  Hawking radiation is one of the quantum features of a black hole that can be
understood as a quantum tunneling across the event horizon of the black hole,
but it is quite difficult to directly observe the Hawking radiation of an
astrophysical black hole. Here, we report a fermionic lattice-model-type
realization of an analogue black hole by using a chain of 10 superconducting
transmon qubits with interactions mediated by 9 transmon-type tunable couplers.
The quantum walks of quasi-particle in the curved spacetime reflect the
gravitational effect near the black hole, resulting in the behaviour of
stimulated Hawking radiation, which is verified by the state tomography
measurement of all 7 qubits outside the horizon. In addition, the dynamics of
entanglement in the curved spacetime is directly measured. Our results would
stimulate more interests to explore the related features of black holes using
the programmable superconducting processor with tunable couplers.
