Quantum Fluctuations of Vortex-Lattice State in Ultrafast Rotating Bose Gas

TL;DR

This paper investigates quantum fluctuations in an ultrafast rotating Bose gas at zero temperature, revealing the absence of condensate in the thermodynamic limit and demonstrating how quantum effects melt the vortex lattice.

Contribution

It provides a perturbative analysis of quantum fluctuations, calculates the atom density distribution, and locates the vortex-lattice spinodal point using a non-perturbative variational method.

Findings

No condensate in the thermodynamic limit due to quantum fluctuations.

Quantum fluctuations cause the melting of the vortex lattice.

Finite physical quantities are obtained despite infrared divergences.

Abstract

Quantum fluctuations in an ultrafast rotating Bose gas at zero temperature are investigated. We calculate the condensate density perturbatively to show that no condensate is present in the thermodynamic limit. The excitation from Gaussian fluctuations around the mean field solution causes infrared divergences in loop diagrams, nevertheless, in calculating the atom number density, the correlation functions and the free energy, we find the sum of the divergences in the same loop order vanishes and obtain finite physical quantities. The long-range correlation is explored and the algebraic decay exponent for the single-particle correlation function is obtained. The atom number density distribution is obtained at the one-loop level, which illustrates the quantum fluctuation effects to melt the mean field vortex-lattice. By the non-perturbative Gaussian variational method, we locate the spinodal point of the vortex-lattice state.