Covert Communication Over a Quantum MAC with a Helper

We study covert classical communication over a quantum multiple-access channel (MAC) with a helper.

Specifically, we consider three transmitters, where one transmitter helps the other two transmitters communicate covertly with a receiver.

We demonstrate the feasibility of achieving a positive covert rate over this channel and establish an achievable rate region.

Our result recovers as a special case known results for classical communication over classical MACs with a degraded message set, classical communication over quantum MACs, and classical communication over MACs with a helper.

To the best of our knowledge, our result is the first to achieve covert communication with positive rates over both classical and quantum MACs.