• 'Hot' spin quantum bits in silicon trans

    From ScienceDaily@1:317/3 to All on Fri Mar 25 22:30:40 2022
    'Hot' spin quantum bits in silicon transistors

    Date:
    March 25, 2022
    Source:
    https://www.unibas.ch/en.html
    Summary:
    Quantum bits (qubits) are the smallest units of information in
    a quantum computer. Currently, one of the biggest challenges
    in developing this kind of powerful computer is scalability. A
    research group has now made a breakthrough in this area.



    FULL STORY ========================================================================== Quantum bits (qubits) are the smallest units of information in a quantum computer. Currently, one of the biggest challenges in developing this kind
    of powerful computer is scalability. A research group at the University
    of Basel, working with the IBM Research Laboratory in Ru"schlikon,
    has made a breakthrough in this area.


    ========================================================================== Quantum computers promise unprecedented computing power, but to
    date prototypes have been based on just a handful of computing
    units. Exploiting the potential of this new generation of computers
    requires combining large quantities of qubits.

    It is a scalability problem which once affected classic computers, as
    well; in that case it was solved with transistors integrated into silicon chips. The research team led by Dr. Andreas Kuhlmann and Professor Dominik Zumbu"hl from the University of Basel has now come up with silicon-based
    qubits that are very similar in design to classic silicon transistors. The researchers published their findings in the journal Nature Electronics.

    Building on classic silicon technology In classic computers, the solution
    to the scalability problem lay in silicon chips, which today include
    billions of "fin field-effect transistors" (FinFETs). These FinFETs are
    small enough for quantum applications; at very low temperatures near
    absolute zero (0 kelvin or -273.15 degrees Celsius), a single electron
    with a negative charge or a "hole" with a positive charge can act as
    a spin qubit. Spin qubits store quantum information in the two states
    spin-up (intrinsic angular momentum up) and spin-down (intrinsic angular momentum down).

    The qubits developed by Kuhlmann's team are based on FinFET architecture
    and use holes as spin qubits. In contrast with electron spin, hole
    spin in silicon nanostructures can be directly manipulated with fast
    electrical signals.

    Potential for higher operating temperatures Another major obstacle to scalability is temperature; previous qubit systems typically had to
    operate at an extremely low range of about 0.1 kelvin.

    Controlling each qubit requires additional measuring lines to connect the control electronics at room temperature to the qubits in the cryostat --
    a cooling unit which generates extremely low temperatures. The number of
    these measuring lines is limited because each line produces heat. This inevitably creates a bottleneck in the wiring, which in turn sets a
    limit to scaling.

    Circumventing this "wiring bottleneck" is one of the main goals
    of Kuhlmann's research group, and requires measurement and control
    electronics to be built directly into the cooling unit. "However,
    integrating these electronics requires qubit operation at temperatures
    above 1 kelvin, with the cooling power of the cryostats increasing sharply
    to compensate for the heat dissipation of the control electronics,"
    explains Dr. Leon Camenzind of the Department of Physics at the University
    of Basel. Doctoral student Simon Geyer, who shares lead authorship of
    the study with Camenzind, adds, "We have overcome the 4 kelvin-mark
    with our qubits, reaching the boiling point of liquid helium. Here we
    can achieve much greater cooling power, which allows for integration
    of state-of-the-art cryogenic control technology." Close to industry
    standards Working with proven technology such as FinFET architecture
    to build a quantum computer offers the potential for scaling up to very
    large numbers of qubits.

    "Our approach of building on existing silicon technology puts us close
    to industry practice," says Kuhlmann. The samples were created at the
    Binnig and Rohrer Nanotechnology Center at the IBM Research Zurich
    laboratory in Ru"schlikon, a partner of the NCCR SPIN, which is based
    at the University of Basel and counts the research team as a member.


    ========================================================================== Story Source: Materials provided by https://www.unibas.ch/en.html. Note: Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Leon C. Camenzind, Simon Geyer, Andreas Fuhrer, Richard
    J. Warburton,
    Dominik M. Zumbu"hl, Andreas V. Kuhlmann. A hole spin qubit in a fin
    field-effect transistor above 4 kelvin. Nature Electronics,
    2022; DOI: 10.1038/s41928-022-00722-0 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220325093819.htm

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