scholarly journals A Method to Compute the Schrieffer–Wolff Generator for Analysis of Quantum Memory

Entropy ◽  
2021 ◽  
Vol 23 (10) ◽  
pp. 1260
Author(s):  
Dong Hwan Kim ◽  
Su-Yong Lee ◽  
Yonggi Jo ◽  
Duk Y. Kim ◽  
Zaeill Kim ◽  
...  
Keyword(s):  
Wide Class ◽  
Detection Rate ◽  
Quantum Memory ◽  
Noisy Environments ◽  
Long Distance ◽  
Microwave Cavities ◽  
Signal Mode ◽  
Microwave Regime ◽  
Recent Demonstration

Quantum illumination uses entangled light that consists of signal and idler modes to achieve higher detection rate of a low-reflective object in noisy environments. The best performance of quantum illumination can be achieved by measuring the returned signal mode together with the idler mode. Thus, it is necessary to prepare a quantum memory that can keep the idler mode ideal. To send a signal towards a long-distance target, entangled light in the microwave regime is used. There was a recent demonstration of a microwave quantum memory using microwave cavities coupled with a transmon qubit. We propose an ordering of bosonic operators to efficiently compute the Schrieffer–Wolff transformation generator to analyze the quantum memory. Our proposed method is applicable to a wide class of systems described by bosonic operators whose interaction part represents a definite number of transfer in quanta.

Towards long distance entanglement between a photon and a solid-state multimode quantum memory (Conference Presentation)

2020 ◽  
Author(s):  
Jelena Rakonjac ◽  
Dario Lago-Rivera ◽  
Samuele Grandi ◽  
Alessandro Seri ◽  
Hugues de Riedmatten
Keyword(s):  
Solid State ◽  
Quantum Memory ◽  
Long Distance

scholarly journals A hybrid quantum memory–enabled network at room temperature

2020 ◽  
Vol 6 (6) ◽  
pp. eaax1425
Author(s):  
Xiao-Ling Pang ◽  
Ai-Lin Yang ◽  
Jian-Peng Dou ◽  
Hang Li ◽  
Chao-Ni Zhang ◽  
...  
Keyword(s):  
High Speed ◽  
Information Technologies ◽  
Room Temperature ◽  
Schwarz Inequality ◽  
Quantum Memory ◽  
Atomic Ensemble ◽  
Single Photons ◽  
Long Distance ◽  
Atomic Excitations ◽  
A Chain

Quantum memory capable of storage and retrieval of flying photons on demand is crucial for developing quantum information technologies. However, the devices needed for long-distance links are different from those envisioned for local processing. We present the first hybrid quantum memory-enabled network by demonstrating the interconnection and simultaneous operation of two types of quantum memory: an atomic ensemble-based memory and an all-optical Loop memory. Interfacing the quantum memories at room temperature, we observe a well-preserved quantum correlation and a violation of Cauchy-Schwarz inequality. Furthermore, we demonstrate the creation and storage of a fully-operable heralded photon chain state that can achieve memory-built-in combining, swapping, splitting, tuning, and chopping single photons in a chain temporally. Such a quantum network allows atomic excitations to be generated, stored, and converted to broadband photons, which are then transferred to the next node, stored, and faithfully retrieved, all at high speed and in a programmable fashion.

scholarly journals One-hour coherent optical storage in an atomic frequency comb memory

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yu Ma ◽  
You-Zhi Ma ◽  
Zong-Quan Zhou ◽  
Chuan-Feng Li ◽  
Guang-Can Guo
Keyword(s):  
Optical Fibers ◽  
Large Scale ◽  
Quantum Communication ◽  
Frequency Comb ◽  
Quantum Memory ◽  
Spin Coherence ◽  
Quantum Repeater ◽  
Long Distance ◽  
Alternative Solutions ◽  
Atomic Frequency

AbstractPhoton loss in optical fibers prevents long-distance distribution of quantum information on the ground. Quantum repeater is proposed to overcome this problem, but the communication distance is still limited so far because of the system complexity of the quantum repeater scheme. Alternative solutions include transportable quantum memory and quantum-memory-equipped satellites, where long-lived optical quantum memories are the key components to realize global quantum communication. However, the longest storage time of the optical memories demonstrated so far is approximately 1 minute. Here, by employing a zero-first-order-Zeeman magnetic field and dynamical decoupling to protect the spin coherence in a solid, we demonstrate coherent storage of light in an atomic frequency comb memory over 1 hour, leading to a promising future for large-scale quantum communication based on long-lived solid-state quantum memories.

