Absence and recovery of cost-precision tradeoff relations in quantum transport

The operation of many classical and quantum systems in nonequilibrium steady state is constrained by cost-precision (dissipation-fluctuation) tradeoff relations, delineated the thermodynamic uncertainty relation (TUR). However, coherent electronic nanojunctions can escape such a constraint, showing finite charge current nonzero entropic cost with vanishing fluctuations. Here, we analyze absence, restoration, relations fermionic under different affinities: voltage temperature biases. With analytic work simulations, show that both energy currents display absence if engineer transmission probability as boxcar function -- perfect hard cutoffs. Specifically for bias, standard TUR may be immediately violated depart from equilibrium, it exponentially suppressed increased voltage. beyond idealized, hard-cutoff energy-filtered functions, realistic models soft cutoffs or imperfect functions follow tradeoffs, eventually recover sufficiently far equilibrium. existence thus suggested generic feature transport junctions.