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Experimental demonstration of memory-enhanced quantum communication 期刊论文
NATURE, 2020
作者:  Quinn, Robert A.;  Melnik, Alexey, V;  Vrbanac, Alison;  Fu, Ting;  Patras, Kathryn A.;  Christy, Mitchell P.;  Bodai, Zsolt;  Belda-Ferre, Pedro;  Tripathi, Anupriya;  Chung, Lawton K.;  Downes, Michael;  Welch, Ryan D.;  Quinn, Melissa;  Humphrey, Greg;  Panitchpakdi, Morgan;  Weldon, Kelly C.;  Aksenov, Alexander;  da Silva, Ricardo;  Avila-Pacheco, Julian;  Clish, Clary;  Bae, Sena;  Mallick, Himel;  Franzosa, Eric A.;  Lloyd-Price, Jason;  Bussell, Robert;  Thron, Taren;  Nelson, Andrew T.;  Wang, Mingxun;  Leszczynski, Eric;  Vargas, Fernando;  Gauglitz, Julia M.;  Meehan, Michael J.;  Gentry, Emily;  Arthur, Timothy D.;  Komor, Alexis C.;  Poulsen, Orit;  Boland, Brigid S.;  Chang, John T.;  Sandborn, William J.;  Lim, Meerana;  Garg, Neha;  Lumeng, Julie C.;  Xavier, Ramnik J.;  Kazmierczak, Barbara, I;  Jain, Ruchi;  Egan, Marie;  Rhee, Kyung E.;  Ferguson, David;  Raffatellu, Manuela;  Vlamakis, Hera;  Haddad, Gabriel G.;  Siegel, Dionicio;  Huttenhower, Curtis;  Mazmanian, Sarkis K.;  Evans, Ronald M.;  Nizet, Victor;  Knight, Rob;  Dorrestein, Pieter C.
收藏  |  浏览/下载:36/0  |  提交时间:2020/07/03

The ability to communicate quantum information over long distances is of central importance in quantum science and engineering(1). Although some applications of quantum communication such as secure quantum key distribution(2,3) are already being successfully deployed(4-7), their range is currently limited by photon losses and cannot be extended using straightforward measure-and-repeat strategies without compromising unconditional security(8). Alternatively, quantum repeaters(9), which utilize intermediate quantum memory nodes and error correction techniques, can extend the range of quantum channels. However, their implementation remains an outstanding challenge(10-16), requiring a combination of efficient and high-fidelity quantum memories, gate operations, and measurements. Here we use a single solid-state spin memory integrated in a nanophotonic diamond resonator(17-19) to implement asynchronous photonic Bell-state measurements, which are a key component of quantum repeaters. In a proof-of-principle experiment, we demonstrate high-fidelity operation that effectively enables quantum communication at a rate that surpasses the ideal loss-equivalent direct-transmission method while operating at megahertz clock speeds. These results represent a crucial step towards practical quantum repeaters and large-scale quantum networks(20,21).


A solid-state spin memory is used to demonstrate quantum repeater functionality, which has the potential to overcome photon losses involved in long-distance transmission of quantum information.


  
Current-driven magnetic domain-wall logic 期刊论文
NATURE, 2020, 579 (7798) : 214-+
作者:  Culp, Elizabeth J.;  Waglechner, Nicholas;  Wang, Wenliang;  Fiebig-Comyn, Aline A.;  Hsu, Yen-Pang;  Koteva, Kalinka;  Sychantha, David;  Coombes, Brian K.;  Van Nieuwenhze, Michael S.;  Brun, Yves, V;  Wright, Gerard D.
收藏  |  浏览/下载:31/0  |  提交时间:2020/07/03

Spin-based logic architectures provide nonvolatile data retention, near-zero leakage, and scalability, extending the technology roadmap beyond complementary metal-oxide-semiconductor logic(1-13). Architectures based on magnetic domain walls take advantage of the fast motion, high density, non-volatility and flexible design of domain walls to process and store information(1,3,14-16). Such schemes, however, rely on domain-wall manipulation and clocking using an external magnetic field, which limits their implementation in dense, large-scale chips. Here we demonstrate a method for performing all-electric logic operations and cascading using domain-wall racetracks. We exploit the chiral coupling between neighbouring magnetic domains induced by the interfacial Dzyaloshinskii-Moriya interaction(17-20), which promotes non-collinear spin alignment, to realize a domain-wall inverter, the essential basic building block in all implementations of Boolean logic. We then fabricate reconfigurable NAND and NOR logic gates, and perform operations with current-induced domain-wall motion. Finally, we cascade several NAND gates to build XOR and full adder gates, demonstrating electrical control of magnetic data and device interconnection in logic circuits. Our work provides a viable platform for scalable all-electric magnetic logic, paving the way for memory-in-logic applications.


