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Zorin, A. B.; Lotkhov, S. V.; Pashkin, Yu. A.; Zangerle, H.; Krupenin, V. A.; Weimann, Thomas; Scherer, H.; Niemeyer, J.

doi:10.1023/a:1007780925567

Cited by 17 publications

(16 citation statements)

References 21 publications

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“…At low temperature, it is equivalent to a single junction whose Josephson energy is modulated with a 2e period by the gate charge coupled to the island formed between the two junctions. This modulation can be exploited for low-noise-temperature electrometry [23], provided that the device supercurrent is measured like in the present experiment. The SCPT could operate at high frequencies since intrinsic bandwidths up to 120 and 250 MHz have been demonstrated for arrays with 100 and 30 SQUIDs, respectively [24].…”

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confidence: 97%

Direct Measurement of the Josephson Supercurrent in an Ultrasmall Josephson Junction

et al. 2001

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We have measured the supercurrent flowing through a nonhysteretic, ultrasmall, voltage-biased Josephson junction. In contrast with experiments performed so far on hysteretic Josephson junctions, we find a supercurrent peak whose maximum I(s max) increases as the temperature T decreases. The asymptotic T = 0 value of I(s max) agrees with the junction Ambegaokar-Baratoff critical current, as predicted by theory.

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confidence: 97%

Direct Measurement of the Josephson Supercurrent in an Ultrasmall Josephson Junction

et al. 2001

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“…This device is an electrometer, dual to the DC SQUID amplifier [154,155] shown in (g). The QPST is similar to a single Cooper-pair transistor (SCPT) [156]; however, it could have a much higher sensitivity than an SCPT, which is limited by the charging energy of the JJs (by how small one can make the junction capacitance). The QPST is instead limited by the kinetic capacitance C k , whose ultimate limit is the series capacitance of the wires, which can be much smaller.…”

Section: Appendix F Flux-charge Duality and Lumped-element Supercondmentioning

confidence: 99%

Flux–charge duality and topological quantum phase fluctuations in quasi-one-dimensional superconductors

Kerman

2013

New J. Phys.

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It has long been thought that macroscopic phase coherence breaks down in effectively lower-dimensional superconducting systems even at zero temperature due to enhanced topological quantum phase fluctuations. In quasione-dimensional wires, these fluctuations are described in terms of 'quantum phase-slip' (QPS): tunneling of the superconducting order parameter for the wire between states differing by ±2π in their relative phase between the wire's ends. Over the last several decades, many deviations from conventional bulk superconducting behavior have been observed in ultra-narrow superconducting nanowires, some of which have been identified with QPS. While at least some of the observations are consistent with existing theories for QPS, other observations in many cases point to contradictory conclusions or cannot be explained by these theories. Hence, our understanding of the nature of QPS, and its relationship to the various observations, has remained imcomplete. In this paper we present a new model for QPS which takes as its starting point an idea originally postulated by Mooij and Nazarov (2006 Nature Phys. 2 169): that flux-charge duality, a classical symmetry of Maxwell's equations, can be used to relate QPS to the well-known Josephson tunneling of Cooper pairs. Our model provides an alternative, and qualitatively different, conceptual basis for QPS and the phenomena which arise from it in experiments, and it appears to permit for the first time a unified understanding of observations across several different types of experiments and materials systems.

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“…1) is topologically a single-contact rf SQUID whose Josephson junction is replaced by a single-Cooper-pair transistor. 19,20,21,22 The latter consists of two mesoscopic junctions with Josephson energies E J1 , E J2 and capacitances C 1 , C 2 , coupled by a small island. The Hamiltonian of the charge-phase qubit in the eigenstate basis within the two-level approximation (E CP ≫ ε J (δ)) and the small-inductance limit reads as 2,19,20…”

Section: System Of Charge-phase Qubit and Tank Circuitmentioning

confidence: 99%

“…In general case, at arbitrary ratio of the Josephson and charging energies ε J (δ)/E CP (while the two-level approximation (1) is determined by ε J (δ)/E CP ≪ 1) the energy spectrum and eigenfunctions of the charge-phase qubit are given, respectively, by the Bloch bands E n (q, δ) and the Bloch wave functions |q, δ; n (n = 0, 1, 2... is the band index and q = en g the quasicharge) that are numerical solutions of Schrödinger equation with Hamiltonian containing all the charge states and periodic Josephson potential. 19,22 Then the lowest two energy levels n = 0, 1 form the basis of the charge-phase qubit, so…”

Section: System Of Charge-phase Qubit and Tank Circuitmentioning

confidence: 99%

Coherent Rabi response of a charge-phase qubit under microwave irradiation

2009

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We report on radio-frequency measurements of the charge-phase qubit being under continuous microwave irradiation in the state of weak coupling to a radio-frequency tank circuit. We studied the rf impedance dependence on the two important parameters such as power of microwave irradiation whose frequency is close to the gap between the two lowest qubit energy levels, and temperature of the internal heat bath. We have found that backaction effects of the qubit on the rf tank, and vice versa, tank on the qubit, lead to a negative as well as a positive real part of the qubit impedance ReZ(ω) seen by the tank. We have implemented noise spectroscopy measurements for direct impedance readout at the extreme points corresponding to maximum voltage response and obtained absolute values of about 0.017 Ω for the negative and positive ReZ(ω). Our results demonstrate the existence and persistence of the coherent single-and multi-photon Rabi dynamics of the qubit with both negative and positive dynamic resistance inserted into the tank in the temperature range of 10 to 200 mK.

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Untitled

Cited by 17 publications

References 21 publications

Direct Measurement of the Josephson Supercurrent in an Ultrasmall Josephson Junction

Direct Measurement of the Josephson Supercurrent in an Ultrasmall Josephson Junction

Flux–charge duality and topological quantum phase fluctuations in quasi-one-dimensional superconductors

Coherent Rabi response of a charge-phase qubit under microwave irradiation

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