Non-dissipative drag of superflow in a two-component Bose gas

TL;DR

This paper develops a microscopic theory for non-dissipative drag in a two-component superfluid Bose gas, deriving expressions for the drag current, analyzing temperature effects, and proposing a measurement method using a Josephson-like system.

Contribution

It introduces a new microscopic theoretical framework for non-dissipative drag in two-component Bose gases and suggests an experimental setup for measuring the drag factor.

Findings

Drag current proportional to the square root of the gas parameter

Temperature reduction of drag current is small at low temperatures

Proposes a Josephson-like system to measure the drag factor

Abstract

A microscopic theory of a non-dissipative drag in a two-component superfluid Bose gas is developed. The expression for the drag current in the system with the components of different atomic masses, densities and scattering lengths is derived. It is shown that the drag current is proportional to the square root of the gas parameter. The temperature dependence of the drag current is studied and it is shown that at temperature of order or smaller than the interaction energy the temperature reduction of the drag current is rather small. A possible way of measuring the drag factor is proposed. A toroidal system with the drag component confined in two half-ring wells separated by two Josephson barriers is considered. Under certain condition such a system can be treated as a Bose-Einstein counterpart of the Josephson charge qubit in an external magnetic field. It is shown that the measurement of the difference of number of atoms in two wells under a controlled evolution of the state of the qubit allows to determine the drag factor.