  
Fast two-qubit logic with holes in germanium 期刊论文
NATURE, 2020, 577 (7791) : 487-+
作者:  Halpin-Healy, Tyler S.;  Klompe, Sanne E.;  Sternberg, Samuel H.;  Fernandez, Israel S.
收藏  |  浏览/下载:28/0  |  提交时间:2020/07/03

Universal quantum information processing requires the execution of single-qubit and two-qubit logic. Across all qubit realizations(1), spin qubits in quantum dots have great promise to become the central building block for quantum computation(2). Excellent quantum dot control can be achieved in gallium arsenide(3-5), and high-fidelity qubit rotations and two-qubit logic have been demonstrated in silicon(6-9), but universal quantum logic implemented with local control has yet to be demonstrated. Here we make this step by combining all of these desirable aspects using hole quantum dots in germanium. Good control over tunnel coupling and detuning is obtained by exploiting quantum wells with very low disorder, enabling operation at the charge symmetry point for increased qubit performance. Spin-orbit coupling obviates the need for microscopic elements close to each qubit and enables rapid qubit control with driving frequencies exceeding 100 MHz. We demonstrate a fast universal quantum gate set composed of single-qubit gates with a fidelity of 99.3 per cent and a gate time of 20 nanoseconds, and two-qubit logic operations executed within 75 nanoseconds. Planar germanium has thus matured within a year from a material that can host quantum dots to a platform enabling two-qubit logic, positioning itself as an excellent material for use in quantum information applications.


Spin qubits based on hole states in strained germanium could offer the most scalable platform for quantum computation.


  
China's Evolving Approach to "Integrated Strategic Deterrence" 科技报告
来源:Rand Corporation. 出版年: 2016
作者:  Michael S. Chase;  Arthur Chan
收藏  |  浏览/下载:5/0  |  提交时间:2019/04/05
United States  Information Operations  Cyber Warfare  China  Nuclear Deterrence  Space Warfare  
Assessing and Evaluating Department of Defense Efforts to Inform, Influence, and Persuade: Desk Reference 科技报告
来源:Rand Corporation. 出版年: 2015
作者:  Christopher Paul;  Jessica Yeats;  Colin P. Clarke;  Miriam Matthews
收藏  |  浏览/下载:5/0  |  提交时间:2019/04/05
Civil-Military Relations  Military Budgets and Defense Spending  Information Operations  Program Evaluation  Psychological Warfare  
Assessing and Evaluating Department of Defense Efforts to Inform, Influence, and Persuade: Handbook for Practitioners 科技报告
来源:Rand Corporation. 出版年: 2015
作者:  Christopher Paul;  Jessica Yeats;  Colin P. Clarke;  Miriam Matthews;  Lauren Skrabala
收藏  |  浏览/下载:7/0  |  提交时间:2019/04/05
Military Budgets and Defense Spending  Civil-Military Relations  Information Operations  Program Evaluation  Psychological Warfare  Students  
Assessing and Evaluating Department of Defense Efforts to Inform, Influence, and Persuade: An Annotated Reading List 科技报告
来源:Rand Corporation. 出版年: 2015
作者:  Christopher Paul;  Jessica Yeats;  Colin P. Clarke;  Miriam Matthews
收藏  |  浏览/下载:8/0  |  提交时间:2019/04/05
Military Budgets and Defense Spending  Civil-Military Relations  Information Operations  Program Evaluation  Psychological Warfare  Students  
Ensuring U.S. Air Force Operations During Cyber Attacks Against Combat Support Systems: Guidance for Where to Focus Mitigation Efforts 科技报告
来源:Rand Corporation. 出版年: 2015
作者:  Don Snyder;  George E. Hart;  Kristin F. Lynch;  John G. Drew
收藏  |  浏览/下载:6/0  |  提交时间:2019/04/05
Combat Support Operations  Cyber Warfare  Information Security  Information Operations  Netcentric Warfare  Military Information Technology Systems  
The Other Quiet Professionals: Lessons for Future Cyber Forces from the Evolution of Special Forces 科技报告
来源:Rand Corporation. 出版年: 2014
作者:  Christopher Paul;  Isaac R. Porche III;  Elliot Axelband
收藏  |  浏览/下载:10/0  |  提交时间:2019/04/05
Military Career Field Management  Cyber Warfare  Military Acquisition and Procurement  Military Information Technology Systems  Special Operations Forces