Drag Force on an Impurity below the Superfluid Critical Velocity in a Quasi-One-Dimensional Bose-Einstein Condensate

Journal Article · Fri Aug 21 00:00:00 EDT 2009 · Physical Review Letters

DOI:https://doi.org/10.1103/PHYSREVLETT.103.085302· OSTI ID:21364630

Sykes, Andrew G; Davis, Matthew J ^[1]; Roberts, David C ^[2]

---

1. University of Queensland, School of Mathematics and Physics, ARC Centre of Excellence for Quantum-Atom Optics, Brisbane 4072 (Australia)
2. Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

The existence of frictionless flow below a critical velocity for obstacles moving in a superfluid is well established in the context of the mean-field Gross-Pitaevskii theory. We calculate the next order correction due to quantum and thermal fluctuations and find a nonzero force acting on a delta-function impurity moving through a quasi-one-dimensional Bose-Einstein condensate at all subcritical velocities and at all temperatures. The force occurs due to an imbalance in the Doppler shifts of reflected quantum fluctuations from either side of the impurity. Our calculation is based on a consistent extension of Bogoliubov theory to second order in the interaction strength, and finds new analytical solutions to the Bogoliubov-de Gennes equations for a gray soliton. Our results raise questions regarding the quantum dynamics in the formation of persistent currents in superfluids.

• OSTI ID: 21364630
• Journal Information: Physical Review Letters, Vol. 103, Issue 8; Other Information: DOI: 10.1103/PhysRevLett.103.085302; (c) 2009 The American Physical Society; ISSN 0031-9007
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANALYTICAL SOLUTION
BOSE-EINSTEIN CONDENSATION
CRITICAL VELOCITY
DELTA FUNCTION
DOPPLER EFFECT
EQUATIONS
IDEAL FLOW
IMPURITIES
MEAN-FIELD THEORY
SOLITONS
SUPERFLUIDITY
FLUID FLOW
FUNCTIONS
INCOMPRESSIBLE FLOW
MATHEMATICAL SOLUTIONS
QUASI PARTICLES
STEADY FLOW
VELOCITY