When a light bulb observes voltage, it emits light, regardless of whether it did so a second earlier. When the light bulb's internal attributes entangle with the voltage, they lose all information of what came before.

This example is false. An incandescent light bulb has a memory: its temperature. The temperature both determines the amount of light currently emitted by the bulb, and also the electrical resistance of the filament (higher when hot), which means that even the connected electrical circuit is affected by the state of the bulb — turning on the bulb produces a high “inrush current”.

A much better example would be a LED (not an LED light bulb, which likely contains a stateful power supply circuit), which is stateless for most practical purposes. (For example, once upon a time, there was networking hardware which could be snooped optically — the activity indicator LEDs were simply connected to the data lines and therefore transmitted them as visible light. Modern equipment typically uses programmed blinking intervals instead.)