Essential quantum computer component miniaturized by two orders of magnitude

Qubits, or quantum bits, are the key building blocks at the heart of every quantum computer. In order to perform a computation, signals are directed to and from qubits. However, qubits are extremely sensitive to interference from their environment, and need to be shielded from outside signals, in particular from magnetic fields. It is a serious problem that the devices built to shield qubits from unwanted signals, known as nonreciprocal devices, produce magnetic fields themselves. Moreover, they are several centimeters in size, which is problematic, given that a large number of such elements is required in each quantum processor.

Now, scientists at the Institute of Science and Technology Austria (IST Austria), simultaneously with competing groups in Switzerland and the United States, have decreased the size of nonreciprocal devices by two orders of magnitude. Their device, which they compare to a traffic roundabout for photons, is only about a tenth of a millimeter in size, and—more importantly—it is not magnetic. Their study was published in the open access journal Nature Communications.