Large-Scale Bose-Einstein Condensation in an Atomic Gas by Applying an Electric Field
Pei-Lin You
Large-scale Bose-Einstein condensation (BEC) of cesium atoms has been observed (T=343K). The technical bottleneck of BEC is very small trapping volume (10-8cm3), which made the number of condensed atoms still stagnant (less than 107), much smaller than normal condensation (more than 1013), large-scale BEC has never been observed. In BEC experiment, scientists have applied magnetic field (used to trap atoms) and laser (used to cool atoms), but never considered applying electric field, because they think that all kinds of atoms are non-polar atoms. The breakthrough of the bottleneck lies in the application of electric field. In theory, despite 6s and 6p states of cesium are not degenerate, but Cs may be polar atom doesn't conflict with quantum mechanics because it is hydrogen-like atom. When an electric field was applied, Cs atoms become dipoles, therefore large-scale BEC can be observed. BEC experiment of cesium has been redone. From the entropy S=0, critical voltage Vc=78V. When V < Vc, S > 0; when V > Vc, S<0, phase transition occurred. When V=370V, condensates contained up to 2.71×1017 atoms, a forty percent improvement over previous results. This BEC is a second-order phase transition because entropy doesn't show discontinuity, from Wikipedia. It is also equivalent to a quantum phase transition. The permanent dipole moment (PDM) of Cs atom has been accurately measured: dCs=[1.84±0.15(stat) ±0.11 (syst)] ×10-8 e.cm. The PDM doesn't arise from the nuclear spin but arises from asymmetrical charge distribution, and it doesn't violate both time reversal and parity symmetry. The maximum induced dipole moment is dind ≤ 2.12 ×10-13e.cm, which can be ignored. BEC has three main features: BEC is macroscopic occupation of the ground state of the system; BEC is condensation in momentum space; Bose gas would undergo a phase transition. Our experiment is an ideal BEC because it conforms to the three features. BEC belongs to the condensation of quantum gas, when V > Vc, almost all Cs atoms (bosons) are in exactly the same state，according to Feynman, “the quantum physics is the same thing as the classical physics”, so our classical theory can explain BEC experiment satisfactorily. Ultra-low temperature is to make Bose gas phase transition, we used critical voltage to achieve phase transition, ultra-low temperature is no longer necessary. Five innovative formulas were first reported in the history of physics, the publication of this article marking mankind will enter a new era of polar atoms.
American Journal of Modern Physics•Jan 1, 2018•1 citation