Hybrid discrete- and continuous-variable quantum information

Abstract

The development of quantum information processing has traditionally followed two separate and not immediately connected lines of study. The main line has focused on the implementation of quantum bit (qubit) based protocols whereas the other line has been devoted to implementations based on high-dimensional Gaussian states (such as coherent and squeezed states). The separation has been driven by the experimental difficulty in interconnecting the standard technologies of the two lines. However, in recent years, there has been a significant experimental progress in refining and connecting the technologies of the two fields which has resulted in the development and experimental realization of numerous new hybrid protocols. In this Review, we summarize these recent efforts on hybridizing the two types of schemes based on discrete and continuous variables.

Quantum Teleportation Between Discrete and Continuous Encodings of an Optical Qubit

“…Taking advantage of these protocols however requires a procedure for transferring quantum data between continuous and discrete qubit systems [4,9]; hybrid teleportation is therefore identified as one of the three key priorities for quantum teleportation science [10]. In this work we make a step towards this goal, demonstrating quantum teleportation by means of a hybrid entangled channel.…”

“…For example, using hybrid methods in quantum computing [5] and error correction [6] is favorable, compared to the mainstream CV and DV protocols, in terms of the number of resources required. Long-distance distribution of CV entanglement requires hybrid processing to mitigate the effect of propagation losses [7,8].Taking advantage of these protocols however requires a procedure for transferring quantum data between continuous and discrete qubit systems [4,9]; hybrid teleportation is therefore identified as one of the three key priorities for quantum teleportation science [10]. In this work we make a step towards this goal, demonstrating quantum teleportation by means of a hybrid entangled channel.…”

“…This flexibility allows hybrid quantum technologies to offer protocols which are superior to both pure CV and DV solutions [4]. For example, using hybrid methods in quantum computing [5] and error correction [6] is favorable, compared to the mainstream CV and DV protocols, in terms of the number of resources required.…”

“…Fortes of both can thereby be employed at once; for example, the continuous part takes advantage of the de- terministic state preparation and relatively simple integration with existing information technologies [2], while the discrete side benefits from a natural photodetection basis and "built-in" entanglement distillation after losses [3]. This flexibility allows hybrid quantum technologies to offer protocols which are superior to both pure CV and DV solutions [4]. For example, using hybrid methods in quantum computing [5] and error correction [6] is favorable, compared to the mainstream CV and DV protocols, in terms of the number of resources required.…”

Thermal state truncation by using quantum-scissors device

“…However, in the recent several decades, some probabilistic schemes are proposed to generate and manipulate non-Gaussian states [6][7][8]. Many schemes work in postselection [9], that is, the generated state is accepted conditionally on a measurement outcome.…”