Quantum Theory Seminar: Lev-Arcady Sellem, Universite de Sherbrooke

Taming the environment of Gottesman-Kitaev-Preskill qubits

At first sight, dissipative processes are the source of quantum decoherence and limit the timescale over which a given system can be controlled. On the other hand, from a control theoretic point of view, the availability of dissipative processes also opens new avenues, not the least of which being the stabilization of quantum systems. In practice, one usually cannot choose the dissipative processes at work nor their steady states. However, assuming sufficiently rich interactions can be engineered, existing processes can sometimes be hijacked to emulate inaccessible nonphysical dissipative processes - the environment then goes from spectator to ally. This strategy, known as quantum reservoir engineering, can be traced back to the seminal work of Alfred Kastler on optical pumping.  

In this talk, we will present applications of quantum reservoir engineering for quantum information processing, and in particular for the stabilization of Gottesman–Kitaev–Preskill codes, a promising family of bosonic quantum error correction codes that recently surpassed break-even logical performance. We will present the current state of the art method for the stabilization of GKP codes as well as recently proposed avenues for improvement of their logical lifetime.