Bringing P type and N type semiconductors together in vacuum
First of all, No, you won't detect any current...Second of all, a junction isn't formed just by bringing two semiconductors together in contact. It is a process where the two materials are heated up forming a crystal structure and thus its conductive properties
Why won't you detect any current? That's an experimental fact, what is maybe confusing you is the fact that there is no NET current in the device, but there is an inner current of 4 components which is not zero, and they cancel each other resulting no net current.
A description of the current is as follows:
(Based on the book Solid State Electronic Devices pages 195-196 )

When Putting two materials together, forming a P-N junction, we have
four components to participate in the flow. We expect diffusion of
carriers to take place, holes diffuse from the p side into the n side,
and electrons diffuse from n to p, And we have drift current to oppose
them. Since we know that no net current can flow across the junction
at equilibrium, the current due to the drift of carriers in the ℰ
field must exactly cancel the diffusion current. Furthermore, since
there can be no net buildup  of electrons or holes on either side as a
function of time, the drift and diffusion currents must cancel for
each type of carrier.