  Atomic arrays provide an important quantum optical platform with
photon-mediated dipoledipole interactions, which can be engineered to realize
key applications in quantum information processing. A major obstacle for such
application is the fast decay of the excited states. By controlling two-band
Bloch oscillations in an atomic array under external magnetic field, here we
show that exotic subradiance can be realized and maintained at a time scale
upto 12 orders of magnitude larger than the spontaneous decay time in atomic
arrays with the finite size. The key finding is to show a way for preventing
the wavepacket of excited states scattering into the dissipative zone inside
the free space light cone, which therefore leads to the excitation staying at a
subradiant state for extremely long decay time. We show that such operation can
be achieved by introducing a spatially linear potential from external magnetic
field in atomic arrays and then manipulating interconnected two-band Bloch
oscillations along opposite directions. Our results also point out the
possibility of controllable switching between superradiant and subradiant
states, which leads to potential applications in quantum storage.
