Quantum Computing with Schrödinger Cats
Quantum computers promise to accomplish tasks that are well beyond the reach of any classical computer. However, in order to gain computational advantage quantum-logic operations must be performed with ultrahigh degree of accuracy. Fortunately, with quantum error correction (QEC) it is possible to reliably carry out arbitrarily long quantum computation even with faulty hardware and software, provided the error rate is below some constant threshold. A popular choice of error-correcting code for many quantum computing architectures is the surface code. It exhibits small error detection circuits, nearest-neighbor operations and higher error threshold compared to other codes. However, the demanding hardware overhead and threshold requirements remain a hurdle for practical realization. In this talk I will present an elementary introduction to QEC with a focus on the surface code. I will then introduce a new type of qubit called the bosonic cat qubit which is realized in a driven non-linear oscillator. The cat-qubit realized in such a way has some in-built protection against errors in hardware and software. Finally, I will discuss how the requirements for the surface code tailored to cat-qubits can be greatly reduced.