Bulletin of the American Physical Society
APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011; Dallas, Texas
Session L4: Quantum Information: Featured Experiments |
Hide Abstracts |
Sponsoring Units: GQI Chair: Richart Slusher, Georgia Tech Research Institute Room: Ballroom A4 |
Tuesday, March 22, 2011 2:30PM - 3:06PM |
L4.00001: Entanglement of spin waves among four quantum memories Invited Speaker: Quantum networks are composed of quantum nodes that interact coherently by way of quantum channels and open a broad frontier of scientific opportunities [1]. For example, a quantum network can serve as a `web' for connecting quantum processors for computation and communication as well as a ``simulator'' for enabling investigations of quantum critical phenomena arising from interactions among the nodes mediated by the channels. The physical realization of quantum networks generically requires dynamical systems capable of generating and storing entangled states among multiple quantum memories, and of efficiently transferring stored entanglement into quantum channels for distribution across the network. While such capabilities have been demonstrated for diverse bipartite systems, entangled states have so far not been achieved for interconnects capable of ``mapping'' multipartite entanglement stored in quantum memories to quantum channels. In my presentation, I will describe an experiment [2] that demonstrates measurement-induced entanglement stored in four atomic memories; user-controlled, coherent transfer of the atomic entanglement to four photonic channels; and characterization of the full quadripartite entanglement by way of quantum uncertainty relations [3]. Our work thereby provides an important advance for the distribution of multipartite entanglement across quantum networks. Moreover, our entanglement verification method can be applied for the study of entanglement order for condensed matter systems in thermal equilibrium. With regard to quantum measurement, our multipartite entangled state can be applied for sensing an atomic phase shift beyond the limit for any unentangled state. \\[4pt] [1] ``The Quantum Internet,'' H. J. Kimble, Nature \textbf{453}, 1023 (2008). \\[0pt] [2] K. S. Choi, A. Goban, S. Papp, S. J. van Enk and H. J. Kimble, Nature \textbf{468}, 412 (2010). \\[0pt] [3] S. B. Papp \textit{et al.}, Science \textbf{324}, 764 (2009). [Preview Abstract] |
Tuesday, March 22, 2011 3:06PM - 3:42PM |
L4.00002: Quantum Networks with Atoms and Photons Invited Speaker: Trapped atomic ions are among the most promising candidates for quantum information processing. All of the fundamental quantum operations have been demonstrated in this system, and the central challenge now is how to scale the system to larger numbers of qubits. By entangling atomic qubits through both deterministic phonon and probabilistic photon interfaces, the trapped ion system can be scaled in various ways for applications in quantum communication, quantum computing, and quantum simulations. I will discuss several options and issues for such atomic quantum networks, along with state-of-the-art experimental progress. [Preview Abstract] |
Tuesday, March 22, 2011 3:42PM - 4:18PM |
L4.00003: Quantum-logic clocks for fundamental physics and geodesy Invited Speaker: We have compared the rates of two quantum-logic clocks based on the optical $^1$S$_0$-$^3$P$_0$ transition in Al$^+$. The performance of the newer clock is unmatched, and despite many differences, their rates agree to $1.8 \pm 0.7 \times 10^{-17}$, within the accuracy limit of the older clock. The newer clock has an accuracy of $8.6 \times 10^{-18}$ and stability near $10^{-15} (\tau/s)^{-1/2}$. Quantum-correlation spectroscopy yields an improved measurement stability of $3.7\times10^{-16} (\tau/s)^{-1/2}$. This technique also allows Q-factors beyond $6\times10^{15}$ to be seen. This is the highest observed Q-factor in physics. The talk will discuss the basic operation of quantum-logic clocks based on Al$^+$, together with recent results that include a first geo-potential difference measurement, and constraints on the temporal variation of the fine-structure constant. Potential uses of entangled states in such clocks are also explored. [Preview Abstract] |
Tuesday, March 22, 2011 4:18PM - 4:54PM |
L4.00004: Towards Quantum Information Processing with Superconducting Circuits Invited Speaker: In the dozen years since the initial demonstrations that superconducting circuits based on Josephson junctions could be considered as qubits, there has been remarkable progress in the field. Several different ``species'' of these artificial atoms have been designed and tested, and coherence times have increased by more than 1,000, or a factor of 10 every three years. While real devices are still far from satisfying all the DiVincenzo criteria with fidelities that would meet the error correction threshold, one can nonetheless perform preparation, control, quantum logic, and measurement on multiple superconducting qubits, all with surprisingly high purity and precision given that these are man-made, solid-state systems. In recent years we have seen the preparation of highly-entangled multi-qubit states that violate the Bell and Mermin inequalities, as well as the demonstration of single quantum algorithms, which all benefit from the strong coupling, addressability, and all-electronic control that is possible with these systems. Many experiments employ the concept of a ``quantum bus,'' where qubits couple via superconducting transmission lines that form high-quality resonant cavities. A spinoff of this work is the advent of quantum optics on a chip: microwaves are photons too! The combination of qubits coupled to cavities has allowed the preparation and detection of single gigahertz photons, as well as other highly non-classical states of microwave light. Great progress has also been made in quantum measurement, and other Josephson circuits are now delivering amplifiers that operate at or beyond the Heisenberg limit. In this talk I will attempt to give an overview of some of the key concepts, some experimental highlights from recent years, and point out some possible directions for the future in this field. [Preview Abstract] |
Tuesday, March 22, 2011 4:54PM - 5:30PM |
L4.00005: Quantum Information and the Foundations of Quantum Mechanics: a story of mutual benefit Invited Speaker: Fundamental tests, particularly of quantum nonlocality, in the 1970s were crucial for the development of the new field of quantum information science. The consequent development of new technologies has led to novel possibilities to do fundamental tests. A most simple and clear test of noncontextuality, i.e. the existence of joint probability distributions, is due to a proposal by Klyachko et al. [PRL 101, 020403 (2008)]. There, the experimental tests became possible because of technology developed for quantum communication. It turns out that a very simple and intuitive picture of the contradiction with realism can be given. In parallel, an experiment closing the freedom of choice loophole in quantum entanglement [T. Scheidl et al., Proc Natl Acad Sci USA (2010) 19709], together with earlier experiments testing the Leggett-type inequality and objectivity, i.e. the existence of observables without the context of observation, might be challenged. Current micro-optics technology and the exploitation of external states of light like Hermite-Gauss and Laguerre-Gauss allows to extend this kind of experiments into higher-dimensional Hilbert Spaces. There, interesting connections between entanglement and mutually unbiased bases have been found. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700