Generation of continuous-variable high-dimensional entanglement with three degrees of freedom and multiplexing quantum dense coding:publisher's note

This publisher's note corrects the authorship in Photon.Res.10,2828(2022).

Generation of a continuous-variable quadripartite cluster state multiplexed in the spatial domain

As a highly entangled quantum network, the duster state has the potential for greater information capacity and use in measurement-based quantum computation. Here, we report generating a continuous-variable quadripartite ＂square＂ cluster state of multiplexing orthogonal spatial modes in a single optical parametric amplifier （OPA）, and further improve the quality of entanglement by optimizing the pump profile. We produce multimode en- tanglement of two first-order Hermite-Gauss modes within one beam in a single multimode OPA and transform it into a duster state by phase correction. Furthermore, the pump-profile dependence of the entanglement of this state is explored. Compared with fundamental mode pumping, an enhancement of approximately 33% is achieved using the suitable pump-profile mode. Our approach is potentially scalable to multimode entanglement in the spatial domain. Such spatial duster states may contribute to future schemes in spatial quantum information processing.

Generation of continuous-variable high-dimensional entanglement with three degrees of freedom and multiplexing quantum dense coding

High-dimensional entanglement is a critical foundation for the growing demand for information capacity to implement the high-capacity quantum task.Here,we report continuous-variable high-dimensional entanglement with three degrees of freedom(frequency,polarization,and orbital angular momentum)directly generated with a single type-II optical parametric oscillator(OPO)cavity.By compensating both for dispersion in frequency modes and astigmatism in higher-order transverse modes,the OPO is capable of oscillating simultaneously and outputting thousands of entanglement pairs.The three degrees of freedom high-dimensional entanglement are verified simultaneously possessing frequency comb,spin,and orbital angular momentum entanglement via 14pairs of Hermite–Gaussian mode correlations measurement.Then,the“space-frequency”multiplexing quantum dense coding communication is also demonstrated by using the entanglement resource.It shows the great superiority of high-dimensional entanglement in implementing the high-capacity quantum task.Apart from an increased channel capacity,it is possible to conduct deterministic high-dimensional quantum protocols,quantum imaging,and especially quantum computing.

Generation of temporal multimode squeezed states of femtosecond pulse light

Nonclassical optical frequency combs play essential roles in quantum computation in the continuous variable regime. In this work, we generate multimode nonclassical frequency comb states using a degenerate type-I synchronously pumped optical parametric oscillator and directly observe the squeezing of the leading five temporal modes of femtosecond pulsed light. The overlapping spectra of these modes mean that the temporal modes are suitable for use in real-world quantum information applications.