A significant hurdle in the road towards practical quantum computers involves the difficulty of supercooling qubits within the systems. Typically, these qubits have to be cooled down to temperatures below 100 mK (near absolute zero). But in a paper published recently on Nature, Intel in collaboration with QuTech has taken a slightly different approach towards the issue of supercooling.
In the paper titled "Universal quantum logic in hot silicon qubits", researchers have successfully demonstrated the control of 'hot' qubits. These hot qubits, as the name implies, are more tolerant towards higher temperatures (above 1 K) in comparison to traditional qubits, which require temperature levels tantalizingly close to absolute zero.
Here we show that silicon quantum dots can have sufficient thermal robustness to enable the execution of a universal gate set at temperatures greater than one kelvin.
Specifically, the research shows a full two-qubit logic in a quantum circuit operating at 1.1 K. The team took inspiration from recent studies into electron spins that have hinted at a platform that can be operated at higher temperatures by demonstrating long spin lifetimes, gate-based spin readout, and coherent single-spin control. Building on these, the team at Intel and QuTech was able to control these qubits and carry out specific measurements on them as well.
In addition, we show individual coherent control of two qubits and measure single-qubit fidelities of up to 99.3 per cent. We demonstrate the tunability of the exchange interaction between the two spins from 0.5 to 18 megahertz and use it to execute coherent two-qubit controlled rotations.
However, the demonstration was based on a two-qubit system, which is substantially smaller than most commercial quantum computers on the cloud today. But the researchers stated that their work builds towards quantum integrated circuits that house control circuitry, as well as quantum hardware on a single chip, thereby providing a scalable approach towards practical quantum computers. More information can be found here.