Heralded generation of asymmetric polarized entangled qutrits

Abstract

In quantum information processing, quantum entanglement plays a very important role with special physical property, which makes the quantum information have many new characteristics that the classical information do not have, and provides a new physical resource in the transmission and processing of information. Compared with classical bit, quantum entanglement, especially the high dimensional quantum entanglement (i.e., entangled qudit), has a large information storage space and good security confidentiality, which means stronger nonlocality and much more powerful capability in quantum information processing. In this sense, here we focus on the topic of polarized entangled qudit generation, especially the asymmetric entangled qutrit generation, which hasnt been discussed before. The initial states could be an entangled photon pair and two single photons. Using two qubus beams as ancilla, and based on the cross phase modulation, the initial quantum states could be projected into different subspaces, which include the desired one. Finally, through the bi-photon Hong-Ou-Mandel interference, the asymmetric entangled qutrit could be generated. This scheme is heralded by the detection results of three ideal photon number non-resolving detectors (PNNDs). If neither of the three ideal PNNDs registers photons, the generation is successful; otherwise, any click appearing on one of the three ideal PNNDs means the failure of the generation. The corresponding success probability of maximally entangled qutrit generation is 3/64, which is relatively small. However, the success probability could be increased to 3/8 by using the special photon detectors, associated with the quantum non- demolition detectors (QNDs) replacing the ideal PNNDs. The more efficient scheme is still heralded, so the generated entangled qutrit could be used flexibly in the quantum information processing.