An electronic quantum eraser

Creating and erasing quantum knowledge Particles in the quantum world can also assume wavelike properties. Researchers often use photons to illustrate this particle/wave duality, but electrons interact with each other, which might make them a better choice. Weisz et al. used electrons to create a “quantum eraser” (see the Perspective by Feldman). By taking advantage of the electrons' interaction, the researchers first acquired information about the electrons' path—a process that destroys their wavelike properties. Next, they deliberately erased this information in order to recover the electrons' wave nature. Science, this issue p. 1363; see also p. 1344 A device that illustrates the principle of complementarity in quantum mechanics has been implemented with electrons. [Also see Perspective by Feldman] The quantum eraser is a device that illustrates the quantum principle of complementarity and shows how a dephased system can regain its lost quantum behavior by erasing the “which-path” information already obtained about it. Thus far, quantum erasers were constructed predominantly in optical systems. Here, we present a realization of a quantum eraser in a mesoscopic electronic device. The use of interacting electrons, instead of noninteracting photons, allows control over the extracted information and a smooth variation of the degree of quantum erasure. The demonstrated system can serve as a first step toward a variety of more complex setups.