ancilla

noun3

1. •
   An auxiliary or accessory.

   • The filter achieves this two-qubit filtering effect by using two ancilla photons as probes that detect whether or not the two input photons are in the desired states. — 2009
2. •
   An ancilla bit.

   • The circuit uses a single ancilla for each stabilizer generator.
3. •
   (rare) A maid.

   • ‘And pass me that towel,’ added Ada, but the ancilla was picking up coins she had dropped in her haste […] — 1969