• Tiny magnets could hold the secret to ne

    From ScienceDaily@1:317/3 to All on Mon Mar 21 22:30:46 2022
    Tiny magnets could hold the secret to new quantum computers

    Date:
    March 21, 2022
    Source:
    DOE/Argonne National Laboratory
    Summary:
    Scientists have discovered a type of magnetic behavior that could
    help enable magnetically based quantum devices.



    FULL STORY ========================================================================== Magnetic interactions could point to miniaturizable quantum devices.


    ==========================================================================
    From MRI machines to computer hard disk storage, magnetism has played a
    role in pivotal discoveries that reshape our society. In the new field
    of quantum computing, magnetic interactions could play a role in relaying quantum information.

    In new research from the U.S. Department of Energy's (DOE) Argonne
    National Laboratory, scientists have achieved efficient quantum coupling between two distant magnetic devices, which can host a certain type of
    magnetic excitations called magnons. These excitations happen when an
    electric current generates a magnetic field. Coupling allows magnons to exchange energy and information.

    This kind of coupling may be useful for creating new quantum information technology devices.

    "Remote coupling of magnons is the first step, or almost a prerequisite,
    for doing quantum work with magnetic systems," said Argonne senior
    scientist Valentine Novosad, an author of the study. ​"We show
    the ability for these magnons to communicate instantly with each other
    at a distance." This instant communication does not require sending a
    message between magnons limited by the speed of light. It is analogous
    to what physicists call quantum entanglement.

    Following on from a 2019 study, the researchers sought to create a
    system that would allow magnetic excitations to talk to one another at
    a distance in a superconducting circuit. This would allow the magnons
    to potentially form the basis of a type of quantum computer. For the
    basic underpinnings of a viable quantum computer, researchers need the particles to be coupled and stay coupled for a long time.

    In order to achieve a strong coupling effect, researchers have built
    a superconducting circuit and used two small yttrium iron garnet (YIG)
    magnetic spheres embedded on the circuit. This material, which supports magnonic excitations, ensures efficient and low-loss coupling for the
    magnetic spheres.

    The two spheres are both magnetically coupled to a shared superconducting resonator in the circuit, which acts like a telephone line to create
    strong coupling between the two spheres even when they are almost
    a centimeter away from each other -- 30 times the distance of their
    diameters.

    "This is a significant achievement," said Argonne materials scientist
    Yi Li, lead author of the study. ​"Similar effects can also be
    observed between magnons and superconducting resonators, but this time
    we did it between two magnon resonators without direct interaction. The coupling comes from indirect interaction between the two spheres and
    the shared superconducting resonator." One additional improvement
    over the 2019 study involved the longer coherence of the magnons in
    the magnetic resonator. ​"If you speak in a cave, you may hear an
    echo," said Novosad. ​"The longer that echo lasts, the longer the coherence." "Before, we definitely saw a relationship between magnons
    and a superconducting resonator, but in this study their coherence times
    are much longer because of the use of the spheres, which is why we can
    see evidence of separated magnons talking to each other," Li added.

    According to Li, because the magnetic spins are highly concentrated
    in the device, the study could point to miniaturizable quantum
    devices. ​"It's possible that tiny magnets could hold the secret
    to new quantum computers," he said.


    ========================================================================== Story Source: Materials provided by
    DOE/Argonne_National_Laboratory. Original written by Jared Sagoff. Note: Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Yi Li, Volodymyr G. Yefremenko, Marharyta Lisovenko, Cody
    Trevillian,
    Tomas Polakovic, Thomas W. Cecil, Peter S. Barry, John Pearson,
    Ralu Divan, Vasyl Tyberkevych, Clarence L. Chang, Ulrich Welp,
    Wai-Kwong Kwok, Valentine Novosad. Coherent Coupling of Two Remote
    Magnonic Resonators Mediated by Superconducting Circuits. Physical
    Review Letters, 2022; 128 (4) DOI: 10.1103/PhysRevLett.128.047701 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220321115840.htm

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