Multimode entanglement in reconfigurable graph states using optical frequency combs

Abstract

Multimode entanglement is an essential resource for quantum information processing and quantum metrology. However, multimode entangled states are generally constructed by targeting a specific graph configuration. This yields to a fixed experimental setup that therefore exhibits reduced versatility and scalability. Here we demonstrate an optical on-demand, reconfigurable multimode entangled state, using an intrinsically multimode quantum resource and a homodyne detection apparatus. Without altering either the initial squeezing source or experimental architecture, we realize the construction of thirteen cluster states of various sizes and connectivities as well as the implementation of a secret sharing protocol. In particular, this system enables the interrogation of quantum correlations and fluctuations for any multimode Gaussian state. This initiates an avenue for implementing on-demand quantum information processing by only adapting the measurement process and not the experimental layout.

Remote Generation of Wigner Negativity through Einstein-Podolsky-Rosen Steering

“…The key idea of such a quantum network, be it for communication or for distributed computation, is to connect a large number of nodes via quantum entanglement [3,4]. A platform that is particularly promising for such applications is continuous-variable quantum optics, where large entangled graph states can be deterministically produced [5][6][7][8][9]. Even though this allows us to produce intricate quantum networks, the resulting Gaussian quantum states still have a positive Wigner function.Negativity of the Wigner function has been identified as a necessary ingredient for implementing processes that cannot be simulated efficiently with classical resources [10,11], and is therefore an essential resource [12,13] to achieve a quantum advantage.…”

“…Remark that the conditions (7) and (11) are independent on the displacement of the state. Thus, in principle the displacement plays no role in whether or not W − f (β f ) reaches negative values.…”

“…We can also subtract a photon from one of the modes in a larger multimode state. In particular, we consider CV graph states [5][6][7][8][9], which form the backbone of measurement-based quantum computing in CV [41], and have tractable entanglement properties. Recently, EPR steering was experimentally observed in such a system [31].…”

Deterministic multi-mode nonlinear coupling for quantum circuits

“…This issue can be resolved by considering Gaussian processing (14) as part of the nonlinear state preparation (13). Interestingly, the numerical analysis reveals that the second linear coupling is not even necessary and parameter of the second beam splitter can be se to θ 2 =0.…”

Reconfigurable optical implementation of quantum complex networks

“…The quantum nature of the networks is provided by the ability to initialize the oscillators in quantum states and/or generate entanglement connections between nodes. Part of this strategy has already demonstrated the fabrication of multipartite entangled states [39] and cluster states [35,40]. Here we address a more general scenario, with additional tools and a specific mapping, for the implementation of quantum complex networks.…”