Dynamics of interacting transport qubits

Nietner, Christian; Schaller, Gernot; Pöltl, Christina; Brandes, Tobias

doi:10.1103/physrevb.85.245431

Cited by 11 publications

(14 citation statements)

References 38 publications

(68 reference statements)

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“…Compared to this work for a single dot our TQD includes coherences between states of the two paths. Other papers [26][27][28] treat two transport paths just capacitively coupled where at some situations one of the paths blocks the transport through the other by Coulomb interaction.…”

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confidence: 99%

Channel blockade in a two-path triple-quantum-dot system

et al. 2016

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Electronic transport through a two-path triple-quantum-dot system with two source leads and one drain is studied. By separating the conductance of the two double dot paths, we are able to observe double dot and triple dot physics in transport and study the interaction between the paths. We observe channel blockade as a result of inter-channel Coulomb interaction. The experimental results are understood with the help of a theoretical model which calculates the parameters of the system, the stability regions of each state and the full dynamical transport in the triple dot resonances.PACS numbers: 73.21. La, 73.23.Hk, 73.63.Kv, 85.35.Ds, 85.35.Gv Triple quantum dots (TQDs), which have been implemented only recently [1][2][3][4], offer the possibility of analyzing new fascinating properties which are not present in double-quantum-dot systems. These new properties, to name a few, include interference phenomena between different transport channels giving rise to dark states in triangular [5][6][7][8] and linear [9] dot distributions and long distant coherent states in TQDs [9][10][11][12][13]. TQDs are, as the smallest qubit chain, a step towards more complex architectures needed in quantum computation. They allow for novel applications in the field of quantum information processing, like for example as exchange-controlled spin qubits [14,15] or as current rectifiers [1,16]. They provide as well the implementation of quantum cellular automata processes, a combination of charging and reconfiguration events in the system being a crucial process in quantum information [17,18]. Coherent electron transfer using adiabatic passage was proposed for TQDs in series [19]. Furthermore, decoherence due to charge fluctuations is reduced in a TQD-based coded qubit as it involves a decoherence free subspace [15,20]. Our system is a triangular-shaped TQD with one lead attached to each dot thus consisting of two double-dot paths. A triangular geometry is suitable for studying entanglement and effects of interference which makes it an interesting device for quantum information processing. The flexibility of this setup makes it a convenient tool for investigating the transport properties of a TQD. Transport can be measured separately and simultaneously for the two double dot paths and be compared or combined to study the whole TQDs physics on the basis of the double dots. Also, transitions from double dot resonances in one path to configurations of all three dots in resonance can be studied in transport. In contrast to former published works [4] where one source and two drain leads were used, we now use one drain and two source leads. In this configuration of two-path transport the dot connected to the drain is shared by both paths (Fig.1 (a)). The electrons from the different paths compete for the occupation of this dot. We analyze the role of interactions between the charge flowing through the two different paths by transport measurements. We observe, as a consequence of inter-channel Coulomb interaction, channel blockade in transpo...

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confidence: 99%

Channel blockade in a two-path triple-quantum-dot system

et al. 2016

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“…In our model the spin occupies, during the transport cycle, a single site with one orbital level. In this respect the model is general enough and can be relevant to electrical transport studies in parallel-coupled quantum dots 37,38 . The singlet-triplet mixing due to the SOI forms an anticrossing point in the energy spectrum.…”

Section: Discussionmentioning

confidence: 99%

Transport spectroscopy of a spin-orbit-coupled spin to a quantum dot

Giavaras

Nori

2016

Phys. Rev. B

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Electron spins in quantum dots can interact with impurity spins located in an adjacent region. This interaction may be controllable using external electric fields and it can involve an appreciable spin-orbit interaction (SOI) part affecting the expected operation of the dot spins. In this work we propose a method to quantify the interaction between a dot spin and a nearby spin by calculating the electrical current through the dot. We demonstrate some interesting regimes where the SOI can be detected, and find regimes of negative differential conductance which are sensitive to the strength of the SOI. The present study could be useful for spin-orbit qubits formed in quantum dot devices.

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“…Then, under RWA as traditionally considered, it is further changed to the JCH model [1,2,4], where the qubit-cavity interaction then becomes λ(â † nσ n − +σ n +â n ). It is widely known that Mott-insulating-to-superfluid phase transition and Mott-lobes are clearly observed in the JCH model, due to the conservation of polariton number [6][7][8][9][10][11][12][13]. And the JCH model is tightly related with the Bose-Hubbard model [4,6,7,[14][15][16].…”

Section: A Modelmentioning

confidence: 99%

“…Light and matter equally contribute to unravel this novel effect. Hence, This greatly broadens potential applications of photons to identify quantum criticality and coherence in many-body systems.The simplest paradigm to describe photon lattices with light-matter interaction is known as Jaynes-Cummings-Hubbard (JCH) model, which is composed by an array of single-mode photonic cavities, with each individually coupled to two-level system, e.g., qubit [1,2,[4][5][6][7][8][9][10][11][12][13]. The competition between the intra-site qubit-cavity coupling based on rotating-wave approximation (RWA) and inter-site photon hopping has been extensively investigated, which results in the nontrivial QPT.…”

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confidence: 99%

Influence of counter-rotating interaction on quantum phase transition in Dicke-Hubbard lattice: an extended coherent-state approach

Wang

2016

Quantum Inf Process

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We investigate the ground state behavior of the Dicke-Hubbard model including counter-rotating-terms. By generalizing an extended coherent state approach within mean-field theory, we self-consistently obtain the ground state energy and delocalized order parameter. Localization-delocalization quantum phase transition of photons is clearly observed by breaking the parity symmetry. Particularly, Mott lobes are fully suppressed, and the delocalized order parameter shows monotonic enhancement by increasing qubit-cavity coupling strength, in sharp contrast to the Dicke-Hubbard model under rotating-wave approximation. Moreover, the corresponding phase boundaries are stabilized by decreasing photon hopping strength, compared to the Rabi-Hubbard model.

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Dynamics of interacting transport qubits

Cited by 11 publications

References 38 publications

Channel blockade in a two-path triple-quantum-dot system

Channel blockade in a two-path triple-quantum-dot system

Transport spectroscopy of a spin-orbit-coupled spin to a quantum dot

Influence of counter-rotating interaction on quantum phase transition in Dicke-Hubbard lattice: an extended coherent-state approach

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