Subjects: Optics >> Quantum optics submitted time 2023-07-10
Abstract： The atomic system has reflection symmetry, parity, and atomic stimulated radiation amplified by a parallel plane resonant cavity, can generate macroscopic photons entangled state[4].
It is a quantum entangled state of 2N photons with a certain parity, a total momentum of zero, a certain energy, and a certain angular momentum. Observing it in time and space has uncertainty and randomness. According to the Heisenberg uncertainty principle, its energy (frequency) and momentum are completely determined. The measurement accuracy can reach the Heisenberg quantum limit and has a quantum 2N enhancement effect (2N is the number of entangled photons).
The probability distribution P2N （t） of ∣Ф2NI > and its fourier transform P2N （w-w0 ）were measured through experiments, and the experimental results were in line with theoretical expectations. And the lifetime of macroscopic photons entangled state was observed, which also has a 2N enhancement factor. The experimental results are consistent with theoretical expectations.
Peer Review Status:
Awaiting Review
Subjects: Optics >> Quantum optics submitted time 2023-06-25
Abstract： Multi-photon entanglement is the core technology of quantum information technology such as quantum computation and quantum communication. Two-photon entanglement generated by spontaneous parametric down-conversion is a commonly used source of entanglement. Entangled photons emit randomly, and the probability of entanglement pairs is very small. Although great achievements have been made, it is still far from the application requirements of quantum computing and other fields. New approaches need to be explored from two aspects of basic theory and experimental research.
In this paper, the fundamental process of stimulated radiation and the mechanism of stimulated radiation are studied. It is found that the quantum properties of the initial two-photon state produced by this process are closely related to the symmetry of the stimulated substances. If the electronic states of stimulated radiation substances have parity, their wave functions also have parity, such as atoms, molecules with symmetric centers, crystals with reflection symmetry, etc. The electronic states of these substances have parity and reflection symmetry. The stimulated radiation process of a parity substances obeys parity conservation. The two-photon state produced by the stimulated radiation has parity and is superposition entangled state. Such two entangled photons pass through the action of parallel plane resonator, and then through stimulated radiation, the process is repeated again and again, and finally produces multi-photon entanglement.
The main results and conclusions of this paper are as follows: multi-photon entangled state is generated by stimulated radiation of parity substances. If the electronic state of the laser substance has parity, the multi-photon state produced by the stimulated radiation in the laser resonator (parallel plane cavity) is entangled state and can be output from a symmetrical two-way single longitudinal mode laser.
The expression of multiphoton entanglement is given theoretically. A symmetrical bi-directional output single longitudinal mode He-Ne laser has been developed. The experimental verification of multi-photon entangled state has been carried out. The experimental results are in good agreement with the theoretical expectations.
Peer Review Status:Awaiting Review
Subjects: Optics >> Quantum optics submitted time 2023-02-25
Yaqing Jin
Ye Yang
Huibo Hong
Xiao Xiang
Runai Quan
Tao Liu
Ninghua Zhu
Ming Li
Ruifang Dong
Shougang Zhang
Abstract： With energy-time entangled biphoton sources as the optical carrier and time-correlated single-photon detection for high-speed radio frequency (RF) signal recovery, the method of quantum microwave photonics (QMWP) has presented the unprecedented potential of nonlocal RF signal encoding and efficient RF signal distilling from the dispersion interference associated with ultrashort pulse carriers. In this letter, its capability in microwave signal processing and prospective superiority is further demonstrated. Both the QMWP RF phase shifting and transversal filtering functionality, which are the fundamental building blocks of microwave signal processing, are realized. Besides the perfect immunity to the dispersion-induced frequency fading effect associated with the broadband carrier in classical microwave photonics, a native two-dimensional parallel microwave signal processor is provided. These demonstrations fully prove the superiority of QMWP over classical MWP and open the door to new application fields of MWP involving encrypted processing.
Peer Review Status:Awaiting Review
Subjects: Optics >> Quantum optics submitted time 2023-02-25
Abstract： We study the open XXZ spin chain with a PT-symmetric non-Hermitian boundary field. We find an interaction-induced scale-free non-Hermitian skin effect by using the coordinate Bethe ansatz. The steady state and the ground state in the PT broken phase are constructed, and the formulas of their eigen-energies in the thermodynamic limit are obtained. The differences between the many-body scale-free states and the boundary string states are explored, and the transition between the two at isotropic point is investigated. We also discuss an experimental scheme to verify our results.
Peer Review Status:Awaiting Review
Subjects: Optics >> Quantum optics submitted time 2023-02-25
Abstract： Coherent interactions between quantum emitters in tailored photonic structures is a fundamental building block for future quantum technologies, but remains challenging to observe in complex solid-state environments, where the role of decoherence must be considered. Here, we investigate the optical interaction between two quantum emitters mediated by one-dimensional waveguides in a realistic solid-state environment, focusing on the creation, population and detection of a sub-radiant state, in the presence of dephasing. We show that as dephasing increases, the signatures of sub-radiance quickly vanish in intensity measurements yet remain pronounced in photon correlation measurements, particularly when the two emitters are pumped separately so as to populate the sub-radiant state efficiently. The applied Green's tensor approach is used to model a photonic crystal waveguide, including the dependence on the spatial position of the integrated emitter. The work lays out a route to the experimental realization of sub-radiant states in nanophotonic waveguides containing solid-state emitters.
Peer Review Status:Awaiting Review
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