Quantum-to-classical transition is a fundamental open question in physics frontier. Quantum decoherence theory points out that the inevitable interaction with environment is a sink carrying away quantum coherence, which is responsible for the suppression of quantum superposition in open quantum system. Recently, quantum Darwinism theory further extends the role of environment, serving as communication channel, to explain the classical objectivity emerging in quantum measurement process. Here, we used a six-photon quantum simulator to investigate classical and quantum information proliferation in quantum Darwinism process. In the simulation, many environmental photons are scattered from an observed quantum system and they are collected and used to infer the system's state. We observed redundancy of system's classical information and suppression of quantum correlation in the fragments of environmental photons. Our results experimentally show that the classical objectivity of quantum system can be established through quantum Darwinism mechanism.

Ming Cheng Chen;Han Sen Zhong;Yuan Li;Dian Wu;Xi Lin Wang;Li Li;Nai Le Liu;Chao Yang Lu;建伟 潘

Science Bulletin

2019-5-15

We report a prolonged coherence time of the collective spin wave of a thermal R 87 b atomic ensemble in a paraffin-coated cell. The spin wave is prepared through a stimulated Raman process. The long coherence time is achieved by prolonging the lifetime of the spins with paraffin coating and minimize dephasing with optimal experimental configuration. The observation of the long-time-delayed-stimulated Stokes signal in the writing process suggests the prolonged lifetime of the prepared spins; a direct measurement of the decay of anti-Stokes signal in the reading process shows the coherence time is up to 300 μs after minimizing dephasing. This is 100 times longer than the reported coherence time in the similar experiments in thermal atomic ensembles based on the Duan-Lukin-Cirac-Zoller and its improved protocols. This prolonged coherence time sets the upper limit of the memory time in quantum repeaters based on such protocols, which is crucial for the realization of long-distance quantum communication. The previous reported fluorescence background in the writing process due to collision in a sample cell with buffer gas is also reduced in a cell without buffer gas.

Shuo Jiang;Xiao Ming Luo;Li Qing Chen;Bo Ning;Shuai Chen;Jing Yang Wang;Zhi Ping Zhong;建伟 潘

Physical Review A - Atomic, Molecular, and Optical Physics

2009-12-2

We demonstrate a photon-counting optical time-domain reflectometry with 42.19 dB dynamic range using an ultra-low noise up-conversion single photon detector. By employing the long-wave pump technique and a volume Bragg grating, we achieve a noise equivalent power of ?139.7 dBm/?Hz for our detector. We perform the OTDR experiments using a fiber of length approximate 217 km, and show that our system can identify defects along the entire fiber length in a measurement time of 13 minutes.

Guo Liang Shentu;Qi Chao Sun;Xiao Jiang;Xiao Dong Wang;Jason S. Pelc;M. M. Fejer;Qiang Zhang;建伟 潘

Optics Express

2013-10-21

Quantum interface of coherent optical field and atomic excitations plays an important role in quantum metrology and quantum information science. The electromagnetically-induced-Transparency (EIT) technique has shown versatile and powerful capability in many applications during the last decades. By using efficient EIT-based memory, we directly observed single-photon-level Ramsey interference and also high-contrast spectral transparency comb with a visibility up to about 0.81 at around the resonant line in cold atoms. The interference fringes are mainly influenced by the pulse repetition period, the waveform overlap of the slowed and retrieved signal pulses, and the coherent lifetime of the EIT memory. All these factors have been investigated in detail. Such high-contrast interference fringe may offer us methods for precision measurement and potential applications in areas of atomic clock and magnetometry.

Sheng Jun Yang;Jun Rui;Han Ning Dai;Xian Min Jin;Shuai Chen;建伟 潘

Physical Review A

2018-9-4

Ultracold atoms in optical lattices hold promise for the creation of entangled states for quantum technologies. Here we report on the generation, manipulation and detection of atomic spin entanglement in an optical superlattice. Using a spin-dependent superlattice, atomic spins in the left or right sites can be individually addressed and coherently manipulated with near-unity fidelities by microwave pulses. The spin entanglement of the two atoms in the double wells of the superlattice is generated via the dynamical evolution governed by spin superexchange. By monitoring the collisional atom loss with in situ absorption imaging we measure the spin correlations of the atoms inside the double wells and obtain a lower bound on the entanglement fidelity of 0.79 ± 0.06, and a violation of a Bell's inequality S = 2.21 ± 0.08.

Han Ning Dai;Bing Yang;Andreas Reingruber;Xiao Fan Xu;Xiao Jiang;宇翱 陈;Zhen Sheng Yuan;建伟 潘

Nature Physics

2016-8-2

We demonstrate the decoy-state quantum key distribution (QKD) with one-way quantum communication in polarization space over 102 km. Further, we simplify the experimental setup and use only one detector to implement the one-way decoy-state QKD over 75 km, with the advantage to overcome the security loopholes due to the efficiency mismatch of detectors. Our experimental implementation can really offer the unconditionally secure final keys. We use 3 different intensities of 0, 0.2, and 0.6 for the light sources in our experiment. In order to eliminate the influences of polarization mode dispersion in the long-distance single-mode optical fiber, an automatic polarization compensation system is utilized to implement the active compensation.

承志 彭;Jun Zhang;Dong Yang;Wei Bo Gao;Huai Xin Ma;浩 殷;和平 曾;Tao Yang;Xiang Bin Wang;建伟 潘

Physical Review Letters

2007

By pulsed s-shell resonant excitation of a single quantum dot-micropillar system, we generate long streams of 1000 near-transform-limited single photons with high mutual indistinguishability. The Hong-Ou-Mandel interference of two photons is measured as a function of their emission time separation varying from 13 ns to 14.7 μs, where the visibility slightly drops from 95.9(2)% to a plateau of 92.1(5)% through a slow dephasing process occurring at a time scale of 0.7 μs. A temporal and spectral analysis reveals the pulsed resonance fluorescence single photons are close to the transform limit, which are readily useful for multiphoton entanglement and interferometry experiments.

Hui Wang;Z. C. Duan;Y. H. Li;Si Chen;J. P. Li;Y. M. He;M. C. Chen;Yu He;X. Ding;承志 彭;Christian Schneider;Martin Kamp;Sven Höfling;Chao Yang Lu;建伟 潘

Physical Review Letters

2016-5-27

We experimentally entangle freely propagating particles that never physically interacted with one another or which have never been dynamically coupled by any other means. This demonstrates that quantum entanglement requires the entangled particles neither to come from a common source nor to have interacted in the past. In our experiment we take two pairs of polarization entangled photons and subject one photon from each pair to a Bell-state measurement. This results in projecting the other two outgoing photons into an entangled state.

建伟 潘;Dik Bouwmeester;Harald Weinfurter;Anton Zeilinger

Physical Review Letters

1998

We experimentally demonstrate active three-dimensional (3D) imaging at a range of up to 21.6 km in daylight by constructing a high-efficiency single-photon LiDAR system and developing a long-range-tailored computational algorithm.

Zheng Ping Li;Xin Huang;Yuan Cao;Bin Wang;Yu Huai Li;Jun Zhang;Qiang Zhang;承志 彭;Feihu Xu;建伟 潘

2019-5

建伟 潘

2009