On Bose–Einstein condensation in Josephson junctions star graph arrays

Lorenzo, M.; Lucci, M.; Merlo, V.; Ottaviani, I.; Salvato, M.; Cirillo, M.; Müller, F.; Weimann, T.; Castellano, M. G.; Chiarello, F.; Torrioli, G.

doi:10.1016/j.physleta.2013.12.032

Cited by 21 publications

(24 citation statements)

References 13 publications

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“…However in multiple experiments 16 – 20 there was no direct evidence of this normal layer. More recently the observation of large currents in Nb-AlO -Nb Josephson junctions arrays were ascribed to experimental evidence of nonuniform boson distribution 21 – 23 . This was attributed to Bose–Einstein condensation and boson hopping 22 , 23 between superconducting islands of the array.…”

Section: Introductionmentioning

confidence: 99%

“…More recently the observation of large currents in Nb-AlO -Nb Josephson junctions arrays were ascribed to experimental evidence of nonuniform boson distribution 21 – 23 . This was attributed to Bose–Einstein condensation and boson hopping 22 , 23 between superconducting islands of the array. In this work, based on the assumption of Cooper pairs behaving as bosons, we derive a theory for the current flow of bosons across a S/I/S tunnel junction.…”

Section: Introductionmentioning

confidence: 99%

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Quantum tunneling theory of Cooper pairs as bosonic particles

Patiño

Lozano-Gómez

2021

Sci Rep

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We propose a simple phenomenological theory for quantum tunneling of Cooper pairs, in superconductor/insulator/superconductor tunnel junctions, for a regime where the system can be modeled as bosonic particles. Indeed, provided there is an absence of quasiparticle excitations (fermions), our model reveals a rapid increase in tunneling current, around zero bias voltage, which rapidly saturates. This manifests as a zero bias conductance peak that strongly depends on the superconductors temperature in a non-monotonic way. This low energy tunneling of Cooper pairs could serve as an alternative explanation for a number of tunneling experiments where zero bias conductance peak has been observed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quantum tunneling theory of Cooper pairs as bosonic particles

Patiño

Lozano-Gómez

2021

Sci Rep

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“…Several experiments have been performed in which evidence of boson distribution gradients in planar arrays, with specific topological structures, has been provided [ 18 , 19 , 20 , 21 ]. In these experiments the distribution of bosons on the islands was probed measuring current-voltage characteristics of series arrays of the Josephson junctions originated by oxide barriers between the superconductive islands; the junctions were also providing the coupling potential.…”

Section: Introductionmentioning

confidence: 99%

Josephson Currents and Gap Enhancement in Graph Arrays of Superconductive Islands

Lucci

Cassi

Merlo

et al. 2021

Entropy

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Evidence is reported that topological effects in graph-shaped arrays of superconducting islands can condition superconducting energy gap and transition temperature. The carriers giving rise to the new phase are couples of electrons (Cooper pairs) which, in the superconducting state, behave as predicted for bosons in our structures. The presented results have been obtained both on star and double comb-shaped arrays and the coupling between the islands is provided by Josephson junctions whose potential can be tuned by external magnetic field or temperature. Our peculiar technique for probing distribution on the islands is such that the hopping of bosons between the different islands occurs because their thermal energy is of the same order of the Josephson coupling energy between the islands. Both for star and double comb graph topologies the results are in qualitative and quantitative agreement with theoretical predictions.

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“…With respect to the problems currently studied as regards ground states of a Bose-Einstein condensate and to the rigorous derivation of equation (6) obtained in [17], let us stress two remarkable differences: first, we consider a focusing nonlinearity, second, we set the problem on a graph. Both features have nowadays an established experimental counterpart: on the one hand, self-concentrating condensates are currently realised [19], on the other hand, condensation on graph-like structures has been recently observed in [29].…”

Section: Introductionmentioning

confidence: 99%

Negative Energy Ground States for the L 2-Critical NLSE on Metric Graphs

Adami

Serra

Tilli

2016

Commun. Math. Phys.

177

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We investigate the existence of ground states with prescribed mass for the focusing nonlinear Schrödinger equation with L 2 -critical power nonlinearity on noncompact quantum graphs. We prove that, unlike the case of the real line, for certain classes of graphs there exist ground states with negative energy for a whole interval of masses.A key role is played by a thorough analysis of Gagliardo-Nirenberg inequalities and on estimates of the optimal constants. Most of the techniques are new and suited to the investigation of variational problems on metric graphs.

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On Bose–Einstein condensation in Josephson junctions star graph arrays

Cited by 21 publications

References 13 publications

Quantum tunneling theory of Cooper pairs as bosonic particles

Quantum tunneling theory of Cooper pairs as bosonic particles

Josephson Currents and Gap Enhancement in Graph Arrays of Superconductive Islands

Negative Energy Ground States for the L 2-Critical NLSE on Metric Graphs

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