scholarly journals Electronic Transport Through Double Quantum Dot Coupled to Majorana Bound States and Ferromagnetic Leads

2021 ◽  
Vol 8 ◽  
Author(s):  
Li-Wen Tang ◽  
Wei-Guo Mao
Keyword(s):  
Quantum Dot ◽  
Coupling Strength ◽  
Bound States ◽  
High Efficiency ◽  
Energy Levels ◽  
Electrical Current ◽  
Function Technique ◽  
Double Quantum ◽  
Majorana Bound States ◽  
Double Quantum Dot

We have studied theoretically the properties of electrical current and tunnel magnetoresistance (TMR) through a serially connected double quantum dot (DQD) sandwiched between two ferromagnetic leads by using the nonequilibrium Green’s function technique. We consider that each of the DQD couples to one mode of the Majorana bound states (MBSs) formed at the ends of a topological superconductor nanowire with spin-dependent coupling strength. By adjusting the sign of the spin polarization of dot–MBS coupling strength and the arrangement of magnetic moments of the two leads, the currents’ magnitude can be effectively enhanced or suppressed. Under some conditions, a negative TMR emerges which is useful in detection of the MBSs, a research subject currently under extensive investigations. Moreover, the amplitude of the TMR can be adjusted in a large regime by variation of several system parameters, such as direct hybridization strength between the MBSs or the dots and the positions of the dots’ energy levels. Such tunable currents and TMR may also find use in high-efficiency spintronic devices or information processes.

Conductance through a parallel-coupled double quantum dot with a side-coupled quantum dot system

2017 ◽  
Vol 31 (09) ◽  
pp. 1750095 ◽  
Author(s):  
Zelong He ◽  
Jiyuan Bai ◽  
Cheng Ma
Keyword(s):  
Quantum Dot ◽  
Coupling Strength ◽  
Fano Resonance ◽  
Numerical Results ◽  
Function Technique ◽  
Double Quantum ◽  
Double Quantum Dot ◽  
Couple Quantum ◽  
Interdot Coupling ◽  
Non Equilibrium Green’S Function

Using the non-equilibrium Green’s function technique, conductance through a parallel-coupled double quantum dot (PCDQD) with a side-coupled quantum dot system is investigated. The evolution of the conductance strongly depends on the coupling between the side-coupled quantum dot and PCDQD. Moreover, the conductance as a function of the level of side-couple quantum dot is investigated. Numerical results indicate the lineshape of Fano resonance can be modulated by adjusting the interdot coupling strength.

scholarly journals Andreev reflection in a T-shaped double quantum-dot with coupled Majorana bound states

2016 ◽  
Vol 65 (13) ◽  
pp. 137302
Author(s):  
Wang Su-Xin ◽  
Li Yu-Xian ◽  
Wang Ning ◽  
Liu Jian-Jun
Keyword(s):  
Quantum Dot ◽  
Bound States ◽  
Andreev Reflection ◽  
Double Quantum ◽  
Majorana Bound States ◽  
Double Quantum Dot

Andreev Reflection in a T-Shaped Double-Quantum-Dot Structure Induced by Majorana Bound States

2014 ◽  
Vol 83 (3) ◽  
pp. 034706 ◽  
Author(s):  
Wei-Jiang Gong ◽  
Shu-feng Zhang ◽  
Zhi-Chao Li ◽  
Guangyu Yi ◽  
Yi-Song Zheng
Keyword(s):  
Quantum Dot ◽  
Bound States ◽  
Andreev Reflection ◽  
Double Quantum ◽  
Majorana Bound States ◽  
Double Quantum Dot

scholarly journals Heat Generation by Electrical Current in a Quantum Dot Hybridized to Majorana Nanowires

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhu-Hua Wang
Keyword(s):  
Quantum Dot ◽  
Bias Voltage ◽  
Heat Generation ◽  
Bound States ◽  
Waste Heat ◽  
Electrical Current ◽  
Function Technique ◽  
Heat Current ◽  
Low Dimensional ◽  
Direct Hybridization

