Observation of Photon-Assisted Noise in a Diffusive Normal Metal–Superconductor Junction

Кожевников, А. А.; Schoelkopf, R. J.; Prober, D. E.

doi:10.1103/physrevlett.84.3398

Cited by 145 publications

(147 citation statements)

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“…Thus, in this process a charge transfer of 2e occurs, but with a reduced probability, since two particles have to tunnel. The shot noise is proportional to the charge of the elementary processes, and one thus naivly expects a doubling of the shot noise, which was indeed found theoretically [12,13] and experimentally [14,15] for diffusive conductors. It is remarkable that this doubling occurs for diffusive conductors, whereas it is not found for other conductors like, e. g., single-channel contacts [3,12,[16][17][18] , double tunnel junctions [19][20][21][22], or diffusive junctions with a tunneling barrier [23,24].…”

Section: Introductionmentioning

confidence: 89%

Shot Noise in Mesoscopic Diffusive Andreev Wires

Belzig

2004

Molecular Nanowires and Other Quantum Objects

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We study shot noise in mesoscopic diffusive wires between a normal and a superconducting terminal. We particularly focus on the regime, in which the proximity-induced reentrance effect is important. We will examine the difference between a simple Boltzmann-Langevin description, which neglects induced correlations beyond the simple conductivity correction, and a full quantum calculation. In the latter approach, it turns out that two Andreev pairs propagating coherently into the normal metal are anti-correlated for E Ec, where Ec = D/L 2 is the Thouless energy. In a fork geometry the flux-sensitive suppression of the effective charge was confirmed experimentally.

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Section: Introductionmentioning

confidence: 89%

Shot Noise in Mesoscopic Diffusive Andreev Wires

Belzig

2004

Molecular Nanowires and Other Quantum Objects

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“…Eq. (7) constitutes the starting point for computing both finite frequency noise and the zero frequency noise in the presence of a local harmonic perturbation, such as in the Non Stationary AB effect in NS junctions 7 which was recently detected experimentally 6 . Here it constitutes the starting point for the computation of the density-density correlator, and it is valid both in the Andreev regime and above gap, provided that the proper distribution functions are specified on the superconducting side.…”

Section: Current and Density Fluctuationsmentioning

confidence: 99%

“…In the Andreev regime, at zero temperature, it is expected that the calculation of the decoherence rate is similar to that of a normal metal point contact except that the charge of the carriers is replaced by the Cooper pair charge 6 . This simple analogy fails both at finite temperatures and at voltage biases superior to the superconducting gap.…”

Section: Introductionmentioning

confidence: 99%

Tunable decoherence in the vicinity of a normal metal–superconducting junction

2001

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The decoherence rate of a quantum dot coupled to a fluctuating environment described by a normal-metal superconductor junction is considered. The density-density correlator at low frequencies constitutes the kernel which enters the calculation of the phase coherence time. The density fluctuations are connected to the finite frequency current-current correlations in the point contact via the continuity equation. Below and above the gap, at zero temperature the density correlator contains spatial oscillations at half of the Fermi wave length on the normal side. As the bias crosses the superconducting gap, the opening of new scattering channels enhances the decoherence rate dramatically, suggesting the possibility of tuning the decoherence rate in a controllable manner.

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“…(7), calculating the corresponding T N (x i ) by means of (2) and averaging them over the corresponding segments, one easily obtains that T 1 = T 3 = eV /6 and T 2 = T 4 = eV /4. From this, one readily obtains the cross-correlated spectral densities by means of (6). Taking into account that the average current flowing between the normal electrodes is I = eV /2R, the expression for the noise at the normal ends may be written in the form…”

mentioning

confidence: 99%

“…2,3 This doubling was interpreted as an effective doubling of electron charge and has been experimentally confirmed in a number of papers. [4][5][6] Quite recently, it was shown that the doubled shot noise in diffusive NS contacts survives at finite voltages of the order of the energy gap. 7 Moreover, this noise does not require a phase coherence 8 and may be described in terms of a semiclassical Boltzmann -Langevin equation.…”

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confidence: 99%

Nonlocal effects in the shot noise of diffusive superconductor–normal-metal systems

Nagaev

2001

Phys. Rev. B

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A cross-shaped diffusive system with two superconducting and two normal electrodes is considered. A voltage eV < ∆ is applied between the normal leads. Even in the absence of average current through the superconducting electrodes their presence increases the shot noise at the normal electrodes and doubles it in the case of a strong coupling to the superconductors. The nonequilibrium noise at the superconducting electrodes remains finite even in the case of a vanishingly small transport current due to the absence of energy transfer into the superconductors. This noise is suppressed by electron-electron scattering at sufficiently high voltages.PACS numbers: 72.70.+m, 74.40+k, 74.50+r Recently, the noise properties of hybrid systems involving superconducting (S) and normal (N) metals became a subject of intensive studies. 1 A key effect in these properties is the Andreev reflection, in which electrons incident from the normal metal are reflected from the NS interface as holes. In particular, it was found that in the zero-voltage limit, the shot noise in diffusive NS contacts with phase-coherent transport is doubled with respect to its value in a normal contact with the same resistance. 2,3 This doubling was interpreted as an effective doubling of electron charge and has been experimentally confirmed in a number of papers. [4][5][6] Quite recently, it was shown that the doubled shot noise in diffusive NS contacts survives at finite voltages of the order of the energy gap. 7 Moreover, this noise does not require a phase coherence 8 and may be described in terms of a semiclassical Boltzmann -Langevin equation. 9 In this approach, the increased noise in NS systems is due to an excess heating of electron gas rather than to the doubling of the effective charge.Along with studying the shot noise in two-terminal systems, a considerable attention received the noise in multiterminal structures. It was found that the noise of normal-metal diffusive structures with more than two electrodes may exhibit exchange effects 10 and nonlocal effects. 11 The latter imply that the noise in the system is affected by a presence of open contacts even in the absence of average current flow through them.Several authors also calculated current correlations in single-channel multiterminal NS systems. 12-14 In particular, it was found that the noise measured at the two normal electrodes in a four-terminal system depends on the phase difference between the two superconducting electrodes. 12 A current noise was also calculated at a tip placed on a multimode quantum-coherent NS structure. 15 In this paper, we consider nonlocal effects in multiterminal mesoscopic diffusive SN systems using the semiclassical description of noise. In particular, we report on a semiclassical "proximity" effect in the noise where the current noise in a normal conductor is increased by its contact with a superconductor. Another finding is that under certain conditions, a large noise may be induced in an SNS structure even by a small transverse transport current.Consi...

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Observation of Photon-Assisted Noise in a Diffusive Normal Metal–Superconductor Junction

Cited by 145 publications

References 20 publications

Shot Noise in Mesoscopic Diffusive Andreev Wires

Shot Noise in Mesoscopic Diffusive Andreev Wires

Tunable decoherence in the vicinity of a normal metal–superconducting junction

Nonlocal effects in the shot noise of diffusive superconductor–normal-metal systems

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