  Quantum computation promises an exponential speedup of certain classes of
classical calculations through the preparation and manipulation of entangled
quantum states. So far most molecular simulations on quantum computers,
however, have been limited to small numbers of particles. Here we prepare a
highly entangled state on a 53-qubit IBM quantum computer, representing 53
particles, which reveals the formation of an exciton condensate of photon
particles and holes. While elusive for more than 50 years, such condensates
were recently achieved for electron-hole pairs in graphene bilayers and metal
chalcogenides. Our result with a photon condensate has the potential to further
the exploration of this new form of condensate that may play a significant role
in realizing efficient room-temperature energy transport.
