Utilizing 2D supplies, researchers have constructed superconducting qubits which are a fraction of earlier sizes, paving the way in which for smaller quantum computer systems. — ScienceDaily


For quantum computer systems to surpass their classical counterparts in pace and capability, their qubits — that are superconducting circuits that may exist in an infinite mixture of binary states — must be on the identical wavelength. Attaining this, nonetheless, has come at the price of measurement. Whereas the transistors utilized in classical computer systems have been shrunk right down to nanometer scales, superconducting qubits lately are nonetheless measured in millimeters — one millimeter is one million nanometers.

Mix qubits collectively into bigger and bigger circuit chips, and you find yourself with, comparatively talking, a giant bodily footprint, which suggests quantum computer systems take up a number of bodily house. These aren’t but gadgets we will carry in our backpacks or put on on our wrists.

To shrink qubits down whereas sustaining their efficiency, the sphere wants a brand new option to construct the capacitors that retailer the power that “powers” the qubits. In collaboration with Raytheon BBN Applied sciences, Wang Fong-Jen Professor James Hone’s lab at Columbia Engineering lately demonstrated a superconducting qubit capacitor constructed with 2D supplies that is a fraction of earlier sizes.

To construct qubit chips beforehand, engineers have had to make use of planar capacitors, which set the mandatory charged plates aspect by aspect. Stacking these plates would save house, however the metals utilized in standard parallel capacitors intrude with qubit info storage. Within the present work, printed on November 18 in Nano Letters, Hone’s PhD college students Abhinandan Antony and Anjaly Rajendra sandwiched an insulating layer of boron nitride between two charged plates of superconducting niobium dieselenide. These layers are every only a single atom thick and held collectively by van der Waals forces, the weak interplay between electrons. The workforce then mixed their capacitors with aluminum circuits to create a chip containing two qubits with an space of 109 sq. micrometers and simply 35 nanometers thick — that is 1,000 occasions smaller than chips produced below standard approaches.

After they cooled their qubit chip down to only above absolute zero, the qubits discovered the identical wavelength. The workforce additionally noticed key traits that confirmed that the 2 qubits had been changing into entangled and appearing as a single unit, a phenomenon often called quantum coherence; that might imply the qubit’s quantum state might be manipulated and browse out through electrical pulses, mentioned Hone. The coherence time was brief — a bit of over 1 microsecond, in comparison with about 10 microseconds for a conventionally constructed coplanar capacitor, however that is solely a primary step in exploring the usage of 2D supplies on this space, he mentioned.

Separate work printed on arXiv in August from researchers at MIT additionally took benefit of niobium diselenide and boron nitride to construct parallel-plate capacitors for qubits. The gadgets studied by the MIT workforce confirmed even longer coherence occasions — as much as 25 microseconds — indicating that there’s nonetheless room to additional enhance efficiency.

From right here, Hone and his workforce will proceed refining their fabrication strategies and take a look at different kinds of 2D supplies to extend coherence occasions, which mirror how lengthy the qubit is storing info. New machine designs ought to be capable of shrink issues down even additional, mentioned Hone, by combining the weather right into a single van der Waals stack or by deploying 2D supplies for different components of the circuit.

“We now know that 2D supplies might maintain the important thing to creating quantum computer systems potential,” Hone mentioned. “It’s nonetheless very early days, however findings like these will spur researchers worldwide to think about novel purposes of 2D supplies. We hope to see much more work on this route going ahead.”

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Supplies supplied by Columbia College Faculty of Engineering and Utilized Science. Unique written by Ellen Neff. Notice: Content material could also be edited for type and size.

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