Bulletin of the American Physical Society
APS March Meeting 2010
Volume 55, Number 2
Monday–Friday, March 15–19, 2010; Portland, Oregon
Session Y3: Two-particle Entanglement with Single Particle Emitters |
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Sponsoring Units: DCMP Chair: Janine Splettstoesser, Institute for Theoretical Physics A, RWTH Aachen, and Peter Samuelsson, Lund University Room: Oregon Ballroom 203 |
Friday, March 19, 2010 8:00AM - 8:36AM |
Y3.00001: Entanglement in a fermionic two-particle interferometer Invited Speaker: We discuss a theory for entanglement generation and detection in fermionic two-particle interferometers. The motivation for our work is provided by the recent experiment by the Heiblum group, Neder {\it et al}, Nature {\bf 448}, 333 (2007), realizing the two particle interferometer proposed in [1]. The experiment displayed a clear two-particle Aharonov-Bohm effect, however with an amplitude suppressed due to finite temperature and dephasing. This raised qualitative as well quantitative questions about entanglement production and detection in mesoscopic conductors at finite temperature. As a response to these questions, in our recent work [2] we present a general theory for finite temperature entanglement in mesoscopic conductors. Applied to the two-particle interferometer we show that the emitted two-particle state in the experiment is clearly entangled. \\[4pt] [1] Samuelsson, Sukhorukov, and Buttiker, Phys. Rev. Lett. {\bf 92}, 026805 (2004).\\[0pt] [2] Samuelsson, Neder, and Buttiker, Phys. Rev. Lett. {\bf 102}, 106804 (2009). [Preview Abstract] |
Friday, March 19, 2010 8:36AM - 9:12AM |
Y3.00002: Interference between two indistinguishable electrons - observation of two-particle Aharonov-Bohm interference Invited Speaker: The two-particle AB experiment proposed by Yurke et. al. [1] and Samuelsson et. al. [2], was realized recently in a mesoscopic device in the quantum Hall effect regime. It was the first observation of quantum interference oscillations between two independent non-interacting particles. The interference fringes were observed only in the joint probability of electrons arrival at two different drains; hence being the quantum analogue to the Hanbury Brown and Twiss experiment with classical waves [3]. This counter intuitive effect is a direct result of the quantum exchange statistics of identical quantum particles. The experimental details and results will be discussed in the light of the theoretical effort to interpret this observation as a signature of orbital entanglement between the two independent electrons, even tough they never interacted with each other. New difficulties regarding the finite temperature and imperfect visibility were resolved only recently, in a non- trivial way. \\[4pt] [1] B. Yurke D. Stoler, Phys. Rev. A46, 2229-2234 (1992) \\[0pt] [2] P. Samuelsson, E. V. Sukhorukov, M. Buttiker, Phys. Rev. Lett. 92, 02685 (2004). \\[0pt] [3] R. Hanbury Brown, R. Q. Twiss, Phil. Mag. 45, 663-682 (1954). [Preview Abstract] |
Friday, March 19, 2010 9:12AM - 9:48AM |
Y3.00003: Electron pumping at gigahertz frequencies Invited Speaker: Recently, we have overcome the upper frequency limit measured for earlier pumps, by removing the reliance on quantum mechanical tunnelling through barriers on either side of a quantum dot [1]. The ease of operation, high frequency and simplicity of the waveform driving the pump were unexpected findings, contrary to previous predictions. The high speed (GHz), accurate pumping of electrons at the nano-Amp current level allows for easy integration in a wide range of applications from the development of the current standard in the field of metrology to single photon production and quantum based computing, making these new findings of value to many scientific disciplines. The inclusion of a perpendicular magnetic field [2] has shown a marked improvement in the accuracy of the pumped current and allows the study of the interactions of controlled dynamic electrons with a magnet field. Recent work combining two electron pumps in parallel [3] has demonstrated an increase in current output without the increase in error associated with a higher output current from a single pump. With the control and manipulation of a selected number of electrons there is the possibility of the creation of a two-particle entangled state. An interference-type experiment with the inclusion of a beam splitter could be used to probe this state. \\[4pt] [1] M. D. Blumenthal, B. Kaestner, L. Li, S. Giblin, T. J. B. M. Janssen, M. Pepper, D. Anderson, G. Jones, and D. A. Ritchie, Nature Physics \textbf{3}, 343 (2007). \\[0pt] [2] S. J. Wright, M. D. Blumenthal, Godfrey Gumbs, A. L. Thorn, M. Pepper, T. J. B. M. Janssen, S. N. Holmes, D. Anderson, G. A. C. Jones, C. A. Nicoll, and D. A. Ritchie, Phys Rev B. \textbf{78}, 233311 (2008). \\[0pt] [3] S. J. Wright, M. D. Blumenthal, M. Pepper, D. Anderson, G. A. C. Jones, C. A. Nicoll, and D. A. Ritchie, Phys Rev B. \textbf{80}, 113303 (2009). [Preview Abstract] |
