Cold Atom Qubits

TL;DR

This paper explores a cold-atom superfluid qubit system based on Bose-Einstein condensate currents in a ring with a Josephson barrier, detailing its theoretical foundation, initialization, manipulation, and potential for coupling and measurement.

Contribution

It introduces a novel macroscopic qubit design using BEC ring currents and demonstrates how to initialize, manipulate, and couple these qubits with existing laser-trapping techniques.

Findings

Identification of metastable current states forming a qubit

Feasibility of initializing and manipulating the qubit with current technology

Proposed mechanisms for coupling and measuring multiple qubits

Abstract

We discuss a laser-trapped cold-atom superfluid qubit system. Each qubit is proposed as a macroscopic two-state system based on a set of Bose-Einstein condensate (BEC) currents circulating in a ring, cut with a Josephson barrier. We review the effective low energy description of a single BEC ring. In particular, it is demonstrated that such system has a set of metastable current states which, for certain range of parameters, form an effective two-state system, or a qubit. We show how this qubit can be initialized and manipulated with currently available laser-trapping techniques. We also discuss mechanisms of coupling several such ring qubits as well as measuring individual qubit-ring systems.