrable basis, which explains for the recovery of the integrability for the bosonic species. Finally, we discuss the induced Bose-Bose attraction as well as its impact on the bosonic dynamics.

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Critical exponents for an impurity in a bosonic Josephson junction: Position measurement as a phase transition

Cited by 10 publications

References 95 publications

Measuring out-of-time-ordered correlation functions with a single impurity qubit in a bosonic Josephson junction

Measuring out-of-time-ordered correlation functions with a single impurity qubit in a bosonic Josephson junction

Intra- and interband excitations induced residue decay of the Bose polaron in a one-dimensional double-well

Impurity induced quantum chaos for an ultracold bosonic ensemble in a double-well

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