Measurement-induced dynamics and stabilization of spinor-condensate domain walls

Weakly measuring many-body systems and allowing for feedback in real time can simultaneously create and measure new phenomena in quantum systems. We theoretically study the dynamics of a continuously measured two-component Bose-Einstein condensate (BEC) potentially containing a domain wall and focus on the tradeoff between usable information obtained from measurement and quantum back-action. Each weakly measured system yields a measurement record from which we extract real-time dynamics of the domain wall. We show that quantum back-action due to measurement causes two primary effects: domain-wall diffusion and overall heating. The system dynamics and signal-to-noise ratio depend on the choice of measurement observable. We propose a feedback protocol to dynamically create a stable domain wall in the regime where domain walls are unstable, giving a prototype example of Hamiltonian engineering using measurement and feedback.

Measurement-induced dynamics and stabilization of spinor-condensate domain walls; H. M. Hurst and I. B. Spielman; Phys. Rev. A 99 053612 (2019). doi:10.1103/PhysRevA.99.053612