  In this article, we design a quantum device to duplicate the Robins
procedure. The Robins use a unique method to determine the migratory direction.
In the procedure utilized, the important issue is the effect of the geomagnetic
field on the magnetic momentum of created radical pairs (triplet-singlet
states) dancing with a special frequency. To duplicate the same operational
procedure, the quantum sensor consisting of two coincident tripartite systems
is designed. Each system is separately excited with the entangled photons
(signal and idler) produced through nonlinearity. In a traditional tripartite
system, the microwave cavity mode can be non-classically correlated with the
optical cavity mode. In this study, however, there are two microwave cavities
modes separately affected by the entangled photons, and these modes can be
entangled. The entangled microwave photons play the same role that the
triplet-singlet state of the electrons have in the Robins operating system. It
is the key point that the quantum sensor is deigned to work with, in such a way
that the entangled microwave photons can be strongly affected by the applied
external magnetic field. In fact, it is the criterion employed by the quantum
sensor to sense the magnetic field intensity and the direction. To analyze the
system, the canonical conjugate method is introduced to determine the quantum
sensor Hamiltonian, and then the dynamics equations of motions are analytically
derived using Heisenberg-Langevin equations.
