  We have developed a new type of magnetometer consisting of a Hybrid Quantum
Interference Device (HyQUID) that is set in a bi-stable state. We demonstrate
its operation in a latching mode that can be employed to measure small changes
in the applied flux. The device can be used to probe the flux state of a
superconducting circuit using straightforward electrical resistance
measurements, making it suitable as a simple qubit readout with low
back-action.
