Related Experiment Video
Updated: Feb 25, 2026
11:21
Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
Published on: March 30, 2017
7.9K
Sign Flip in the Casimir Force for Interacting Fermion Systems
Antonino Flachi1,2, Muneto Nitta1,2, Satoshi Takada3
1Department of Physics, Keio University, 4-1-1 Hiyoshi, Kanagawa 223-8521, Japan.
Physical Review Letters
|August 5, 2017
Summary
This study explores quantum vacuum energy in finite fermionic chains. The Casimir force unexpectedly shifts from attractive to repulsive due to boundary conditions and condensate interactions.
Area of Science:
- Condensed Matter Physics
- Quantum Field Theory
- Nanotechnology
Background:
- Fermionic systems exhibit quantum vacuum energy, influencing physical phenomena.
- Boundary conditions significantly alter quantum effects in confined systems.
- Condensation processes can modify vacuum energy contributions.
Purpose of the Study:
- Investigate the impact of boundary conditions on quantum vacuum energy in finite fermionic chains.
- Analyze the resulting Casimir force behavior under these conditions.
- Understand the interplay between fermionic interactions, condensation, and vacuum energy.
Main Methods:
- Utilized a self-consistent method for theoretical analysis.
- Modeled a finite-length fermionic chain with interacting fermions.
- Applied specific boundary conditions to the fermionic system.
Main Results:
- Observed nontrivial behavior in the quantum vacuum energy.
- The Casimir force exhibited a switch from an attractive to a repulsive regime.
- Identified competition between attractive fermionic Casimir effect and repulsive condensate contribution.
Conclusions:
- Boundary conditions in finite fermionic chains lead to significant alterations in quantum vacuum energy.
- The Casimir force can transition from attractive to repulsive, driven by condensate effects.
- This finding has implications for understanding Casimir forces in nanoscopic systems.
Related Concept Videos
03:06The Pauli Exclusion Principle
59.9K
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:
59.9K
02:42Valence Bond Theory
11.4K
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...
11.4K
01:12Fermi Level Dynamics
829
The vacuum level denotes the energy threshold required for an electron to escape from a material surface. It is usually positioned above the conduction band of a semiconductor and acts as a benchmark for comparing electron energies within various materials.
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
829
01:17Spin–Spin Coupling: One-Bond Coupling
1.5K
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,...
1.5K
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
1.8K
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...
1.8K
01:22Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
1.6K
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 involved orbitals. 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 involved orbitals. The...
1.6K