Nonequilibrium phase transition in transport through a driven quantum point contact

We study the transport of noninteracting fermions through a periodically driven quantum point contact (QPC) connecting two tight-binding chains. Initially, each chain is prepared in its own equilibrium state, generally with bias chemical potentials and temperatures. examine heating rate (or, alternatively, energy increase per cycle) nonequilibrium time-periodic steady state established after initial transient dynamics. find that vanishes identically when driving frequency exceeds bandwidth chain. first establish this fact for particular type QPCs where can be calculated analytically. Then we verify numerically phase transition present generic QPC. Finally, derive effect perturbatively leading order cases QPC Hamiltonian considered small perturbation. Strikingly, discover certain current averaged over cycle also above critical frequency, despite persistent bias. This shows act as frequency-controlled switch.