scholarly journals Controlling Synthetic Spin-Orbit Coupling in a Silicon Quantum Dot with Magnetic Field

2021 ◽  
Vol 15 (4) ◽  
Author(s):  
Xin Zhang ◽  
Yuan Zhou ◽  
Rui-Zi Hu ◽  
Rong-Long Ma ◽  
Ming Ni ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Quantum Dot ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Silicon Quantum Dot

scholarly journals Spin manipulation and decoherence in a quantum dot mediated by a synthetic spin-orbit coupling of broken $T$-symmetry

2021 ◽  
Author(s):  
Peihao Huang ◽  
Xuedong Hu
Keyword(s):  
Magnetic Field ◽  
Quantum Dot ◽  
Spin Relaxation ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Field Orientation ◽  
Spin Manipulation ◽  
Pure Dephasing ◽  
Spin Qubit

Abstract The electrical control of a spin qubit in a quantum dot relies on spin-orbit coupling (SOC), which could be either intrinsic to the underlying crystal lattice or heterostructure, or extrinsic via, for example, a micro-magnet. In experiments, micromagnets have been used as a synthetic SOC to enable strong coupling of a spin qubit in quantum dots with electric fields. Here we study theoretically the spin relaxation, pure dephasing, spin manipulation, and spin-photon coupling of an electron in a quantum dot due to the synthetic SOC induced spin-orbit mixing. We find qualitative difference in the spin dynamics in the presence of a synthetic SOC compared with the case of the intrinsic SOC. Specifically, spin relaxation due to the synthetic SOC and deformation potential phonon emission (or Johnson noise) shows $B_0^5$ (or $B_0$) dependence with the magnetic field, which is in contrast with the $B_0^7$ (or $B_0^3$) dependence in the case of the intrinsic SOC. Moreover, charge noise induces fast spin dephasing to the first order of the synthetic SOC, which is in sharp contrast with the negligible spin pure dephasing in the case of the intrinsic SOC. These qualitative differences are attributed to the broken time-reversal symmetry ($T$-symmetry) of the synthetic SOC. An SOC with broken $T$-symmetry (such as the synthetic SOC from a micro-magnet) eliminates the ``Van Vleck cancellation'' and causes a finite longitudinal spin-electric coupling that allows the longitudinal coupling between spin and electric field, and in turn allows spin pure dephasing. Finally, through proper choice of magnetic field orientation, the electric-dipole spin resonance via the synthetic SOC can be improved with potential applications in spin-based quantum computing.

scholarly journals Observation of spin–orbit coupling induced Weyl points in a two-electron double quantum dot

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Zoltán Scherübl ◽  
András Pályi ◽  
György Frank ◽  
István Endre Lukács ◽  
Gergő Fülöp ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Quantum Dot ◽  
Kondo Effect ◽  
Surface States ◽  
Orbit Coupling ◽  
Double Quantum ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Electronic Band ◽  
Ground State Degeneracy

Abstract Recent years have brought an explosion of activities in the research of topological aspects of condensed-matter systems. Topological phases of matter are accompanied by protected surface states or exotic degenerate excitations such as Majorana modes or Haldane’s localized spinons. Topologically protected degeneracies can, however, also appear in the bulk. An intriguing example is provided by Weyl semimetals, where topologically protected electronic band degeneracies and exotic surface states emerge even in the absence of interactions. Here we demonstrate experimentally and theoretically that Weyl degeneracies appear naturally in an interacting quantum dot system, for specific values of the external magnetic field. These magnetic Weyl points are robust against spin–orbit coupling unavoidably present in most quantum dot devices. Our transport experiments through an InAs double-dot device placed in magnetic field reveal the presence of a pair of Weyl points, exhibiting a robust ground-state degeneracy and a corresponding protected Kondo effect.

scholarly journals Spin-Orbit Coupling Effects on Transport Properties of Electronic Lieb Lattice in the Presence of Magnetic Field

2021 ◽  
Author(s):  
Elham Sadeghi ◽  
Hamed Rezania
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
Seebeck Coefficient ◽  
Temperature Dependence ◽  
Transport Properties ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Lieb Lattice ◽  
Thermal Conductivities

Abstract In this paper, the transport properties of a two-dimensional Lieb lattice that is a line-centered square lattice are investigated in the presence of magnetic field and spin-orbit coupling. Specially, we address the temperature dependence of electrical and thermal conductivities as well as Seebeck coefficient due to spin-orbit interaction. We have exploited Green’s function approach in order to study thermoelectric and transport properties of Lieb lattice in the context of Kane-Mele model Hamiltonian. The results for Seebeck coefficient show the sign of thermopower is positive in the presence of spin-orbit coupling. Also the temperature dependence of transport properties indicates that the increase of spin-orbit coupling leads to decrease thermal conductivity however the decrease of gap 1 parameter causes the reduction of thermal conductivity. There is a peak in temperature dependence of thermal conductivity for all values of magnetic fields and spin-orbit coupling strengths. Both electrical and thermal conductivities increase with increasing the temperature at low amounts of temperature due to the increasing of transition rate of charge carriers and excitation of them to the conduction bands. Also we have studied the temperature dependence of spin susceptibility of Lieb monolayer due to both spin orbit coupling and magnetic field factors in details.

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