PRL NTU team realizes preparation and modulation of multi-photon entangled states on optical quantum chips
Multiparticle entangled states not only play an important role in testing the fundamental principles of quantum physics, but also are an important resource for realizing large-scale quantum information processing. Among many kinds of multi-particle entangled states, the Dicke state proposed by R.H. Dicke in 1954 is of great importance for studying the nature of multi-particle quantum entanglement and constructing multi-user quantum networks. Recently, the team of Xiaosong Ma, Yanqing Lu and Shining Zhu at Nanjing University has realized for the first time the preparation of multiple four-photon Dicke states on a silicon-based optical quantum chip, and achieved high-precision global coherent regulation of multi-photon entangled states using an on-chip quantum control unit. This work enriches the variety of multi-photon entangled states prepared on-chip and is expected to have important applications in quantum networks and quantum precision measurements.
The concept of multi-photon entanglement creation and control.
Quantum entanglement is a quantum phenomenon beyond the scope of classical physics, and is an important resource for studying quantum fundamental physics and realizing quantum information processing technology. Integrated optics and photonic chips provide an ideal platform for the preparation, manipulation and measurement of optical quantum entangled states. Thanks to the complementary metal oxide semiconductor process (CMOS) compatibility, strong nonlinearity, high integration, and easy scalability, integrated optical quantum chips show unique advantages in realizing future large-scale optical quantum computing and information processing.
The research team prepared a high-quality frequency-simplified four-photon Dicke state light source on a silicon-based chip based on integrated optics technology. The team used a two-Mach-Zender interferometer-type micro-ring resonator as a novel quantum light source on the chip to excite frequency-simple photon pairs with high yields and high signal-to-noise ratios through a two-color pulse pumping technique. The on-chip integrated optical link is used to distribute the generated photons, and the preparation of path-mode encoded multiphoton Dicke entangled states and their multiple coherent superposition states is realized. Based on this, the team achieved the first on-chip multi-photon entangled state lamination by high-precision on-chip quantum manipulation, and obtained a four-photon Dicke entangled state with 81.7% fidelity.
Further, the research team achieved global coherent regulation of arbitrary four-photon Dicke states by controlling the relative phase between on-chip sources. Based on this high-quality Dicke entangled state, the team experimentally demonstrates its potential application in multi-party quantum communication networks. This research provides an important basis for the on-chip preparation of reconfigurable, multi-body entangled quantum states and the application of quantum tuning techniques.
Diagram of the experimental setup. a. Optical microscope image of a four-photon Dicke state chip. b. Schematic diagram of the chip optical path. Two quantum light source modules on the chip are used to generate the entangled photon pairs; the linear quantum link module distributes these photons and then post-selects them to obtain the four-photon entanglement; the single quantum bit manipulation module regulates and measures the prepared entangled states. The control of the relative phase between the quantum light sources enables the global coherent regulation of the entire Dicke state. c. A two-color pulsed pumping system that excites the on-chip light sources to generate frequency-simple photon pairs.
The real part of the density matrix of different states.
Collective coherent control of the four-photon states.
On this occasion, Leizhen Chen, a Ph.D. student at the School of Physics, Nanjing University, was the first author of the article, and Liangliang Lu, a researcher, and Lijun Xia, a Ph.D. student, also made important contributions to the paper. Prof. Xiaosong Ma of School of Physics, Nanjing University, is the corresponding author of the article. Academician Zhu Shining and Professor Lu Yanqing of Nanjing University provided in-depth guidance to this work. This work was supported by the National Key Research and Development Program of China, the National Natural Science Foundation of China, the Frontier Technology Program of the Natural Science Foundation of Jiangsu Province, the Fundamental Research Funds of the Central Universities, and the Quantum Science and Technology Innovation Program.
This work was also supported by the School of Physics, the State Key Laboratory of Solid Microstructures, the Collaborative Innovation Center of Artificial Microstructure Science and Technology, and the Hefei National Laboratory of Nanjing University.
