Deterministic quantum entanglement among multiple quantum nodes

Abstract

Quantum entanglement is a significant quantum resource, which plays a central role in quantum communication. For realizing quantum information network, it is important to establish deterministic quantum entanglement among multiple spatial-separated quantum memories, and then the stored entanglement is transferred into the quantum channels for distributing and transmitting the quantum information at the user-control time. Firstly, we introduce the scheme of deterministic generation polarization squeezed state at 795 nm. A pair of quadrature amplitude squeezed optical fields are prepared by two degenerate optical parameter amplifiers pumped by a laser at 398 nm, and then the polarization squeezed state of light appears by combining the generated two quadrature amplitude squeezed optical beams on a polarizing beam splitter. Secondly, we present the experimental demonstration of tripartite polarization entanglement described by Stokes operators of optical field. The quadrature tripartite entangled states of light corresponding to the resonance with D1 line of rubidium atoms are transformed into the continuous-variable polarization entanglement via polarization beam splitter with three bright local optical beams. Finally, we propose the generation, storage and transfer of deterministic quantum entanglement among three spatially separated atomic ensembles. By the method of electromagnetically induced transparency light-matter interaction, the optical multiple entangled state is mapped into three distant atomic ensembles to build the entanglement among three atomic spin waves. Then, the quantum noise of entanglement stored in the atomic ensembles is transferred to the three space-seperated quadrature entangled light fields through three quantum channels. The existence of entanglement among the three released beams verifies that the system has the ability to maintain the multipartite entanglement. This protocol realizes the entanglement among three distant quantum nodes, and it can be extended to quantum network with more quantum nodes. All of these lay the foundation for realizing the large-scale quantum network communication in the future.

Broadband multi-channel quantum noise suppression and phase-sensitive modulation based on entangled beam

“…The phenomenon of multiple EIT-like quantum interference entanglement channels appearing simultaneously is beneficial to improve the efficiency of quantum information transfer. It has potential applications in the fields of quantum communication [41][42][43] and quantum storage, [44] etc.…”

Dissipative preparation of multipartite Greenberger-Horne-Zeilinger states of Rydberg atoms*

“…Quantum entanglement is one of the most remarkable features in quantum physics, as well as a valuable resource in the fields of quantum communication, [1][2][3][4][5][6] quantum computing, [7][8][9][10][11][12] and other quantum information processing. [13][14][15][16][17][18][19][20][21][22] With the development of quantum information science, bipartite entanglement has been intensively explored, and several milestones have been achieved. [23][24][25] In recent years, researchers have become increasingly interested in the study of multipartite entanglements.…”

Generation of tripartite Einstein–Podolsky–Rosen steering by cascaded nonlinear process*

“…In response to EPR paradox, Schrödinger proposed the concept of quantum steering (EPR steering) [2][3][4] which described by using different observables to detect one of the particles, causing the corresponding one to collapse to a different state. In the decades after this concept was proposed, scientists have been focusing on quantum entanglement [5][6][7][8] and Bell nonlocality. [9,10] Until 2007, Wiseman et al [11,12] found that in the form of quantum information tasks, quantum steering can predict a new property that cannot be described by the local hidden state.…”