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 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.

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.

scholarly journals Non-Ideal X-Gate and Z-Gate in Semiconducting Spin Qubit Implementations

Proceedings ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 53
Author(s):  
Elena Ferraro ◽  
Marco Fanciulli ◽  
Marco De Michielis
Keyword(s):  
Quantum Dot ◽  
Quantum Computation ◽  
Double Quantum ◽  
Time Interval ◽  
Effective Hamiltonian ◽  
Single Qubit ◽  
Hamiltonian Models ◽  
Double Quantum Dot ◽  
Spin Qubit ◽  
Qubit Gate

Several spin qubit architectures have been proposed, theoretically investigated and realized at least on the scale of single devices in view of quantum computation and simulation applications. We focus our study on five qubit types: quantum dot spin qubit, double quantum dot singlet-triplet qubit, double quantum dot hybrid qubit, donor qubit, quantum dot spin-donor qubit and for each one we derived a compact effective Hamiltonian. Single qubit gate fidelities when time interval error is included are compared. A realistic set of values for the error parameters of amplitude controls linked to the z and x contribution appearing in the Hamiltonian models has been used. This study provides a ranking of the gate fidelities for the different qubit architectures highlighting which one is the most robust with respect to the considered control noises.

scholarly journals Subgap Dynamics of Double Quantum Dot Coupled Between Superconducting and Normal Leads

2021 ◽  
Author(s):  
Bartłomiej Baran ◽  
Ryszard Taranko ◽  
Tadeusz Domański
Keyword(s):  
Quantum Dot ◽  
Energy Levels ◽  
Sudden Change ◽  
Time Dependent ◽  
Double Quantum ◽  
Valuable Insight ◽  
Characteristic Energy ◽  
Double Quantum Dot ◽  
In Series ◽  
External Time

Abstract Dynamical 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.

scholarly journals Large Voltage-Tunable Spin Valve Based on a Double Quantum Dot

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Patrycja Tulewicz ◽  
Kacper Wrześniewski ◽  
Szabolcs Csonka ◽  
Ireneusz Weymann
Keyword(s):  
Quantum Dot ◽  
Spin Valve ◽  
Double Quantum ◽  
Double Quantum Dot

Fano Effect in T-Shaped Double Quantum Dot Structure with Decoherence Effect

2008 ◽  
Vol 49 (3) ◽  
pp. 771-776 ◽  
Author(s):  
Gao Wen-Zhu ◽  
Gong Wei-Jiang ◽  
Zheng Yi-Song ◽  
Liu Yu ◽  
Lü Tian-Quan
Keyword(s):  
Quantum Dot ◽  
Double Quantum ◽  
Fano Effect ◽  
Double Quantum Dot ◽  
Decoherence Effect

Electron transport in T-shaped double quantum dot structure

2021 ◽  
Vol 53 (8) ◽  
Author(s):  
Mohammed A. A. Abbas ◽  
Lafy F. Al-Badry ◽  
Amin H. Al-Khursan
Keyword(s):  
Electron Transport ◽  
Quantum Dot ◽  
Double Quantum ◽  
Double Quantum Dot
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