Bulletin of the American Physical Society
2013 Joint Meeting of the APS Division of Atomic, Molecular & Optical Physics and the CAP Division of Atomic, Molecular & Optical Physics, Canada
Volume 58, Number 6
Monday–Friday, June 3–7, 2013; Quebec City, Canada
Session T5: Entanglement |
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Chair: Daniel Stack, US Army Research Lab Room: 301 |
Friday, June 7, 2013 8:00AM - 8:12AM |
T5.00001: $^{138}$Ba$^{+}$ Ion-Photon Entanglement using Ultrafast Pulses Carolyn Auchter, Tom Noel, Boris Blinov We present preliminary evidence of entanglement between the ground state of a trapped $^{138}$Ba$^{+}$ ion and the polarization state of the photons it spontaneously emits. The spontaneously emitted photons result from weak excitation by short ($\sim$40 ns) pulses of resonant CW laser light of the ions initially prepared in a single Zeeman ground state. This protocol is facilitated by the presence near the trap of an integrated electrode that allows ground state spin flips to be driven in under a microsecond. We also present our work toward improved entanglement fidelity by employing ultrafast pulses from a mode-locked Ti:Sapphire laser for ion excitation, with the ultimate goal of doing remote entanglement of barium ions in distant traps. Barium is a particularly good candidate for such research due to the relatively long wavelength of the transitions involved, which makes it suitable for fiber optic transmission over long distances. [Preview Abstract] |
Friday, June 7, 2013 8:12AM - 8:24AM |
T5.00002: Reliable Entanglement Verification Juan Miguel Arrazola, Oleg Gittsovich, John Matthew Donohue, Jonathan Lavoie, Kevin Resch, Norbert L\"utkenhaus Entanglement plays a central role in quantum protocols. It is therefore important to be able to verify the presence of entanglement in physical systems from experimental data. In the evaluation of these data, the proper treatment of statistical effects requires special attention, as one can never claim to have verified the presence of entanglement with certainty. Recently increased attention has been paid to the development of proper frameworks to pose and to answer these type of questions. In this work, we apply recent results by Christandl and Renner on reliable quantum state tomography to construct a reliable entanglement verification procedure based on the concept of confidence regions. The statements made do not require the specification of a prior distribution nor the assumption of an independent and identically distributed (i.i.d.) source of states. Moreover, we develop efficient numerical tools that are necessary to employ this approach in practice, rendering the procedure ready to be employed in current experiments. We demonstrate this fact by analyzing the data of an experiment where photonic entangled two-photon states were generated and whose entanglement is verified with the use of an accessible nonlinear witness. [Preview Abstract] |
Friday, June 7, 2013 8:24AM - 8:36AM |
T5.00003: Device-independent demonstration of genuine multipartite entanglement Julio T. Barreiro, Jean-Daniel Bancal, Philipp Schindler, Daniel Nigg, Markus Hennrich, Thomas Monz, Nicolas Gisin, Rainer Blatt Entanglement in a quantum system can be demonstrated experimentally by performing the measurements prescribed by an appropriate entanglement witness. However, the unavoidable mismatch between the implementation of measurements in practical devices and their precise theoretical modelling generally results in the undesired possibility of false-positive entanglement detection. Such scenarios can be avoided by using the recently developed device-independent entanglement witnesses (DIEWs) for genuine multipartite entanglement. Similarly to Bell inequalities, DIEWs only assume that consistent measurements are performed locally on each subsystem. No precise description of the measurement devices is required. We report a device-independent demonstration of genuine multipartite entanglement between up to six 40Ca+ ions. We also demonstrate genuine multipartite quantum nonlocality between up to six parties with the detection loophole closed. [Preview Abstract] |
Friday, June 7, 2013 8:36AM - 8:48AM |
T5.00004: Heralded entanglement between solid-state qubits separated by 3 meters Hannes Bernien, Bas Hensen, Wolfgang Pfaff, Gerwin Koolstra, Machiel Blok, Lucio Robledo, Tim Taminiau, Matthew Markham, Daniel Twitchen, Lilian Childress, Ronald Hanson Entanglement between spatially separated objects is one of the most intriguing phenomena in physics. Besides being of fundamental interest, entanglement is also a valuable resource in quantum information technology enabling secure quantum communication networks and distributed quantum computing. Here we present our recent results towards the realization of quantum networks with solid-state qubits. We have entangled two spin qubits in diamond, each associated with a nitrogen vacancy center [1]. The two diamonds reside in separate setups three meters apart. With no interaction between the two spins to mediate entanglement, we make use of a scheme based on quantum measurements: we perform a joint measurement on photons emitted by the NV centers that are entangled with the spins. The detection of the photons projects the spins into an entangled state. We verify the generated entanglement by single-shot readout of the spins in different bases. The entanglement reported here can in principle be combined with recently achieved initialization, readout and entanglement operations [2, 3] on local long-lived nuclear spin registers, enabling deterministic long-distance teleportation, quantum repeaters and extended quantum networks. [1] H. Bernien et al., submitted. [2] L. Robledo et al., Nature 477, 574 (2011). [3] W. Pfaff et al., Nature Physics 9, 29 (2013). [Preview Abstract] |
