Conductance anomalies and the extended Anderson model for nearly perfect quantum wires

Rejec, T.; Ramšak, A.; Jefferson, J. H.

doi:10.1103/physrevb.67.075311

Cited by 28 publications

(40 citation statements)

References 48 publications

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“…We may regard this system as an open quantum dot with Coulomb blockade precluding further electrons from being bound. Such a system can show exotic behaviour similar to the Kondo effect observed in more conventional quantum-dot systems with high confining barriers 12 and this behaviour has also been related to the conductance anomalies referred to earlier and considered previously by the present authors 13,14 and others 15 . For the two-electron case we will show that the scattering of the flying qubit from the static qubit can induce en-tanglement in a controlled fashion and may thus be regarded as a candidate for realising a general two-qubit gate and explicitly demonstrating exchange of quantum information between a static qubit and a flying qubit.…”

mentioning

confidence: 70%

“…1). As described in previous work 13,14 , the bound electron has a longrange Coulomb interaction with the propagating electron and, when combined with the well potential, gives rise to a double barrier structure which has a singlet resonance energy at approximately ǫ s ∼ ǫ b + U , where ǫ b is the energy of the lowest bound state and U = 15 meV is the Coulomb matrix element for two electrons of opposite spin occupying this state. This is also shown in Fig.…”

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confidence: 99%

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Entanglement between static and flying qubits in quantum wires

2006

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A weakly bound electron in a semiconductor quantum wire is shown to become entangled with an itinerant electron via the coulomb interaction. The degree of entanglement and its variation with energy of the injected electron, may be tuned by choice of spin and initial momentum. Full entanglement is achieved close to energies where there are spin-dependent resonances. Possible realisations of related device structures are discussed.PACS numbers: 03.67. Mn, 03.67.Pp, A major goal in the rapidly emerging field of quantum information processing is the controlled exchange of quantum information between propagating and static qubits. Purely electron systems have potential as entanglers due to strong Coulomb interactions and although charge-qubit systems suffer from short coherence times, spins in semiconductor quantum wires and dots are sufficiently long-lived for spin-qubits to be promising candidate for realizing quantum gates involving both static and propagating spins 1,2,3,4,5 . Entanglement between propagating electron pairs has been proposed using an electron beamsplitter 6 , a double-dot electron entangler exploiting the singlet ground state 7 , the exchange interaction between conduction electrons in a single dot 8,9 and the exchange interaction between electron spins in parallel surface acoustic wave channels 10 . In this letter we propose a scheme whereby a single propagating electron interacts strongly with a bound electron in a quantum wire. This differs from the quantumdot systems referred to above in several respects. Firstly, entanglement is induced between the spins of one propagating and one bound electron, rather than two propagating electrons, and this entanglement is detected directly by measuring electron spin, rather than indirectly through current-current correlations. Secondly, the entangling interaction between the propagating and bound electron in the quantum wire is enhanced compared with a quantum-dot system, giving rise to spin-dependent resonant bound states that are a consequence of the Coulomb interaction and electron antisymmetry, rather than externally imposed barriers. This allows considerable flexibility in controlling the entangling interactions via the kinetic energy of the incident electron.Consider a semiconductor quantum wire in which there is a weak confining potential which is capable of binding one, and only one, electron. Slight deviation from a perfect 1D confining potential, either accidental or deliberate, can give rise to fully bound states for electrons. When the confining potential is very weak, such as occurs with a weak symmetric bulge in an otherwise perfect wire, there is one and only one bound state 11 . Furthermore, only a single electron can be bound in this confining potential since the energy of a second electron will be in the continuum due to Coulomb repulsion. We have shown that the spin-dependent interaction between a single propagating electron and the weakly bound electron electron can induce entanglement between them, giving rise to a two-electron quant...

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Entanglement between static and flying qubits in quantum wires

2006

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“…This approximation is only valid at temperatures above the Kondo scale in this system [49], as discussed in Ref. [34]. Eq.…”

Section: Shot Noise and 07 Anomalymentioning

confidence: 99%

“…The resulting Anderson-like Hamiltonian [50] for the case of shallow well only, i.e. not quantum-dot barriers, takes the form [16,34],…”

Section: Many-body Effectsmentioning

confidence: 99%

Entanglement and transport anomalies in nanowires

Jefferson¹,

Ramšak²,

Rejec³

2008

J. Phys.: Condens. Matter

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Abstract. A shallow potential well in a near-perfect quantum wire will bind a single-electron and behave like a quantum dot, giving rise to spin-dependent resonances of propagating electrons due to Coulomb repulsion and Pauli blocking. It is shown how this may be used to generate full entanglement between static and flying spin-qubits near resonance in a two-electron system via singlet or triplet spin-filtering. In a quantum wire with many electrons, the same pairwise scattering may be used to explain conductance, thermopower and shot-noise anomalies, provided the temperature/energy scale is sufficiently high for Kondolike many-body effects to be negligible.

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“…Mostly quantum dots are considered with an internal quantum structure [15][16][17], e.g. the coupling of quantum dots to superconducting leads [18].…”

Section: Introductionmentioning

confidence: 99%

Quantum currents and pair correlation of electrons in a chain of localized dots

Morawetz

2017

Eur. Phys. J. B

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Abstract. The quantum transport of electrons in a wire of localized dots by hopping, interaction and dissipation is calculated and a representation by an equivalent RCL circuit is found. The exact solution for the electric-field induced currents allows to discuss the role of virtual currents to decay initial correlations and Bloch oscillations. The dynamical response function in random phase approximation (RPA) is calculated analytically with the help of which the static structure function and pair correlation function are determined. The pair correlation function contains a form factor from the Brillouin zone and a structure factor caused by the localized dots in the wire.

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Conductance anomalies and the extended Anderson model for nearly perfect quantum wires

Cited by 28 publications

References 48 publications

Entanglement between static and flying qubits in quantum wires

Entanglement between static and flying qubits in quantum wires

Entanglement and transport anomalies in nanowires

Quantum currents and pair correlation of electrons in a chain of localized dots

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