How Schrödinger’s Cats Help Us to Improve Quantum Computers

Thanks to technology inspired by Schrödinger’s Cat, quantum computers can have fewer overall components. A team of researchers at Amazon Web Services used “Bosonic Cat Qubits” to improve the ability of quantum computers to correct errors. Demonstration of quantum error correction, which requires reduced hardware overhead, is reported in a paper published in Nature.

This system uses so-called cat qubits (qubits are quantum equivalents to classic computing bits). It is designed to be resistant to certain types of noise and errors that can destroy the output of a quantum system. This approach requires fewer overall components to achieve quantum error correction than other designs.

Quantum computers are error prone to errors and limit the likelihood of exceeding the functionality of classic computers in a particular task. Quantum error correction is a useful way to reduce errors by expanding information to multiple qubits and allowing error identification and correction without breaking down calculations. However, most approaches to quantum error correction typically rely on a large number of additional kibits to provide adequate protection against errors, which can lead to an overall reduction in efficiency.

Researcher Harald Patterman and colleagues explore potentially efficient ways to implement quantum error correction using a type of qubit called boson cat qubit. These cat qubits are essentially highly resistant to one type of error (a bit called flip) at the expense of being likely to experience another type of thing (called a phase flip) at the expense of being more likely to experience another type of thing (called a phase flip). This error bias allows researchers to design quantum error correction codes that focus solely on handling phase flip errors, resulting in a much more efficient design that requires less additional kits.

The authors show superconducting quantum circuit devices using an array of CAT kibits, which has been shown to suppress errors from 1.75% to 1.65% per cycle for error correction codes with five cat kibits. Previously, dozens of additional kibits were required to achieve error suppression with larger error correction codes.

These results show that using boson cat qubits may be an efficient method for achieving quantum calculations of fault resistance. The authors suggest that systems have the potential to scale and can do so efficiently, but note that further optimization is required to improve performance to a level that could enable practical quantum computing applications.