Nanophotonic rare-earth quantum memory with optically controlled retrieval

Science ◽  
2017 ◽  
Vol 357 (6358) ◽  
pp. 1392-1395 ◽  
Author(s):  
Tian Zhong ◽  
Jonathan M. Kindem ◽  
John G. Bartholomew ◽  
Jake Rochman ◽  
Ioana Craiciu ◽  
...  
Keyword(s):  
Frequency Comb ◽  
Essential Elements ◽  
Quantum Memory ◽  
High Fidelity ◽  
Long Distance ◽  
Quantum Networks ◽  
Network Nodes ◽  
Readout Time ◽  
On Chip ◽  
Photon Source

Optical quantum memories are essential elements in quantum networks for long-distance distribution of quantum entanglement. Scalable development of quantum network nodes requires on-chip qubit storage functionality with control of the readout time. We demonstrate a high-fidelity nanophotonic quantum memory based on a mesoscopic neodymium ensemble coupled to a photonic crystal cavity. The nanocavity enables >95% spin polarization for efficient initialization of the atomic frequency comb memory and time bin–selective readout through an enhanced optical Stark shift of the comb frequencies. Our solid-state memory is integrable with other chip-scale photon source and detector devices for multiplexed quantum and classical information processing at the network nodes.

scholarly journals Robust Placement of Water Quality Sensor for Long-Distance Water Transfer Projects Based on Multi-Objective Optimization and Uncertainty Analysis

2021 ◽  
Vol 13 (4) ◽  
pp. 1834
Author(s):  
Yu Li ◽  
Jinggang Chu ◽  
Guozhen Wei ◽  
Sifan Jin ◽  
Tiantian Yang ◽  
...  
Keyword(s):  
Water Quality ◽  
Detection Rate ◽  
Sensor Placement ◽  
Water Transfer ◽  
Water Diversion ◽  
Optimal Placement ◽  
Detection Accuracy ◽  
Detection Time ◽  
Long Distance ◽  
Water Quality Sensors

It is important to place water quality sensors along open channels in long-distance water transfer projects optimally for rapid source identification and efficient management of sudden water contamination. A new framework which considers multiple objectives, including earliest detection time, lowest missing detection rate and lowest sensor cost, and combines the randomness of injected contaminant type and contaminant incident consisting of contaminant intrusion location, time and mass, was established to obtain optimal placement of water quality sensor with better robustness in this paper. The middle route of the South-to-North Water Diversion Project in China was chosen as a case study, and it was found that both missing detection rate and detection time decrease with sensor cost gradually; furthermore, given the higher detecting precision, the detection accuracy and efficiency would be improved, a smaller number of water quality sensors would be needed, and the ten key placement positions where sensor with different detecting precision placed could be identified. Under the constraints of the allowable maximum missing detection rate, 1.00%, and detection time, 120.00 min, the detecting precision of 0.20 mg/L and 38 sensors placed could be selected as the optimal sensor placement scheme. Finally, with the consideration of contaminant uncertainty, the sensor placement scheme with better robustness could be constructed. The proposed framework would be helpful in solving the problem of water quality sensor placement with high practicality and efficiency in long-distance water transfer projects.

scholarly journals Long-distance quantum communication over noisy networks without long-time quantum memory

2014 ◽  
Vol 90 (6) ◽  
Author(s):  
Paweł Mazurek ◽  
Andrzej Grudka ◽  
Michał Horodecki ◽  
Paweł Horodecki ◽  
Justyna Łodyga ◽  
...  
Keyword(s):  
Quantum Communication ◽  
Quantum Memory ◽  
Long Distance ◽  
Time Quantum ◽  
Long Time

scholarly journals Entanglement distribution between quantum repeater nodes with an absorptive type memory

2020 ◽  
Vol 18 (05) ◽  
pp. 2050026
Author(s):  
Daisuke Yoshida ◽  
Kazuya Niizeki ◽  
Shuhei Tamura ◽  
Tomoyuki Horikiri
Keyword(s):  
State Of The Art ◽  
Frequency Comb ◽  
Quantum Memory ◽  
Nitrogen Vacancy ◽  
High Rate ◽  
Quantum Repeater ◽  
Long Distance ◽  
Nitrogen Vacancy Centers ◽  
Entanglement Distribution ◽  
Multimode Operation

Quantum repeaters, which are indispensable for long-distance quantum communication, are necessary for extending the entanglement from short distance to long distance; however, high-rate entanglement distribution, even between adjacent repeater nodes, has not been realized. In a recent work by [C. Jones et al., New J. Phys. 18 (2016) 083015], the entanglement distribution rate between adjacent repeater nodes was calculated for a plurality of quantum dots, nitrogen-vacancy centers in diamond, and trapped ions adopted as quantum memories inside the repeater nodes. Considering practical use, arranging a plurality of quantum memories becomes so difficult with the state-of-the art technology. It is desirable that high-rate entanglement distribution is realized with as few memory crystals as possible. Here, we propose new entanglement distribution scheme with one quantum memory based on the atomic frequency comb which enables temporal multimode operation with one crystal. The adopted absorptive-type quantum memory degrades the difficulty of multimode operation compared with the previously investigated quantum memories directly generating spin-photon entanglement. It is shown that this scheme improves the distribution rate by nearly two orders of magnitude compared with the result in [C. Jones et al., New J. Phys. 18 (2016) 083015] and the experimental implementation is close by utilizing state-of-the-art technology.

scholarly journals Studies on the readability and on the detection rate in a Mach–Zehnder interferometer-based implementation for high-rate, long-distance QKD protocols

2021 ◽  
Vol 75 (3) ◽  
Author(s):  
Christos Papapanos ◽  
Dimitris Zavitsanos ◽  
Adam Raptakis ◽  
Giannis Giannoulis ◽  
Christos Kouloumentas ◽  
...  
Keyword(s):  
Detection Rate ◽  
Zehnder Interferometer ◽  
High Rate ◽  
Long Distance ◽  
Mach Zehnder Interferometer
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