Quantum Coherence of the Ground State of a Mesoscopic Ring

Cedraschi, Pascal; Büttiker, Μ.

doi:10.1006/aphy.2001.6116

Cited by 58 publications

(68 citation statements)

References 33 publications

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“…A dissipative resonant-level systems in equilibrium coupled to several leads maps onto the anisotropic one-channel Kondo model 8,10,11 where the dimensionless transverse Kondo coupling g (e)…”

Section: A Dissipative Resonant Level Modelmentioning

confidence: 99%

“…8,10,11. ) to biological systems 45 , (ii) two interacting fermion baths, in particular two Fractional Quantum Hall Edge (FQHE) 46 leads, or the "chiral Luttinger liquids" where electrons on the edge of a 2D fractional quantum Hall system show one-dimensional chiral Luttinger liquid behaviors with only one species of electrons (left or right movers), (iii) two interacting Luttinger-liquid leads subject to an Ohmic dissipative environment.…”

Section: Introductionmentioning

confidence: 98%

“…Through similar bosonization and refermionization procedures as in equilibrium, our model is mapped onto an anisotropic Kondo model 7,8,10,11 with the effective (Fermi-liquid) left (L) and right lead (R) 62 (see Appendix A for details):…”

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confidence: 99%

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Nonequilibrium quantum transport through a dissipative resonant level

Chung¹,

Hur

Finkelstein

et al. 2013

Phys. Rev. B

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The resonant-level model represents a paradigmatic quantum system which serves as a basis for many other quantum impurity models. We provide a comprehensive analysis of the non-equilibrium transport near a quantum phase transition in a spinless dissipative resonant-level model, extending earlier work [Phys. Rev. Lett. 102, 216803 (2009)]. A detailed derivation of a rigorous mapping of our system onto an effective Kondo model is presented. A controlled energy-dependent renormalization group approach is applied to compute the non-equilibrium current in the presence of a finite bias voltage V . In the linear response regime V → 0, the system exhibits as a function of the dissipative strength a localized-delocalized quantum transition of the Kosterlitz-Thouless (KT) type. We address fundamental issues of the non-equilibrium transport near the quantum phase transition: Does the bias voltage play the same role as temperature to smear out the transition? What is the scaling of the non-equilibrium conductance near the transition? At finite temperatures, we show that the conductance follows the equilibrium scaling for V < T , while it obeys a distinct non-equilibrium profile for V > T . We furthermore provide new signatures of the transition in the finite-frequency current noise and AC conductance via a recently developed functional renormalization group (FRG) approach. The generalization of our analysis to non-equilibrium transport through a resonant level coupled to two chiral Luttinger-liquid leads, generated by fractional quantum Hall edge states, is discussed. Our work on the dissipative resonant level has direct relevance to experiments on a quantum dot coupled to a resistive environment, such as H. Mebrahtu et al., Nature 488, 61, (2012).

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Section: A Dissipative Resonant Level Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

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Nonequilibrium quantum transport through a dissipative resonant level

Chung¹,

Hur

Finkelstein

et al. 2013

Phys. Rev. B

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“…There are two important modes of AB oscillations in double-barrier nanoring, named X and O modes. 22 The ground state entanglement with environment 23,24 and the persistent current oscillations 24,25 are also widely studied. To a certain extent, such a system can be viewed as CQDs with a multiply connected domain.…”

Section: Introductionmentioning

confidence: 99%

Aharonov-Bohm phase operations on a double-barrier nanoring charge qubit

Wang

Zhu

2006

Phys. Rev. B

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We present a scheme for charge qubit implementation in a double-barrier nanoring. The logical states of the qubit are encoded in the spatial wavefunctions of the two lowest energy states of the system. The Aharonov-Bohm phase introduced by magnetic flux, instead of tunable tunnelings, along with electric fields can be used for implementing the quantum gate operations. During the operations, the external fields should be switched smoothly enough to avoid the errors caused by the transition to higher-lying states. The structure and field effects on the validity of the qubit are also studied.

