Add freedom for quantum circuitry simplicity

It might not quite “pave the way” for quantum computers, (every research announcement claims it will do just that) but a new approach to quantum circuitry reported by researchers at Bristol University might show a way around a significant obstacle.

Quantum circuits, the researchers explain, are extraordinarily complex things. One of the trickiest logic gate to implement in a quantum circuit is a controlled gate, one which only performs its operation if the “control bit” is in a particular state.

In traditional computing, each bit can be either 1 or 0. nice and simple. In quantum computing, each bit can be simultaneously 1, 0, and depending on the kind of qubit, many others as well. Translating this into a traditional controlled gate logic operation is prohibitively complex, preventing “the realization of even small-scale quantum circuits” according to the Bristol University press release.

So, in keeping with the quantum world’s general weirdness, the way to simplify things is to add an extra degree of freedom, to give the qubit another possible state to be in.

From the announcement: "By using an extra degree of freedom of quantum particles, we can realize the control operation in a novel way. We have constructed several controlled operations using this method," said Dr Xiao-Qi Zhou,. "This will significantly reduce the complexity of the circuits for quantum computing."

The work is published in Nature Communications here, and it is an open article, so you can read it even without subscription.