Related Experiment Video
Updated: Apr 19, 2026
12:57
Resonance Fluorescence of an InGaAs Quantum Dot in a Planar Cavity Using Orthogonal Excitation and Detection
Published on: October 13, 2017
9.7K
Spin-relaxation anisotropy in a GaAs quantum dot
P Scarlino1, E Kawakami1, P Stano2
1Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, Netherlands.
Physical Review Letters
|January 3, 2015
Summary
Electron spin relaxation time in GaAs quantum dots exhibits 180° periodicity with in-plane magnetic field orientation. Elliptical potentials cause deviations from predicted extrema, revealing opposite signs for Rashba and Dresselhaus constants.
Area of Science:
- Quantum dots
- Spintronics
- Semiconductor physics
Background:
- Electron spin relaxation is crucial for quantum computing applications.
- Spin-orbit coupling, including Rashba and Dresselhaus effects, influences spin dynamics in quantum dots.
- Understanding these effects is key to controlling spin states.
Purpose of the Study:
- To investigate the spin-relaxation time (T1) periodicity in a GaAs quantum dot.
- To explore the influence of in-plane magnetic field orientation on T1.
- To determine the interplay of spin-orbit coupling contributions and dot geometry.
Main Methods:
- Measurement of electron spin-relaxation time (T1) in a GaAs quantum dot.
- Rotation of an in-plane magnetic field (3 T) to study angular dependence.
- Analysis of T1 periodicity and extrema positions.
Main Results:
- Observed 180° periodicity in T1 with magnetic field orientation.
- Deviations in extrema positions from predictions for circular dots.
- T1 varied over an order of magnitude, reaching ~80 ms at optimal angles.
- Inferred opposite signs for Rashba and Dresselhaus constants.
Conclusions:
- Elliptical quantum dot potential explains deviations from circular dot predictions.
- The findings provide insights into spin dynamics and control in semiconductor quantum dots.
- The results suggest a method for determining the relative signs of spin-orbit coupling constants.
Related Concept Videos
01:23Atomic Nuclei: Nuclear Relaxation Processes
1.4K
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis.
1.4K
01:28Atomic Nuclei: Types of Nuclear Relaxation
1.2K
Nuclear relaxation restores the equilibrium population imbalance and can occur via spin–lattice or spin–spin mechanisms, which are first-order exponential decay processes.
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers...
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers...
1.2K
01:08Spin–Spin Coupling Constant: Overview
1.7K
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
1.7K
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
2.0K
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
2.0K
01:03Atomic Nuclei: Nuclear Spin State Overview
2.3K
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...
2.3K
01:08NMR Spectroscopy: Spin–Spin Coupling
3.9K
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved...
3.9K