  Electromagnetic waves are ideal candidates for transmitting information in a
quantum network as they can be routed rapidly and efficiently between locations
using optical fibers or microwave cables. Yet linking quantum-enabled devices
with cables has proved difficult because most cavity or circuit quantum
electrodynamics (cQED) systems used in quantum information processing can only
absorb and emit signals with a specific frequency and temporal envelope. Here
we show that the temporal and spectral content of microwave-frequency
electromagnetic signals can be arbitrarily manipulated with a flexible aluminum
drumhead embedded in a microwave circuit. The aluminum drumhead simultaneously
forms a mechanical oscillator and a tunable capacitor. This device offers a way
to build quantum microwave networks using separate and otherwise mismatched
components. Furthermore, it will enable the preparation of non-classical states
of motion by capturing non-classical microwave signals prepared by the most
coherent circuit QED systems.
