Continuous and Pulsed Quantum Zeno Effect

Continuous and pulsed quantum Zeno effects were observed using a Rb87 Bose-Einstein condensate. Oscillations between two ground hyperfine states of a magnetically trapped condensate, externally driven at a transition rate ω_R, were suppressed by destructively measuring the population in one of the states with resonant light. The suppression of the transition rate in the two-level system was quantified for pulsed measurements with a time interval δt between pulses and continuous measurements with a scattering rate γ. We observe that the continuous measurements exhibit the same suppression in the transition rate as the pulsed measurements when γδt=3.60(0.43), in agreement with the predicted value of 4. Increasing the measurement rate suppressed the transition rate down to 0.005ω_R.