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“…In contrast, for α = 0.6, we show that S z flows to saturating values which deviate from 1/2 and fall drastically with the decreasing h. Moreover, S z yields a linear dependence versus h around h = 0 which indicates a fully screened moment: this is a clear signature of the Kondo effect. We have fitted the NRG curve for α = 0.6 (which is sufficiently far from α c ) with Bethe-Ansatz results applying to the Kondo realm 13,14 . The dependence of S z on h at various α for ∆ = 0.01 and ω c = 1 is displayed in Fig.…”

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confidence: 99%

Hidden Caldeira-Leggett Dissipation in a Bose-Fermi Kondo Model

Hur

Hofstetter

2005

Phys. Rev. Lett.

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We show that the Bose-Fermi Kondo model (BFKM), which may find applicability both to certain dissipative mesoscopic qubit devices and to heavy fermion systems described by the Kondo lattice model, can be mapped exactly onto the Caldeira-Leggett model. This mapping requires an ohmic bosonic bath and an Ising-type coupling between the latter and the impurity spin. This allows us to conclude unambiguously that there is an emergent Kosterlitz-Thouless quantum phase transition in the BFKM with an ohmic bosonic bath. By applying a bosonic numerical renormalization group approach, we thoroughly probe physical quantities close to the quantum phase transition.PACS numbers: 71.27.+a, 72.15.Qm, 75.20.Hr, 05.10.Cc The Bose-Fermi Kondo model (BFKM) (or equivalently the spin-boson-fermion model), originally introduced by Si and coworkers 1 and by Sengupta 2 to describe peculiar quantum critical behaviors in heavyfermion Kondo lattice systems 3 , involves a single impurity spin being coupled both to a bosonic bath and to a fermionic bath. Resulting from the nontrivial competition between these distinct baths, a rich phase diagram is known to emerge from this model (See, e.g., Refs. 4 and 5). More generally, a great interest is currently devoted to the understanding of the Kondo entanglement breakdown mechanism due to the presence of extra (here, bosonic) quantum fluctuations resulting in striking quantum phase transitions 6 . In this Letter, we revisit the case where the impurity spin S = 1/2 is coupled to an ohmic bosonic bath with a continuum spectrum -ohmic means that the bosonic correlation function in time t decays as 1/t 2 -through an Ising coupling. The anisotropic Hamiltonian under consideration thus takes the form:where h is a magnetic field, Ψ σ (x) and Φ represent the fermionic and bosonic fields; v b is the velocity of the bosons and K −1 b = 0 the typical coupling between the bosons and the impurity spin; Recall that K −1 b = 0 means no coupling between the impurity spin and the bosonic environment. In Eq. (2), v f is the Fermi velocity. Without loss of generality, the one-dimensional character of the Hamiltonian H sf can be viewed as a result of the point-like character of the impurity and the rotational symmetry. Besides, we omit the Ising part of the Kondo coupling J z due to its minor effect (see the last page).Our interest in the model (1-3) is also motivated by the fact that this model may be realized in mesoscopic dissipative setups involving qubits, as pointed out by one of us recently 7 . More precisely, the impurity spin can embody the two allowed charge states of a big metallic grain close to a given degeneracy point and h being proportional to the gate voltage measures deviations from this degeneracy point 8 . The conduction electrons stand for the electrons both in the metallic grain (Ψ ↓ ) and in a nearby reservoir electrode (Ψ ↑ ), and the J ⊥ (Kondo) term denotes the tunneling process of an electron from lead to grain that flips (through the raising operator S + ) the charge state of the grain, ...

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Quantum Coherence of the Ground State of a Mesoscopic Ring

Cited by 58 publications

References 33 publications

Nonequilibrium quantum transport through a dissipative resonant level

Nonequilibrium quantum transport through a dissipative resonant level

Aharonov-Bohm phase operations on a double-barrier nanoring charge qubit

Hidden Caldeira-Leggett Dissipation in a Bose-Fermi Kondo Model

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