Entanglement and transport anomalies in nanowires

Abstract

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.

Towards a fullerene-based quantum computer

“…In semiconducting single-wall carbon nanotubes or peapods, we have the further possibility of using the correlations between the spin of a single propagating electron and that of a bound electron as a resource for quantum information processing. These are induced by a combination of Coulomb repulsion and Pauli exclusion [75,67]. For total S z = 0, there is an effective antiferromagnetic exchange interaction between the spins of the incident and bound electrons which induces entanglement between them.…”

Entanglement between static and flying qubits in a semiconducting carbon nanotube

“…However, if the system is prepared with the injected electron with spin up and the bound electron with spin down, which is not an eigenstate of the Hamiltonian, then the subsequent Coulomb interaction between the two electrons will give rise to a superposition state of the singlet and S z = 0 triplet. As described in [14], the asymptotic transmitted state after scattering may be determined as follows. The injected electron should be regarded as being in a broad wavepacket far away from the bound electron.…”

“…Due to the high confinement in the transverse directions, the well has discrete energy levels and in this sense is a quantum dot. The model is inspired by a similar study where a two-dimensional electron gas (2DEG) was used [14]. Incidentally, research on 2DEGs also suggests that unintentional shallow wells of the kind described could be responsible for the 0.7 anomaly in conductance experiments [15,16].…”

Plasmon mediated entanglement dynamics of distant quantum dots

“…[1] However, quantum information processing is facing many stringent challenges. These include the efficient high fidelity generation of many types of entangled states through diverse technologies like spin systems, flying photon qubits, [2] superconducting qubits, and atom field cavity quantum electro-dynamics (QED) systems. [3] Further, the fatal problem is the fragile nature of the engineered entangled states as they are prone to the decoherence threat.…”