Observation of parity-induced suppression of Josephson tunneling in the superconducting single electron transistor

Joyez, P.; Lafarge, P.; Filipe, A.; Estève, D.; Devoret, Michel

doi:10.1103/physrevlett.72.2458

Cited by 199 publications

(179 citation statements)

References 17 publications

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“…The modification of the Josephson current due to the parity effects was studied both theoretically 8 and experimentally. 9,10 These studies were concentrated on the case of small Josephson coupling energy (E J ӶE C ). A systematic investigation of the parity effects for an arbitrary E J /E C ratio seems to be an interesting open problem.…”

Section: Introductionmentioning

confidence: 99%

Cooper-pair tunneling in small junctions with tunable Josephson coupling

1996

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We investigate Cooper-pair tunneling in a circuit consisting of two dc-superconducting quantum interference devices in series, with a gate capacitively coupled to the central island. Measurements cover a wide range of values of the ratio between Josephson coupling energy E J and charging energy E C . The E J /E C ratio dependence of the supercurrent is well described by the orthodox theory provided that strong fluctuations of the Josephson phase due to the electromagnetic environment are taken into account. Our data can be interpreted in terms of squeezing of the charge fluctuations with decreasing E J /E C ratio. ͓S0163-1829͑96͒06533-2͔

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Section: Introductionmentioning

confidence: 99%

Cooper-pair tunneling in small junctions with tunable Josephson coupling

1996

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“…Electron-phonon-mediated pair recombination has been established as the canonical mechanism of QP decay 22 . Single-QP loss mechanisms in the presence of QP 'traps', such as normal metal contacts 7,16,17,23,24 , engineered gap inhomogeneity 8,25,26 , Andreev bound states 27 or magnetic field penetration 28,29 , have also been studied.…”

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confidence: 99%

Measurement and control of quasiparticle dynamics in a superconducting qubit

et al. 2014

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Superconducting circuits have attracted growing interest in recent years as a promising candidate for fault-tolerant quantum information processing. Extensive efforts have always been taken to completely shield these circuits from external magnetic fields to protect the integrity of the superconductivity. Here we show vortices can improve the performance of superconducting qubits by reducing the lifetimes of detrimental single-electron-like excitations known as quasiparticles. Using a contactless injection technique with unprecedented dynamic range, we quantitatively distinguish between recombination and trapping mechanisms in controlling the dynamics of residual quasiparticle, and show quantized changes in quasiparticle trapping rate because of individual vortices. These results highlight the prominent role of quasiparticle trapping in future development of superconducting qubits, and provide a powerful characterization tool along the way.

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“…The excess QP density close to the junction can be diminished by ©2011 American Physical Society fabricating very thick S electrodes, 16 or covering them partially by a layer of normal metal that acts as a QP trap. [18][19][20] The QP population is typically modeled in terms of a diffusion equation, describing their recombination retarded by phonon retrapping, and other loss mechanisms. [21][22][23][24][25] Converting the excess density into an effective, position-dependent temperature T (x), one finds 26,27 that at phonon temperatures k B T the S leads can be overheated on a length scale ranging from tens of micrometers to a millimeter, as the electron-phonon relaxation and electronic heat conduction are exponentially suppressed compared to their normal-state values.…”

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confidence: 99%

Magnetic-field-induced stabilization of nonequilibrium superconductivity in a normal-metal/insulator/superconductor junction

Peltonen¹,

Muhonen

Meschke³

et al. 2011

Phys. Rev. B

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A small magnetic field is found to enhance relaxation processes in a superconductor, thus stabilizing superconductivity in nonequilibrium conditions. In a normal-metal (N)/insulator/superconductor (S) tunnel junction, applying a field of the order of 100 μT leads to significantly improved cooling of the N island by quasiparticle (QP) tunneling. These findings are attributed to faster QP relaxation within the S electrodes as a result of enhanced QP drain through regions with a locally suppressed energy gap due to magnetic vortices in the S leads at some distance from the junction. Introduction. In this Rapid Communication, we report an observation that appears counterintuitive at first: A small magnetic field is found to stabilize superconductivity under quasiparticle (QP) injection. In our experiment, the cooling power of normal-metal (N)/insulator (I)/superconductor (S) tunnel structures is enhanced in perpendicular magnetic fields B ⊥ 100 μT = 1 G. A measured maximum temperature drop δT relative to a starting bath temperature T 0 = 285 mK exhibiting this behavior is shown in Fig. 1(a). The improvement is unexpected, as in general the effect of a magnetic field is to suppress superconductivity. Electronic cooling in NIS junctions in the presence of magnetic fields in both perpendicular and parallel orientations has been studied before, 1 but only in higher fields where the cooling power was already reduced due to a diminishing superconducting energy gap . On the other hand, the creation of magnetic vortices 2 has been shown to enhance QP relaxation in superconducting aluminum, as the QPs become trapped and thermalize in the regions of a reduced energy gap. 3 Here we demonstrate that the additional relaxation channel due to an enhanced QP drain through regions occupied by magnetic vortices enhances the superconducting performance of S leads and improves the electronic cooling in NIS junctions. This can be of relevance in superconducting qubits, 4-7 resonators, 8 and in hybrid SINIS turnstiles 9 in reducing the effects from nonequilibrium and residual QPs arising due to drive and microwave radiation from the environment. Moreover, improved relaxation caused by vortex creation in the S leads can partially explain the "reentrant superconductivity" observed in Zn and Al nanowires. 10,11 In the present case, as sketched in Fig. 1(a), vortex formation in the S electrodes away from the NIS junction improves relaxation of the injected QPs and leads to enhanced cooling of the N island. In higher fields, vortices move closer to the junction, deteriorating the cooling power.In a NIS junction, acts as an energy filter for the tunneling QP. [12][13][14][15] At low temperatures k B T and for bias voltages eV across the junction, the electrons in the N electrode cool considerably below the phonon temperature by hot QP extraction. The effect can be made to be more pronounced in a symmetric double-junction SINIS structure with a small N

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Observation of parity-induced suppression of Josephson tunneling in the superconducting single electron transistor

Cited by 199 publications

References 17 publications

Cooper-pair tunneling in small junctions with tunable Josephson coupling

Cooper-pair tunneling in small junctions with tunable Josephson coupling

Measurement and control of quasiparticle dynamics in a superconducting qubit

Magnetic-field-induced stabilization of nonequilibrium superconductivity in a normal-metal/insulator/superconductor junction

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