Related Experiment Video
Updated: Mar 22, 2026
11:21
Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
Published on: March 30, 2017
8.0K
Quantum Kibble-Zurek Mechanism in a Spin-1 Bose-Einstein Condensate
M Anquez1, B A Robbins1, H M Bharath1
1School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Physical Review Letters
|April 30, 2016
Summary
Researchers explored quantum phase transition dynamics in a spin-1 Bose-Einstein condensate. Experimental results confirm the quantum Kibble-Zurek model by showing power-law scaling in excitation onset versus quench speed.
Area of Science:
- Quantum physics
- Condensed matter physics
- Atomic physics
Background:
- Quantum phase transitions (QPTs) represent fundamental changes in quantum systems.
- The Kibble-Zurek mechanism describes defect formation during phase transitions.
- Spin-1 Bose-Einstein condensates (BECs) offer a controllable platform for studying quantum dynamics.
Purpose of the Study:
- To investigate the dynamics of quantum phase transitions in a spin-1 ferromagnetic Bose-Einstein condensate.
- To experimentally test predictions of quantum extensions to the Kibble-Zurek mechanism.
- To explore the relationship between quench speed and excitation onset during a phase transition.
Main Methods:
- Utilized slow quenches across a quantum phase transition from polar to broken-axisymmetry phases.
- Measured the evolution of spin populations in a small spin-1 ferromagnetic Bose-Einstein condensate.
- Analyzed the temporal onset of excitations as a function of quench speed.
Main Results:
- Observed a power-law scaling between the temporal onset of excitations and the quench speed.
- The measured scaling exponent showed satisfactory agreement with analytical theory.
- Experimental results aligned with predictions from numerical simulations.
Conclusions:
- Experimental confirmation of the quantum Kibble-Zurek model was achieved.
- The study validates the application of the Kibble-Zurek mechanism to quantum phase transitions in BECs.
- Provides insights into the dynamics and defect formation during quantum quenches.
Related Concept Videos
01:03Atomic Nuclei: Nuclear Spin State Overview
2.2K
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...
2.2K
01:14Atomic Nuclei: Nuclear Spin State Population Distribution
2.6K
Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.
2.6K
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
01:17Spin–Spin Coupling: One-Bond Coupling
1.6K
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,...
1.6K
01:08Spin–Spin Coupling Constant: Overview
1.6K
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...
1.6K
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
1.9K
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...
1.9K