Quantum coherent effects, phase transitions, and the dissipative dynamics of ultra small tunnel junctions

Schön, Gerd; Zaikin, Andrei D.

doi:10.1016/0370-1573(90)90156-v

Cited by 862 publications

(1,023 citation statements)

References 163 publications

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“…They are dual to each other with respect to the exchange of the canonically conjugated quantum variables, phase and charge. This duality is exact, in contrast to the widely known 12 approximate self-duality of Josephson junction circuits. Results of ref.…”

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confidence: 74%

Superconducting nanowires as quantum phase-slip junctions

2006

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F or a superconductor, charge and phase are dual quantum variables. A phase-slip event in a superconducting nanowire changes the phase difference over the wire by 2π; it is the dual process to Cooper-pair tunnelling in a Josephson junction. Phase slip by thermal activation at high temperatures is well understood 1 . Phase slip by quantum tunnelling at low temperatures is considered plausible 2,3 , but experiments on the resistance of nanowires 4,5 are inconclusive on this point. Büchler et al. 6 conclude that successive quantum phase slip (QPS) events can be coherent. Here, we demonstrate that, if it exists, coherent QPS is the exact dual to Josephson tunnelling. A narrow nanowire should act as a QPS junction that shows kinetic capacitance, a plasma resonance and current plateaus of interest for nanoelectronic applications. We suggest feasible experiments to unequivocally confirm the existence for coherent QPS.Phase slip in a thin superconducting wire occurs on the scale of the superconducting coherence length. Phase slip by thermal activation 1 is observed as a resistive tail below the critical temperature. In wires with diameter below 10 nm and very high resistance, the energy barrier is small enough that phase slip by quantum tunnelling can be expected 2,3 . Wires of Mo-Ge deposited on suspended carbon nanotubes have been studied [3][4][5] , and the results are in reasonable agreement with microscopic calculations of phase-slip rates 7,8 . All experiments consisted of passing a small d.c. current through the sample and measuring the voltage. As each phase-slip event in the presence of a current I releases an energy IΦ 0 , where Φ 0 = h/2e is the flux quantum, with h the Planck constant and e the electron charge, such measurements are dissipative. Unambiguous experimental evidence of QPS is still absent. It has been concluded 5 that results can be described by thermally activated phase slip for wires with larger cross-section, and as mesoscopic diffusive normal-metal conductance for the weaker wires. The theoretical analysis is complicated by the fact that the behaviour of the bosonic superfluid may be overshadowed by the fermionic effects of localization and interaction. The superconducting energy gap in the wire may be suppressed and quasiparticles may be generated. However, we are not aware of any reason that would forbid QPS to be a physical reality. We thus assume that coherent QPS may take place, that it is characterized by a transition amplitude E S /2 and that no quasiparticles are present (E S < Δ, Δ being the superconducting energy gap). On the The diamond-shaped symbol in the QPS qubit circuit represents the quantum phase-slip process. The capacitive energy is E = E C (n − n g ) 2 and the inductivebasis of Wentzel-Kramers-Brillouin (WKB)-type estimates 3 and microscopic calculations 7 , we assume that the transition amplitude for QPS in practical superconducting nanowires of 1 μm length can be as high as E S /h = 100 GHz. Wires in which significant QPS occurs have large kinetic inductance L and smal...

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confidence: 74%

Superconducting nanowires as quantum phase-slip junctions

2006

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“…In this case the capacitance C across the Josephson junction is very small and at low temperatures T < 0.1K the behaviour of the SQUID is nonclassical [22] in the sense that the Coulomb charging energy for a Cooper pair of charge 2e,…”

Section: Mesoscopic Squid Ringmentioning

confidence: 99%

Electron interference in mesoscopic devices in the presence of nonclassical electromagnetic fields

Tsomokos

Chong

Vourdas

2005

J. Opt. B: Quantum Semiclass. Opt.

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Abstract. The interaction of mesoscopic interference devices with nonclassical electromagnetic fields is studied. The external quantum fields induce a phase factor on the electric charges. This phase factor, which is a generalization of the standard Aharonov-Bohm phase factor, is in the case of nonclassical electromagnetic fields a quantum mechanical operator. Its expectation value depends on the density matrix describing the nonclassical photons and determines the interference. Several examples are discussed, which show that the quantum noise of the nonclassical photons destroys slightly the electron interference fringes. An interesting application arises in the context of distant electron interference devices, irradiated with entangled photons. In this case the interfering electrons in the two devices become entangled. The same ideas are applied in the context of SQUID rings irradiated with nonclassical electromagnetic fields. It is shown that the statistics of the Cooper pairs tunneling through the Josephson junction depend on the statistics of the photons.

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“…2 (b)], it gives rise to the relaxation out of the eigenspace to lower energy states (this effect cannot be described by the LandauZener-type transitions). At sufficiently low temperatures compared with the superconducting gap ∆ S , the quasi-particle tunneling rate Γ qp is exponentially small [28],…”

Section: Discussionmentioning

confidence: 99%

Geometric quantum computation on solid-state qubits

Choi

2003

J. Phys.: Condens. Matter

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Geometric quantum computation is a scheme to use non-Abelian Holonomic operations rather than the conventional dynamic operations to manipulate quantum states for quantum information processing. Here we propose a geometric quantum computation scheme which can be realized with current technology on nanoscale Josephson-junction networks, known as a promising candidate for solid-state quantum computer.

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Quantum coherent effects, phase transitions, and the dissipative dynamics of ultra small tunnel junctions

Cited by 862 publications

References 163 publications

Superconducting nanowires as quantum phase-slip junctions

Superconducting nanowires as quantum phase-slip junctions

Electron interference in mesoscopic devices in the presence of nonclassical electromagnetic fields

Geometric quantum computation on solid-state qubits

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