Friday, June 7, 2013 8:48AM - 9:00AM |
T5.00005: High Speed Heralded Entanglement of Remote Trapped Ion Qubits David Hucul, Susan Clark, Ismail Volkan Inlek, Christopher Monroe Large scale quantum information processing systems may require different types of quantum systems in separate quantum processing units connected via a reconfigurable quantum network. In order to carry out complex quantum algorithms on large numbers of qubits, it will become necessary to connect different quantum processing units at a rate faster than the qubit decoherence rate. Here we report on the use of high numerical aperture lenses to form heralded entangled trapped atomic ion spins through the interference of their emitted photons. We show that the solid angle of light collection need not degrade the entanglement fidelity. The use of NA = 0.6 lenses increases the entanglement rate by several orders of magnitude, which should surpass the observed spin coherence time of a single trapped atomic ion. Supported by the U.S. ARO, IARPA, the DARPA OLE program, and the MURI program; and the NSF Physics Frontier Center at JQI. [Preview Abstract] |
Friday, June 7, 2013 9:00AM - 9:12AM |
T5.00006: Dissipative generation of long range entanglement with Rydberg atoms Alex Carr, Mark Saffman We propose and analyze an approach for preparation of atomic spin singlet states using Rydberg mediated interactions and dissipation. Using asymmetric Rydberg interactions the two-atom Bell singlet is a dark state of the Rydberg pumping process. In a many spin setting anti-ferromagnetic states of nonlocal Ising models can be studied. Master equation simulations demonstrate Bell singlet preparation fidelity $F=0.999$ with only 3 MHz of Rydberg-Rydberg interaction strength. This implies that high fidelity entanglement can be created at distances beyond $20~\mu\rm m$, an order of magnitude greater than can be achieved with coherent Rydberg gates. Combining this approach with gate teleportation will allow for long distance gates in atomic qubit arrays. [Preview Abstract] |
Friday, June 7, 2013 9:12AM - 9:24AM |
T5.00007: Large-scale cluster entanglement in the quantum optical frequency comb: from linear chains to n-hypercubes Olivier Pfister, Pei Wang, Moran Chen, Matthew Pysher, Yoshichika Miwa, Russell Bloomer, Reihaneh Shahrokhshahi, Nicolas Menicucci Following our recent experimental demonstration of the continuous-variable entanglement of 60 resonant field modes (Qmodes) of a single optical parametric oscillator (OPO) into 15 independent quadripartite ``square'' cluster states, we present new theoretical and experimental developments that lead to considerable simplification of our previous proposal to implement large-scale continuous-variable cluster states in the quantum optical frequency comb (QOFC) of a single OPO. In particular, we will show how multiple hypercubic graph states can be experimentally generated in the QOFC of a few OPOs (as many as the hypercube's dimension), all of which are considerably simpler than in our previous proposals and experiments. We have found that the drastic need for tight boundaries of the entangled set of Qmodes no longer holds, as shown by a theoretical analysis of the errors on the cluster state caused by imperfect entangling interactions. [Preview Abstract] |
Friday, June 7, 2013 9:24AM - 9:36AM |
T5.00008: Local Detection of Quantum Correlations with a Trapped Ion Michael Ramm, Thaned Pruttivarasin, Manuel Gessner, Hartmut Haeffner Usually, detection of quantum correlations between two systems requires access to both of those systems. We present a method for detecting correlations between an open quantum system and its environment by acting only locally on the open system. Implementation of this method involves removing the correlations with a dephasing operation on the local system. By comparing the subsequent time evolution of the local system with and without the correlations, we are able to witness the correlations of the initial state. We can identify these correlations as quantum discord in the case of mixed states and entanglement for pure states. We discuss how this method can be implemented with trapped ions and present our experimental efforts towards this goal. [Preview Abstract] |
Friday, June 7, 2013 9:36AM - 9:48AM |
T5.00009: State-independent experimental test of quantum contextuality in an indivisible system Chong Zu, Yuexuan Wang, Dongling Deng, Xiuying Chang, Ke Liu, Panyu Hou, Haoxiang Yang, Luming Duan We report the first state-independent experimental test of quantum contextuality on a single photonic qutrit (three-dimensional system), based on a recent theoretical proposal [Phys. Rev. Lett. 108 030402 (2012)]. Our experiment spotlights quantum contextuality in its most basic form, in a way that is independent of either the state or the tensor product structure of the system. [Preview Abstract] |
Friday, June 7, 2013 9:48AM - 10:00AM |
T5.00010: Bell inequalities for general quantum observables Karl-Peter Marzlin, Thomas Osborn Bell inequalities provide an upper bound for the mean value of observables. They are fulfilled classical Hidden-Variable (HV) theories but are violated in quantum mechanics. Most Bell inequalities have been derived for observables with dichotomic spectra. We prove for general observables that the upper bound in HV theories can be expressed through a quantum mechanical expectation value. We present local and non-local examples of Bell inequality violation in quantum phase space. [Preview Abstract] |
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