Realizing a deterministic source of multipartite-entangled photonic qubits

Abstract

Sources of entangled electromagnetic radiation are a cornerstone in quantum information processing and offer unique opportunities for the study of quantum many-body physics in a controlled experimental setting. Generation of multi-mode entangled states of radiation with a large entanglement length, that is neither probabilistic nor restricted to generate specific types of states, remains challenging. Here, we demonstrate the fully deterministic generation of purely photonic entangled states such as the cluster, GHZ, and W state by sequentially emitting microwave photons from a controlled auxiliary system into a waveguide. We tomographically reconstruct the entire quantum many-body state for up to N = 4 photonic modes and infer the quantum state for even larger N from process tomography. We estimate that localizable entanglement persists over a distance of approximately ten photonic qubits.

Photonic resource state generation from a minimal number of quantum emitters

“…This daunting resource overhead can be avoided by instead using sequential generation schemes. References 22,23 put forward such an approach that works well for one-dimensional (1D) graph states 24 and has led to experimental demonstrations 25,26 . However, in the general case where the entanglement structure is more complicated, this method scales exponentially in the size of the target state and can lead to long generation circuits, motivating the search for more efficient approaches.…”

Proposal for generating complex microwave graph states using superconducting circuits

“…In 2020, Besse et al experimentally demonstrated how to use transmon qubits to generate entangled photonic qubits at microwave frequencies [1]. Specifically, they showed how to produce 1D photonic graph states.…”

“…In this work, we consider how to generate two types of microwave graph states: 2D lattice (cluster) states and all-photonic repeater states. Specifically, we address the following three questions: (1) What superconducting circuits can generate these states? (2) Which type of transmon qubit is better, fixed-frequency or tunable-frequency transmons?…”

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Microwave photonic graph states provide a promising approach for robust quantum communication between remote superconducting chips using microwave photons. Recently, Besse et al [1] demonstrated that 1D graph states can be generated using two transmon qubits. In this paper, we propose to use transmon qubits combined with other microwave devices to construct more complex graph states.

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Entanglement Dynamics Induced by a Squeezed Coherent Cavity Coupled Nonlinearly with a Qubit and Filled with a Kerr-Like Medium

“…The study of quantum coherence dynamics induced by open nonlinear qubit-photon systems has recently become a significant area that contributes to the development of potential quantum information applications [ 1 , 2 , 3 , 4 , 5 , 6 ]. We can cite as examples of potential applications in quantum teleportation protocol [ 7 ], cryptography [ 8 ], and computation [ 9 , 10 ], generation of entangled states [ 11 ]. Entanglement is an essential quantum information resource in quantum communication [ 12 ], it has been extensively explored theoretically and experimentally [ 13 , 14 ].…”