Related Experiment Video
Updated: Jul 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
Effect of exchange interaction on spin dephasing in a double quantum dot
E A Laird1, J R Petta, A C Johnson
1Department of Physics, Harvard University, Cambridge, MA 02138, USA.
Physical Review Letters
|October 10, 2006
Summary
We measured spin dephasing in quantum dots, observing damped oscillations and saturation when exchange interaction matched hyperfine energy. This provides insights into spin dynamics in quantum computing architectures.
Area of Science:
- Quantum physics
- Condensed matter physics
- Quantum information science
Background:
- Understanding spin dynamics in quantum dots is crucial for developing quantum computing technologies.
- The interplay between exchange interaction and hyperfine fields significantly influences spin qubit coherence.
Purpose of the Study:
- To investigate singlet-triplet dephasing in a two-electron double quantum dot.
- To explore the effects of electrically tunable exchange interaction on spin dephasing.
- To compare experimental observations with theoretical models of hyperfine field effects.
Main Methods:
- Utilizing a two-electron double quantum dot system.
- Electrically tuning the exchange interaction strength relative to the hyperfine energy.
- Measuring singlet-triplet dephasing and spin correlator dynamics over time.
Main Results:
- Observed saturation of dephasing when exchange interaction strength is comparable to hyperfine energy.
- Detected damped oscillations in the spin correlator as a function of time.
- Found good agreement between experimental data and predictions from a quasistatic model of the hyperfine field.
Conclusions:
- The study demonstrates the significant impact of tunable exchange interaction on spin dephasing in double quantum dots.
- The observed phenomena provide a benchmark for theoretical models describing spin dynamics under hyperfine field influence.
- These findings contribute to the advancement of robust quantum information processing using semiconductor spin qubits.
Related Concept Videos
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
01:08NMR Spectroscopy: Spin–Spin Coupling
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 in...
01:03Atomic Nuclei: Nuclear Spin State Overview
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...
03:06The Pauli Exclusion Principle
The arrangement of electrons in the orbitals of an atom is called its electron configuration. We describe an electron configuration with a symbol that contains three pieces of information:
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
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...
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...