  This paper introduces HoloBots, a mixed reality remote collaboration system
that augments holographic telepresence with synchronized mobile robots. Beyond
existing mixed reality telepresence, HoloBots lets remote users not only be
visually and spatially present, but also physically engage with local users and
their environment. HoloBots allows the users to touch, grasp, manipulate, and
interact with the remote physical environment as if they were co-located in the
same shared space. We achieve this by synchronizing holographic user motion
(Hololens 2 and Azure Kinect) with tabletop mobile robots (Sony Toio). Beyond
the existing physical telepresence, HoloBots contributes to an exploration of
broader design space, such as object actuation, virtual hand physicalization,
world-in-miniature exploration, shared tangible interfaces, embodied guidance,
and haptic communication. We evaluate our system with twelve participants by
comparing it with hologram-only and robot-only conditions. Both quantitative
and qualitative results confirm that our system significantly enhances the
level of co-presence and shared experience, compared to the other conditions.
