Dissipative Encoding of Quantum Information

Abstract

We formalize the problem of dissipative quantum encoding, and explore the advantages of using Markovian evolution to prepare a quantum code in the desired logical space, with emphasis on discrete-time dynamics and the possibility of exact finite-time convergence. In particular, we investigate robustness of the encoding dynamics and their ability to tolerate initialization errors, thanks to the existence of non-trivial basins of attraction. As a key application, we show that for stabilizer quantum codes on qubits, a finite-time dissipative encoder may always be constructed, by using at most a number of quantum maps determined by the number of stabilizer generators. We find that even in situations where the target code lacks gauge degrees of freedom in its subsystem form, dissipative encoders afford nontrivial robustness against initialization errors, thus overcoming a limitation of purely unitary encoding procedures. Our general results are illustrated in a number of relevant examples, including Kitaev's toric code.

Generation of a maximally entangled state using collective optical pumping

“…The protocol can be practically beneficial in experiments limited by global errors, especially as a method of purifying lower-fidelity Bell states. Dissipative generation of high-fidelity entangled states could find application in a variety of quantum information processing tasks, such as dissipative encoding [50], error-corrected quantum sensing [51], and as a supply of entangled resource states for quantum gate teleportation [52].…”