Related Experiment Video
Updated: May 4, 2026
08:28
Single-molecule Manipulation of G-quadruplexes by Magnetic Tweezers
Published on: September 19, 2017
7.6K
Triplet-singlet spin relaxation via nuclei in a double quantum dot
A C Johnson1, J R Petta, J M Taylor
1Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Nature
|June 10, 2005
Summary
Electron spin memory loss in quantum dots is primarily due to nuclear interactions. Applying a small magnetic field significantly slows this spin relaxation, crucial for quantum computing.
Area of Science:
- Quantum Physics
- Condensed Matter Physics
- Spintronics
Background:
- Electron spin orientation is lost over time due to relaxation mechanisms.
- Previous studies focused on spin-orbit coupling or nuclear spin effects in specific split states.
Purpose of the Study:
- To investigate electron spin relaxation for arbitrary spin state splittings.
- To understand the dominant mechanisms of spin relaxation in confined electrons.
Main Methods:
- Utilized an isolated Gallium Arsenide (GaAs) double quantum dot.
- Employed direct time-domain measurements to study spin relaxation.
- Varied magnetic field strengths to observe effects on spin flips.
Main Results:
- Electron spin flips are predominantly driven by nuclear interactions.
- A magnetic field of a few millitesla dramatically slows spin relaxation by several orders of magnitude.
- Observed spin relaxation for arbitrary spin state splittings.
Conclusions:
- Nuclear interactions are the primary cause of electron spin relaxation in this system.
- Low magnetic fields are effective in preserving electron spin memory.
- Findings have significant implications for developing robust spin-based quantum information processing.
More Related Videos
Related Concept Videos
01:23Atomic Nuclei: Nuclear Relaxation Processes
1.1K
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.
1.1K
01:08Spin–Spin Coupling Constant: Overview
1.2K
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...
1.2K
01:17Spin–Spin Coupling: One-Bond Coupling
1.2K
Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...
1.2K
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
1.5K
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...
1.5K
01:22Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
1.3K
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive.
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the...
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the...
1.3K
01:28Atomic Nuclei: Types of Nuclear Relaxation
1.1K
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...
1.1K