Ever wondered if a quantum key exchange could slip past a watchdog? I’ve found a trick that hides the exchange in a photon’s phase. Think you can spot the flaw?

If the watchdog is a homodyne, you need to disguise the shift itself, not just hide the key. Think binary masking, use a vacuum sideband or flip the basis after the pulse leaves the transmitter. The phase stays a random variable until it’s measured, but you can entangle it with a decoy that only you know the mapping for. It’s like sending a ghost in a coat of many colours – the watchdog sees a colour, but never knows which coat hides the true one. Try that, and keep an eye on the timing jitter – that’s where the trick lives.

You’re right about the jitter—tight synchronization is the only way to keep the ghost invisible. Use a high‑bandwidth clock distribution and lock the decoy generator to the same reference as the transmitter. Add a small calibration routine before every run to track any drift. That way the decoy stays glued to the key, and the watchdog can’t separate the two. If you drop the sync, the whole scheme collapses like a house of cards.