title: Capabilities of a perturbed toric code as a quantum memory.
abstract: We analyze the effect of typical, unknown perturbations on the 2D toric code when acting as a quantum memory, incorporating the effects of error correction on readout. By transforming the system into a 1D transverse Ising model undergoing an instantaneous quench, and making extensive use of Lieb-Robinson bounds, we prove that for a large class of perturbations, the survival time of stored information grows at least logarithmically with the system size. A uniform magnetic field saturates this scaling behavior. We show that randomizing the stabilizer strengths gives a polynomial survival time with a degree that depends on the strength of the perturbation.
authors.affiliation: Centre for Quantum Technologies, National University of Singapore, Singapore.
authors.forename: Alastair
authors.initials: A
authors.lastname: Kay