Weakly measuring many-body systems and allowing for feedback in real-time can simultaneously create and measure new phenomena in strongly correlated quantum systems. We study the dynamics of a continuously measured two-component Bose-Einstein condensate (BEC) potentially containing a domain wall, and focus on the trade-off between usable information obtained from measurement and quantum backaction. Each weakly measured system yields a measurement record from which we extract real-time dynamics of the domain wall. We show that quantum backaction 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 describe a feedback protocol to create and stabilize a domain wall in the regime where domain walls are unstable, giving a prototype example of Hamiltonian engineering using measurement and feedback.
Physical Review Letters
Bose-Einstein Condensate, quantum measurement, feedback