title: Quantum electronics. Probing Johnson noise and ballistic transport in normal metals with a single-spin qubit.
abstract: Thermally induced electrical currents, known as Johnson noise, cause fluctuating electric and magnetic fields in proximity to a conductor. These fluctuations are intrinsically related to the conductivity of the metal. We use single-spin qubits associated with nitrogen-vacancy centers in diamond to probe Johnson noise in the vicinity of conductive silver films. Measurements of polycrystalline silver films over a range of distances (20 to 200 nanometers) and temperatures (10 to 300 kelvin) are consistent with the classically expected behavior of the magnetic fluctuations. However, we find that Johnson noise is markedly suppressed next to single-crystal films, indicative of a substantial deviation from Ohm's law at length scales below the electron mean free path. Our results are consistent with a generalized model that accounts for the ballistic motion of electrons in the metal, indicating that under the appropriate conditions, nearby electrodes may be used for controlling nanoscale optoelectronic, atomic, and solid-state quantum systems.
authors: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors: S
authors: S
authors: Kolkowitz
authors: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors: A
authors: A
authors: Safira
authors: Department of Physics, Harvard University, Cambridge, MA 02138, USA. Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
authors: A A
authors: AA
authors: High
authors: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
authors: R C
authors: RC
authors: Devlin
authors: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors: S
authors: S
authors: Choi
authors: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors: Q P
authors: QP
authors: Unterreithmeier
authors: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors: D
authors: D
authors: Patterson
authors: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors: A S
authors: AS
authors: Zibrov
authors: Department of Physics, University of Maryland, College Park, MD 20742, USA.
authors: V E
authors: VE
authors: Manucharyan
authors: Department of Physics, Harvard University, Cambridge, MA 02138, USA. Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA. lukin@physics.harvard.edu hongkun_park@harvard.edu.
authors: H
authors: H
authors: Park
authors: Department of Physics, Harvard University, Cambridge, MA 02138, USA. lukin@physics.harvard.edu hongkun_park@harvard.edu.
authors: M D
authors: MD
authors: Lukin