# Physicists create fractional fermi sea

> Quantum physicists engineer a hidden order in ultracold atoms.
- Title: Physicists create fractional fermi sea · ScienceDaily
- Summary: Quantum physicists engineer a hidden order in ultracold atoms. Physicists created a fractional fermi sea, a highly excited quantum state with hidden order…
- Keywords: fractional fermi sea, ultracold cesium atoms, quantum physics, quantum simulation, physical review letters, one-dimensional system, fermions, quasiparticles, super fermions, science, Physicists, create
- Source: ScienceDaily — https://sciencedaily.com/releases/2026/10/261018084644.htm
- Read time: 1 min
- Topics: fractional fermi sea, ultracold cesium atoms, quantum physics, quantum simulation, physical review letters, one-dimensional system, fermions, quasiparticles, super fermions, science
## New quantum state discovered
Physicists created a fractional fermi sea, a highly excited quantum state with hidden order that defies traditional particle organization rules.

> Fermions stack neatly into available energy states to form the Fermi sea
## Ultracold cesium atoms
Ultracold cesium atoms were cycled between repulsive and attractive interactions to form a hidden ordered state.
## Fractional fermi sea definition
The fractional fermi sea appears to obey a modified rule for quantum state occupation, challenging established quantum theories.
## Hidden order despite energy
Particles maintain organization even when driven far from equilibrium, revealing distinctive mathematical patterns.
## Friedel oscillations
The system shows pronounced ripples called Friedel oscillations, wave-like variations in quantum particle interactions.
## Correlation patterns
Particle correlations weaken with distance in unusual patterns, even with weak repulsive interactions.
## Tomonaga-Luttinger theory
The findings differ from predictions of Tomonaga-Luttinger liquid theory for one-dimensional quantum systems.
## Quasiparticles
The system may produce new quasiparticles that scientists call potential super-Fermions.

> We are not yet sure how we should name these new quasiparticles perhaps super fermions
## Quantum simulation
Quantum simulation allows scientists to explore quantum states beyond traditional equilibrium paradigms.
## Theoretical framework
The discovery establishes a theoretical framework for fractional fermi seas with experimental follow-up underway.
## Key takeaway

Physicists created a fractional fermi sea, a highly excited quantum state with hidden order that defies traditional particle organization rules.