Searching for robust quantum memories in many coupled oscillators

The relation between microscopic symmetries in the system-environment interaction and the emergence of robust states is studied for many linearly coupled harmonic oscillators. Different types of symmetry, which are introduced into the model as terms in the coupling constants between each systemʼs oscillator and a common reservoir, lead to distinct robust modes. Since these modes are partially or completely immune to the symmetric part of the environmental noise, they are good candidates for building quantum memories. A comparison of the model investigated here, with bilinear system-reservoir coupling, and a model where such coupling presents an exponential dependence on the variables of interest is performed.

► Macroscopic symmetries may lead to microscopic ones in system-environment coupling.
► Robust modes related to these symmetries are found for N coupled oscillators.
► They can be used to enhance the lifetime of quantum memories.
► They can be built in cavity modes in photonic-band-gap material or trapped ions.