Boiling Quantum Vacuum: Thermal Subsystems from Ground-State Entanglement

In certain special circumstances, such as in the vicinity of a black hole or uniformly accelerating frame, vacuum fluctuations appear to give rise finite-temperature environment. This effect, currently without experimental confirmation, can be interpreted manifestation quantum entanglement after tracing out modes an unobserved region. this work, we identify class experimentally accessible systems where thermal density matrices emerge from entanglement. We show that reduced lower-dimensional subsystems embedded $D$-dimensional gapped Dirac fermion vacuum, either on lattice continuum, have form with respect Hamiltonian. Strikingly, even conspire make subsystem system at zero temperature hot gapless system. propose concrete experiments cold atom simulators observe induced states.