  Among the theoretically predicted two-dimensional topological insulators,
InAs/GaSb double quantum wells (DQWs) have a unique double-layered structure
with electron and hole gases separated in two layers, which enables tuning of
the band alignment via electric and magnetic fields. However, the rich
trivial-topological phase diagram has yet to be experimentally explored. We
present an in situ and continuous tuning between the trivial and topological
insulating phases in InAs/GaSb DQWs through electrical dual-gating.
Furthermore, we show that an in-plane magnetic field shifts the electron and
hole bands relatively to each other in momentum space, functioning as a
powerful tool to discriminate between the topologically distinct states.
