Error correction is a key element of tomorrow’s massive scale quantum computer systems. Utilizing error correction, we are able to mix many “bodily qubits” (in our gadgets, these are small superconducting circuits that may retailer quantum info, however are delicate to noise) into an ensemble that works collectively to retailer a single “logical qubit” that’s extra sturdy to noise. Just some months in the past, we introduced that we had carried out a floor code quantum error correction experiment that exceeded the efficiency threshold required to get advantages from scaling up the system. Which means that, in precept, we are able to now make a near-perfect logical qubit by “merely” including increasingly bodily qubits.
Considering forward to the following steps on this journey raises the next questions:
- How can we decrease the variety of bodily qubits per logical qubit?
- How can we maximize the pace of logical operations and quantum algorithms?
One technique to make progress on each these questions, exemplified by the discharge of our Willow chip, is to enhance the standard of the bodily qubits (i.e., decrease bodily error charges). This reduces the required code distance (i.e. the minimal variety of simultaneous bodily errors required to supply a logical error) resulting in fewer bodily qubits per logical qubit and sooner logical operations, which usually scale with the code distance. Nevertheless, one other approach is to make the error correction code extra environment friendly.
Immediately, we’re excited to report the experimental demonstration of a “colour code” system that gives an advantageous different to the effectively studied floor code. In our newest Nature publication, “Scaling and logic within the colour code on a superconducting quantum processor”, we implement the constructing blocks required for a useful resource environment friendly, fault-tolerant quantum pc based mostly on the colour code. Similar to the floor code, the colour code is a technique to encode every logical qubit utilizing many bodily qubits in such a approach that errors will be detected and corrected as they happen. Nevertheless, the colour code makes use of a unique geometrical sample of parity measurement (i.e., a triangular patch of hexagonal tiles) which requires fewer bodily qubits and boasts extra environment friendly logical gates than the floor code, however this comes on the expense of requiring deeper bodily circuits and a unique decoding algorithm.