Josephson current via spin and orbital states of a tunable double quantum dot

Debbarma, Rousan; Aspegren, Markus; Boström, Florinda Viñas; Lehmann, Sebastian; Dick, Kimberly A.; Thelander, Claes

doi:10.1103/physrevb.106.l180507

Cited by 9 publications

(4 citation statements)

References 35 publications

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“…1. In this case, the wire could consist either of a simple metal, or a lightly doped or gate tuned semiconductor (such as InAs [51,52]), with a single active and largely uncorrelated band. For the helical magnet, it is preferable to use a material with a short spiral wave length (λ ∼ 10 nm), low magnon energy and large spin length, such as MnGe, MnSi or NiI 2 [53,54].…”

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confidence: 99%

Light-induced topological magnons in two-dimensional van der Waals magnets

et al. 2020

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Driving a two-dimensional Mott insulator with circularly polarized light breaks time-reversal and inversion symmetry, which induces an optically-tunable synthetic scalar spin chirality interaction in the effective low-energy spin Hamiltonian. Here, we show that this mechanism can stabilize topological magnon excitations in honeycomb ferromagnets and in optical lattices. We find that the irradiated quantum magnet is described by a Haldane model for magnons that hosts topologically-protected edge modes. We study the evolution of the magnon spectrum in the Floquet regime and via time propagation of the magnon Hamiltonian for a slowly varying pulse envelope. Compared to similar but conceptually distinct driving schemes based on the Aharanov-Casher effect, the dimensionless light-matter coupling parameter \lambda = eEa/\hbar\omegaλ=eEa/ℏω at fixed electric field strength is enhanced by a factor \sim 10^5∼105. This increase of the coupling parameter allows to induce a topological gap of the order of \Delta \approx 2Δ≈2 meV with realistic laser pulses, bringing an experimental realization of light-induced topological magnon edge states within reach.

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confidence: 99%

Light-induced topological magnons in two-dimensional van der Waals magnets

et al. 2020

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“…[48] are replaced by the superconductor connecting the DQDs, their system is exactly the one studied here. In some previous work, DQDs has been proposed to be inserted between conventional superconductor leads to generate spin-correlated electron pairs, and to control the Josephson current and its critical one [40,41,43,44,49]. Our studies show that in this MNWs-DQDs-MNWs, the period, magnitude, and the directions of the Josephson current can be effectively adjusted with the help of dots' energy levels, overlap amplitude between the MBSs, as well as the magnetic flux through the loop.…”

Section: Of 11mentioning

confidence: 72%

“…Since the MBSs often emerge with the help of spin-orbit interaction, strong magnetic field or magnetic materials, they also play an important role in the research field of spintronics [31]. In recent years, some works have been devoted to the study of Josephson current through a QD connected to two semiconductor nanowires hosting MBSs (MNWs) [32][33][34][35][36], which are stimulated by the interesting results found in various system composed of QDs connected to superconductors with normal phase [37][38][39][40][41][42][43][44][45][46]. It was shown that the Josephson current driven by the topological phase difference is quite stronger than that by normal phase difference, and the bent angle formed by the two MNWs as well as the magnetic fields in the QD will significantly suppress the Josephson current [32,33].…”

Section: Of 11mentioning

confidence: 99%

Josephson Diode Effect in Parallel-Coupled Double Quantum Dots Connected to Majorana Nanowires

Gao,

Jiang,

Chi

et al. 2024

Preprint

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We study theoretically the Josephson diode effect (JDE) realized in a system composed of parallel-coupled double quantum dots (DQDs) sandwiched between two semiconductor nanowires deposited on an s-wave superconductor surface. Due to the combined effects of the proximity-caused superconductivity, strong Rashba spin-orbit interaction and Zeeman splitting inside the nanowires, a pair of Majorana bound states (MBSs) may possibly emerge at opposite ends of each nanowire. Different phase factors arisen from the superconductor substrate can be generated in the coupling amplitudes between the DQDs and MBSs prepared at the left and right nanowires, and will result in the Josephson current. We find that the critical Josephson currents in positive and negative directions are different from each other in amplitude within an oscillation period with respective to the magnetic flux penetrating through the system, a phenomenon known as the JDE. It arises from the quantum interference effect in this double-path device, and can hardly occur in system of one QD coupled to MBSs. Our results also show that the diode efficiency can reach up to 50%, and depends on the overlap amplitude between the MBSs and the energy levels of the DQDs adjustable by gate voltages. The present model is realizable within current nanofabitication technologies and may find practical use in interdisciplinary field of Majorana and Josephson physics.

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“…For example, Andreev bound states (ABSs) are formed by superposition of the Cooper pair and QD states and become the main contribution to the Josephson current. Therefore, the Josephson effect in the superconductor-QD-superconductor structures can be controlled by changing the dot size, shape, or materials in addition to those conventional means [13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Tunable Josephson Current through a Semiconductor Quantum Dot Hybridized to Majorana Trijunction

Gao,

Zhang

2023

Coatings

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We investigate theoretically the Josephson current through one semiconductor quantum dot (QD) coupled to triple nanowires (junctions) with Majorana bound states (MBSs) prepared at their ends. We find that not only the strength but also the period of the Josephson current flowing between the left and right Josephson junctions via the dot can be fully controlled in terms of the third junction side-coupled to the QD. When the phase factor is zero in the third junction, which acts as a current regulator, the Josephson current is a 2π-period function of the difference in phases of the left and right junctions. Now, the magnitude of the current is suppressed by hybridization between the QD and the regulator junction. The period of the current becomes 4π under the condition of nonzero phase factor in the regular junction, and thus either the magnitude or the sign (flow direction) of the current can be controlled in this trijunction device. This is difficult to realize in the usual tow-terminal structure. It is also found that the direct overlap between the MBSs in the regulator junction generally enhances the current’s amplitude, but those in the left and right Majorana junctions suppress the current. The above results are explained with the help of the device’s energy diagram and the current carrying density of states (CCDOS) and might be applied for adjusting the current density in the superconducting coated conductors technologies.

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Josephson current via spin and orbital states of a tunable double quantum dot

Cited by 9 publications

References 35 publications

Light-induced topological magnons in two-dimensional van der Waals magnets

Light-induced topological magnons in two-dimensional van der Waals magnets

Josephson Diode Effect in Parallel-Coupled Double Quantum Dots Connected to Majorana Nanowires

Tunable Josephson Current through a Semiconductor Quantum Dot Hybridized to Majorana Trijunction

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