Generating Macroscopic Superpositions with Interacting Bose-Einstein Condensates: Multi-Mode Speed-Ups and Speed Limits

TL;DR

This paper explores how multi-mode dynamics affect the creation of macroscopic superpositions in Bose-Einstein condensates, revealing a speed limit and trade-offs between entanglement and evolution time.

Contribution

It provides a theoretical analysis of multi-mode effects on spin-cat state generation, highlighting speed limits and the impact on entanglement in Bose-Einstein condensates.

Findings

Multi-mode dynamics reduce final state entanglement.

Faster state creation involves increased multi-mode effects.

Highly entangled states are achievable despite multi-mode influences.

Abstract

We theoretically investigate the effect of multi-mode dynamics on the creation of macroscopic superposition states (spin-cat states) in Bose-Einstein condensates via one-axis twisting. A two-component Bose-Einstein condensate naturally realises an effective one-axis twisting interaction, under which an initially separable state will evolve toward a spin-cat state. However, the large evolution times necessary to realise these states is beyond the scope of current experiments. This evolution time is proportional to the degree of asymmetry in the relative scattering lengths of the system, which results in the following trade-off; faster evolution times are associated with an increase in multi-mode dynamics, and we find that generally multi-mode dynamics reduce the degree of entanglement present in the final state. However, we find that highly entangled cat-like states are still possible in the presence of significant multi-mode dynamics, and that these dynamics impose a speed-limit on the evolution such states.