Circuit Simulates One-Dimensional Quantum System

According to the laws of classical physics, atoms should stand perfectly still at absolute zero. However, this classical prediction violates the Heisenberg uncertainty principle, which says particles always fluctuate, even at zero temperature. Such fluctuations can drive a transition between two quantum phases at zero temperature, much like thermal fluctuations drive a phase transition at finite temperatures. While quantum phase transitions have been observed in a handful of condensed-matter systems, it remains challenging to test them in experiments. Frédéric Pierre at the University of Paris Sud and collaborators have now demonstrated an electronic circuit that can simulate a quantum phase transition that is expected to occur in a one-dimensional (1D) quantum liquid, such as electrons in a long, thin wire [1]. In such a liquid, the presence of an impurity can trigger the transition of the otherwise conducting wire to an insulating state. By simulating this insulator-to-metal transition, with unprecedented control over the parameters governing the transition, the team was able to test previously inaccessible aspects of a fundamental theory for 1D quantum systems. The approach may pave the way to simulating other quantum phase transitions using electronic devices.