Abstract
We introduce the “displacemon” electromechanical architecture that comprises a vibrating nanobeam, e.g., a carbon nanotube, flux coupled to a superconducting qubit. This platform can achieve strong and even ultrastrong coupling, enabling a variety of quantum protocols. We use this system to describe a protocol for generating and measuring quantum interference between trajectories of a nanomechanical resonator. The scheme uses a sequence of qubit manipulations and measurements to cool the resonator, to apply two effective diffraction gratings, and then to measure the resulting interference pattern. We demonstrate the feasibility of generating a spatially distinct quantum superposition state of motion containing more than nucleons using a vibrating nanotube acting as a junction in this new superconducting qubit configuration.
- Received 30 October 2017
- Revised 28 March 2018
DOI:https://doi.org/10.1103/PhysRevX.8.021052
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Predicting the movement of small particles such as electrons requires the concept of quantum superposition, in which an object appears to traverse multiple paths simultaneously. When these paths recombine, they create an interference pattern that cannot be explained using one path alone. Such superpositions have been observed in photons and single trapped atoms. However, it is not clear why larger objects do not usually show this behavior. In this paper, we propose a device that can measure quantum interference in objects containing roughly one million atoms.
Currently, the largest objects that demonstrate quantum interference are molecules comprising hundreds of atoms fired through gratings. Our device, which we call a displacemon, consists of a vibrating carbon nanotube connected to a superconducting quantum bit (qubit). Using computer models and calculations, we show how a series of qubit manipulations creates an effective diffraction grating that reveals an interference pattern based on the movement of the nanotube.
Our technique could extend the mass range of objects exhibiting quantum interference by up to 3 orders of magnitude, paving the way for new tests of quantum collapse theories and the limits of quantum superposition.
