Multi-bit quantum random number generation by measuring positions of arrival photons

We report upon the realization of a novel multi-bit optical quantum random number generator by continuously measuring the arrival positions of photon emitted from a LED using MCP-based WSA photon counting imaging detector. A spatial encoding method is proposed to extract multi-bits random number from the position coordinates of each detected photon. The randomness of bits sequence relies on the intrinsic randomness of the quantum physical processes of photonic emission and subsequent photoelectric conversion. A prototype has been built and the random bit generation rate could reach 8 Mbit/s, with random bit generation efficiency of 16 bits per detected photon. FPGA implementation of Huffman coding is proposed to reduce the bias of raw extracted random bits. The random numbers passed all tests for physical random number generator. (C) 2014 AIP Publishing LLC

Entanglement generation under feedback control in dispersive regime

The entanglement generation in a system of two atoms dispersively coupled to a damped cavity mode and driven by a classical field is investigated by using the quantum-jump-based feedback control. We demonstrate that the entanglement of the two atoms can be significantly enhanced and a steady state of antisymmetric Bell state can be obtained. We focus on the role of classical driving, and verify that the laser driving results in a global steady state which can be reached in the whole atomic subspace, but it can only be reached from some special initial states without laser driving. Therefore the system with classical driving is more robust against spontaneous emission and non-unit detection efficiency. Numerical results demonstrate that the maximal entanglement can be obtained for a wide range of parameters

Optomechanically Induced Transparency and Slow–Fast Light Effect in Hybrid Cavity Optomechanical Systems

We theoretically investigate the optomechanically induced transparency (OMIT) phenomenon and the fast and slow light effects of a four-mode optomechanical system with the Kerr medium. The optomechanical system is composed of an array of three single-mode cavities and a mechanical oscillator. The three cavities are a passive cavity, a no-loss-gain cavity and a gain optical cavity, respectively. A Kerr medium is inserted in the passive cavity. We study the influence of the Kerr medium on the stability of the optomechanical system, and find that the stable regime of the optomechanical system can be adjusted by changing the Kerr coefficient. We demonstrate that the phenomenon of optomechanically induced transparency will appear when the Kerr medium exists in the optomechanical system and find that the frequency position of the absorption peak on the left increases linearly with the Kerr coefficient. In addition, we also investigate the fast and slow light effects in this system. The results show that we can control the fast and slow light by adjusting the Kerr coefficient, tunneling strength, and driving field strength. This study has potential application prospects in the fields of quantum optical devices and quantum information processing

Hierarchically Porous, Superhydrophobic PLLA/Copper Composite Fibrous Membranes for Air Filtration

Epidemics such as pulmonary tuberculosis and pertussis can spread quickly through the air in enclosed or small spaces. Most of these diseases are caused by various bacteria. In hospitals, nursing homes, and biology laboratories, the requirement for air quality is often high. Particulate air filters can remove infectious bacteria from the air, making them a good choice for local ventilation systems to capture and remove bacteria or other pathogenic microbes. With high surface area, electrospun poly(l-lactic acid) (PLLA) fibrous membranes have the ability to capture small particles like bacteria. Moreover, copper has significant antimicrobial properties. In this Letter, we present a hierarchically porous PLLA membrane created through electrospinning and acetone treatment. Additionally, we describe two methods for loading copper particles onto the hierarchically porous PLLA membrane, thereby providing capabilities for capturing and killing bacteria. The experiments demonstrated that the final PLLA/Cu composite fibrous membranes exhibit not only excellent air permeability but also remarkable antimicrobial performance while maintaining bendability and superhydrophobic ability. This study provides a simple process, low energy cost, and environmentally friendly method to produce the copper-coated PLLA membrane, which is especially suitable for potential applications in high-flux filtration equipment in hospitals, nursing homes, and biology laboratories

Hierarchically Porous, Superhydrophobic PLLA/Copper Composite Fibrous Membranes for Air Filtration

Epidemics such as pulmonary tuberculosis and pertussis can spread quickly through the air in enclosed or small spaces. Most of these diseases are caused by various bacteria. In hospitals, nursing homes, and biology laboratories, the requirement for air quality is often high. Particulate air filters can remove infectious bacteria from the air, making them a good choice for local ventilation systems to capture and remove bacteria or other pathogenic microbes. With high surface area, electrospun poly(l-lactic acid) (PLLA) fibrous membranes have the ability to capture small particles like bacteria. Moreover, copper has significant antimicrobial properties. In this Letter, we present a hierarchically porous PLLA membrane created through electrospinning and acetone treatment. Additionally, we describe two methods for loading copper particles onto the hierarchically porous PLLA membrane, thereby providing capabilities for capturing and killing bacteria. The experiments demonstrated that the final PLLA/Cu composite fibrous membranes exhibit not only excellent air permeability but also remarkable antimicrobial performance while maintaining bendability and superhydrophobic ability. This study provides a simple process, low energy cost, and environmentally friendly method to produce the copper-coated PLLA membrane, which is especially suitable for potential applications in high-flux filtration equipment in hospitals, nursing homes, and biology laboratories