Using a biased qubit to probe complex systems

摘要: Complex mesoscopic systems play increasingly important roles in modern science, from understanding biological functions at the molecular level to designing solid-state information processing devices. The operation of these typically depends on their energetic structure, yet probing energy landscape can be extremely challenging; they have many degrees freedom, which may hard isolate and measure independently. Here, we show that a qubit (a two-level quantum system) with biased splitting directly probe spectral properties complex system, without knowledge how couple. Our work is based completely positive trace-preserving map formalism, treats any unknown dynamics as ``black-box'' process. This black box contains about system interacts, access by measuring survival probability initial state function process time. Fourier transforming results yields spectrum system. Without making assumptions strength or form its coupling, our could determine aspects molecule's well as, cases, test for coherent superposition eigenstates.