Quantum state preparation using cavities and quantum memories

Abstract

Quantum state engineering has seen important developments over the last decade. The use of hybrid protocols, combining the discrete and continuous variables of light, can achieve high detection efficiencies, making them a good candidate for the production of non-classical states. Schrodinger cat states (SCSs), superpositions of two coherent states |α〉 in phase opposition (ψ cat ) 〉 |α〉 ± |-α〉), constitute an important member of this family. Such states have found promising applications in testing fundamental concepts, in quantum cryptography, and in quantum information, making them highly popular in the quantum optics domain [1, 2]. The SCSs produced so far in free space had small amplitudes α, limiting their applicability. One can increase α with iterative protocols [3, 4] but the probabilistic nature of such methods makes the success probability drops as α grows. As it can drastically increase the success rate of such iterative protocols, the use of quantum memories appears to be a cornerstone for the generation of quantum states. To produce states of large amplitudes at a high repetition rate, we start by preparing a first building block, namely a single-photon generator, and we then look for the implementation of a cavity to store the produced quantum state.