Time-Reversal Symmetry and Universal Conductance Fluctuations in a Driven Two-Level System
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Gustavsson-2013-Time-Reversal Symmetry and Universal Conductance Fluctuations.pdf
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Author(s)
Gustavsson, Simon
Bylander, Jonas
Oliver, William D.
Date Issued
January 2013
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Gustavsson, Simon, Jonas Bylander, and William D. Oliver. “Time-Reversal Symmetry and Universal Conductance Fluctuations in a Driven Two-Level System.” Physical Review Letters 110.1 (2013). © 2013 American Physical Society
Version
Final published version
Abstract
In the presence of time-reversal symmetry, quantum interference gives strong corrections to the electric conductivity of disordered systems. The self-interference of an electron wave function traveling time-reversed paths leads to effects such as weak localization and universal conductance fluctuations. Here, we investigate the effects of broken time-reversal symmetry in a driven artificial two-level system. Using a superconducting flux qubit, we implement scattering events as multiple Landau-Zener transitions by driving the qubit periodically back and forth through an avoided crossing. Interference between different qubit trajectories gives rise to a speckle pattern in the qubit transition rate, similar to the interference patterns created when coherent light is scattered off a disordered potential. Since the scattering events are imposed by the driving protocol, we can control the time-reversal symmetry of the system by making the drive waveform symmetric or asymmetric in time. We find that the fluctuations of the transition rate exhibit a sharp peak when the drive is time symmetric, similar to universal conductance fluctuations in electronic transport through mesoscopic systems.
MIT Department
Lincoln Laboratory
Massachusetts Institute of Technology. Research Laboratory of Electronics
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.110.016603
