Supercurrent Flow in Multiterminal Graphene Josephson Junctions

Draelos, Anne; Wei, Ming; Seredinski, Andrew; Li, Hengming; Mehta, Yash; Watanabe, Kenji; Taniguchi, Takashi; Borzenets, Ivan; Amet, François; Finkelstein, Gleb

doi:10.1021/acs.nanolett.8b04330

Cited by 92 publications

(84 citation statements)

References 32 publications

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“…Moreover, new states of matter based on ABS have been predicted in conventional superconductor multi-terminal devices, offering the possibility to engineer artificial topological materials featuring Weyl singularities [12][13][14][15] . We note that recent works aiming at probing these topological systems have been reported 16,17 . Experiments on multiterminal superconducting junctions have been already performed [18][19][20] , highlighting multiple Andreev reflections (MAR) involving more than two leads [21][22][23] as well as correlations between Cooper pairs [24][25][26][27][28] .…”

Section: Introductionmentioning

confidence: 92%

Engineering the Floquet spectrum of superconducting multiterminal quantum dots

et al. 2019

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Here we present a theoretical investigation of the Floquet spectrum in multiterminal quantum dot Josephson junctions biased with commensurate voltages. We first draw an analogy between the electronic band theory and superconductivity which enlightens the time-periodic dynamics of the Andreev bound states. We then show that the equivalent of the Wannier-Stark ladders observed in semiconducting superlattices via photocurrent measurements, appears as specific peaks in the finite frequency current fluctuations of superconducting multiterminal quantum dots. In order to probe the Floquet-Wannier-Stark ladder spectra, we have developed an analytical model relying on the sharpness of the resonances. The charge-charge correlation function is obtained as a factorized form of the Floquet wave-function on the dot and the superconducting reservoir populations. We confirm these findings by Keldysh Green's function calculations, in particular regarding the voltage and frequency dependence of the resonance peaks in the current-current correlations. Our results open up a road-map to quantum correlations and coherence in the Floquet dynamics of superconducting devices.

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Section: Introductionmentioning

confidence: 92%

Engineering the Floquet spectrum of superconducting multiterminal quantum dots

et al. 2019

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“…By increasing the number of terminals, one can access a higher dimensional phase space spanned by the relative phases or voltages between the several terminals. This can lead to new effects, such as interactions between supercurrents [22,23], coexistence of dissipative currents and supercurrents [24], multi-loop superconducting interferometry [25], or generalizations of * vpribiag@umn.edu all pair-wise currents flow through a small number of modes. The topological phase transitions in the Andreev levels manifest quantized conductances and transconductances which change as a function of the terminal phases and/or voltages.…”

Section: Introductionmentioning

confidence: 99%

Transport studies in a gate-tunable three-terminal Josephson junction

et al. 2020

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Josephson junctions with three or more superconducting leads have been predicted to exhibit topological effects in the presence of few conducting modes within the interstitial normal material. Such topological behavior manifests itself as signatures in the transport properties between different terminals, with topological phase transitions occurring as a function of phase and voltage bias. Here we study the superconducting properties of a top-gated three-terminal Josephson device, based on an InAs heterostructure two-dimensional electron gas (2DEG) proximitized with epitaxial aluminum. The top gate is used to control the 2DEG carrier density, and differential resistances are analyzed under various bias currents and magnetic fields. We find that the character of the features in a 2D resistance map of the device substantially change under different gate and magnetic field conditions. A computational model of a network of three resistively and capacitively shunted junctions (RCSJ) suggests that depletion of the interstitial 2DEG drives the system further toward this non-interacting network regime. A perpendicular magnetic field has the opposite effect of increasing interactions between supercurrents in each branch.

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“…These possibilities and advances motivate our work to investigate how universal mesoscopic effects manifest in topological Josephson junctions that, in particular, host Majorana states (see the review in [30] and references therein). We carry out this analysis in the context of multiterminal devices that were brought into the spotlight of recent theoretical attention with the observation that they can emulate topological matter [31][32][33][34][35][36][37][38][39], which triggered experimental efforts in realizing these systems in various proximitized circuits [40][41][42][43][44].…”

Section: Introductionmentioning

confidence: 99%

Topological supercurrents interaction and fluctuations in the multiterminal Josephson effect

Xie

Levchenko

2019

Phys. Rev. B

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We study the Josephson effect in the multiterminal junction of topological superconductors. We use the symmetry-constrained scattering matrix approach to derive band dispersions of emergent sub-gap Andreev bound states in a multidimensional parameter space of superconducting phase differences. We find distinct topologically protected band crossings that serve as monopoles of finite Berry curvature. Particularly, in a four-terminal junction the admixture of 2π and 4π periodic levels leads to the appearance of finite-energy Majorana-Weyl nodes. This topological regime in the junction can be characterized by a quantized nonlocal conductance that measures the Chern number of the corresponding bands. In addition, we calculate current-phase relations, variance, and cross-correlations of topological supercurrents in multiterminal contacts and discuss the universality of these transport characteristics. At the technical level these results are obtained by integrating over the group of a circular ensemble that describes the scattering matrix of the junction. We briefly discuss our results in the context of observed fluctuations of the gate dependence of the critical current in topological planar Josephson junctions and comment on the possibility of parity measurements from the switching current distributions in multiterminal Majorana junctions.

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Supercurrent Flow in Multiterminal Graphene Josephson Junctions

Cited by 92 publications

References 32 publications

Engineering the Floquet spectrum of superconducting multiterminal quantum dots

Engineering the Floquet spectrum of superconducting multiterminal quantum dots

Transport studies in a gate-tunable three-terminal Josephson junction

Topological supercurrents interaction and fluctuations in the multiterminal Josephson effect

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