Today’s best quantum computers have fewer than 100 quantum bits (qubits), but future applications of quantum computing may require millions or more. Finding space for that many qubits will be tricky regardless of whether the qubits are made from trapped ions, superconductors, quantum dots or some other technology. Furthermore, as the number of qubits grows, so will the amount of wiring needed to control and connect them. All these wires generate heat, making quantum computers more prone to error.
To address these challenges, Ensar Vahapoglu and colleagues at the University of New South Wales (UNSW), Australia, developed a prototype device that replaces wires with a dielectric resonator located directly above a chip containing silicon quantum dots. These nanometre-sized particles have an outer shell and inner core made of semiconducting material, and they possess properties such as the intrinsic spin of the electron and its associated magnetic moment that enable them to act as qubits.
The UNSW team’s design frees up valuable space while delivering a uniform magnetic field across the chip, making it possible to control the spin of electrons in all the quantum dots simultaneously in a way that requires less power and thus generates less heat.
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