Equation 15 · Part 1 · The Corner of the Equivalence Principle No Experiment Has Touched
Symbol eta_cl
What this part means
the these bound a combination of.
Its job in the formula
etl is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol eta_cl→Article meaning
Where the article explains it
Because rubidium and potassium differ in composition rather than internal quantum state, these bound a combination of and , not the coherence or entanglement pieces.
The passage around this formula
…same collaboration’s improved 2020 apparatus tightened that to η(Rb,K) = (−1.9 ± 3.2) × 10⁻⁷ [ 6 ] . Because rubidium and potassium differ in composition rather than internal quantum state, these bound a combination of and , not the coherence or entanglement pieces. Peter Asenbaum and colleagues pushed a single-species version of the same idea further, interfering two isotopes of rubidium in a ten-metre atomic fountain to reach η = [1.6 ± 1.8 (stat) ± 3.4 (sys)] × 10⁻¹² — three orders of…
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Sources cited in the surrounding passage
- [5] Quantum Test of the Universality of Free Fall ↗
- [6] Quantum test of the Universality of Free Fall using rubidium and potassium ↗
- [4] Atom-Interferometric Test of the Equivalence Principle at the 10⁻¹² Level ↗
- [7] Quantum test of the equivalence principle for atoms in superpositions of internal energy eigenstates ↗
- [10] Observation of a gravitational Aharonov-Bohm effect ↗
These citations provide research context; check each source for the exact claim it supports.