Heat current generated by electronic transport through a quantum dot (QD) coupled to both a phonon bath and a Majorana nanowire hosting Majorana bound states (MBSs) is theoretically studied in the framework of non-equilibrium Green’s function technique. The calculated numerical results show that electrical current can be either enhanced or suppressed by the combined influences of the phonon bath and the MBSs at certain bias voltage regimes. The enhancement and suppression of the current’s magnitude for a fixed bias voltage will be reversed due to the direct hybridization between the MBSs. The simultaneous coupling between both MBSs will amplify the function of the MBSs on the current, with the same unchanged and essential qualitative impacts. Heat generation by the electrical current can be fully adjusted by the dot–MBS coupling, direct hybridization between the MBSs, and positions of the dot level. By properly choosing the above parameters, heat generation can be suppressed even for increased electrical current, which is favorable in removing waste heat generated by electrical current flowing through low-dimensional circuits.

scholarly journals Spatial Rabi oscillations between Majorana bound states and quantum dots

2018 ◽  
Vol 9 ◽  
pp. 1527-1535
Author(s):  
Jun-Hui Zheng ◽  
Dao-Xin Yao ◽  
Zhi Wang
Keyword(s):  
Quantum Dot ◽  
Bound States ◽  
Bound State ◽  
Double Quantum ◽  
Energy Splitting ◽  
Rabi Oscillations ◽  
Andreev Bound States ◽  
Majorana Bound States ◽  
Nonlocal Quantum ◽  
Equal Amplitude

Background: A Majorana bound state is a superconducting quasiparticle that is the superposition of particle and hole with equal amplitude. We propose a verification of this amplitude equality by analyzing the spatial Rabi oscillations of the quantum states of a quantum dot that is tunneling-coupled to the Majorana bound states. Results: We find two resonant Rabi driving energies that correspond to the energy splitting due to the coupling of two spatially separated Majorana bound states. The resulting Rabi oscillating frequencies from these two different resonant driving energies are identical for the Majorana bound states, while different for ordinary Andreev bound states. We further study a double-quantum-dot setup and find a nonlocal quantum correlation between them that is mediated by two Majorana bound states. This nonlocal correlation has the signature of additional resonant driving energies. Conclusion: Our method can be used to distinguish between Majorana bound states and Andreev bound states. It also gives a precise measurement of the energy splitting between two Majorana bound states.

Investigation of silicon isolated double quantum-dot energy levels for quantum computation

2006 ◽  
Vol 83 (4-9) ◽  
pp. 1818-1822 ◽  
Author(s):  
Michael G. Tanner ◽  
David G. Hasko ◽  
David A. Williams
Keyword(s):  
Quantum Dot ◽  
Quantum Computation ◽  
Energy Levels ◽  
Double Quantum ◽  
Double Quantum Dot

scholarly journals Subgap dynamics of double quantum dot coupled between superconducting and normal leads

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
B. Baran ◽  
R. Taranko ◽  
T. Domański
Keyword(s):  
Quantum Dot ◽  
Energy Levels ◽  
Sudden Change ◽  
Time Dependent ◽  
Double Quantum ◽  
Valuable Insight ◽  
Characteristic Energy ◽  
Double Quantum Dot ◽  
In Series ◽  
External Time

AbstractDynamical processes induced by the external time-dependent fields can provide valuable insight into the characteristic energy scales of a given physical system. We investigate them here in a nanoscopic heterostructure, consisting of the double quantum dot coupled in series to the superconducting and the metallic reservoirs, analyzing its response to (i) abrupt bias voltage applied across the junction, (ii) sudden change of the energy levels, and imposed by (iii) their periodic driving. We explore subgap properties of this setup which are strictly related to the in-gap quasiparticles and discuss their signatures manifested in the time-dependent charge currents. The characteristic multi-mode oscillations, their beating patters and photon-assisted harmonics reveal a rich spectrum of dynamical features that might be important for designing the superconducting qubits.

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