Friday, March 19, 2010 9:48AM - 10:24AM |
Y3.00004: Electron quantum optics: current and noise of a single electron emitter Invited Speaker: Ballistic electronic transport along the Quantum Hall edge states of two dimensional electron gases presents strong analogies with the propagation of photons which have been best illustrated by the realization of electronic Mach-Zehnder interferometers [1]. The analogy can be pushed to quantum optics where single electron emitters are realized to manipulate one or few charges. Celebrated experiments such as the one electron Hanbury-Brown and Twiss or the two electrons Hong-Ou-Mandel experiments can then be implemented [2]. This brings us closer to the on demand generation of entangled electron pairs. The feasibility of these new quantum optics experiments relies also on the ability to measure the output correlations of the current generated by the source. We will present the first realization of such a single electron source characterized both by the measurement of the average ac current [3] and its fluctuations. The source is made of a periodically driven mesoscopic capacitor [4,5] coupled to the electron reservoir by a tunnel barrier of adjustable transmission. At the first half period of the excitation drive, an occupied energy level of the dot is suddenly promoted above the Fermi energy and a single charge is emitted on the tunnelling escape time. In the second half period, the level is brought back to its initial value and an electron is absorbed, leaving a hole in the Fermi sea. Single electron emission appears as a quantization of the ac current in units of the electric charge times the drive frequency. The occurrence of spurious multiple charge events can be ruled out by the measurement of the noise presented here. Our measurements confirm single electron emission where the noise reduces to the quantum jitter associated with the Heisenberg uncertainty on the emission time.\\[4pt] [1] Y. Ji et al., Nature 422, 415 (2003) \\[0pt] [2] S. Ol'khovskaya et al., Phys. Rev. Lett. 101, 166802 (2008)\\[0pt] [3] G. F\`eve et al., Science 316, 1169 (2007) \\[0pt] [4] M. B\"{u}ttiker et al., Phys. Lett. A 180, 364 (1993)\\[0pt] [5] J. Gabelli et al., Science 313, 499 (2006) [Preview Abstract] |
Friday, March 19, 2010 10:24AM - 11:00AM |
Y3.00005: Two-Particle Nonlocal Aharonov-Bohm Effect from Two Single-Particle Emitters Invited Speaker: High-frequency single-particle emitters have been realized experimentally in the integer quantum Hall effect regime [1]: the particles are injected into edge states, operating as wave guides, and encounter splitters realized by quantum point contacts. These tools allow for the implementation of complex interferometers in mesoscopic systems showing two-particle interference effects. An example for tunable two-particle correlations is manifest in the electronic analogue of the Hong-Ou-Mandel interferometer [2], where a noise suppression is found due to the Pauli principle. In the work presented here we explore the entanglement production from two uncorrelated sources. We therefore propose a mesoscopic circuit in the quantum Hall effect regime comprising two independent single-particle sources and two distant Mach-Zehnder interferometers with magnetic fluxes. This and the tunability of the single-particle sources allow in a controllable way to produce orbitally entangled electrons [3]. Two-particle correlations appear as a consequence of erasing of which-path information due to collisions taking place at distant interferometers and in general at different times. While the current in this setup is insensitive to the magnetic flux, the two-particle correlations manifest themselves as an Aharonov-Bohm effect in the noise. In an appropriate time-interval the concurrence reaches a maximum and a Bell inequality is violated, proving the existence of time-bin entanglement.\\[4pt] [1] G. F\`eve, A. Mah\'e, J.-M. Berroir, T. Kontos, B. Pla\c{c}ais, D. C. Glattli, A. Cavanna, B. Etienne, and Y. Jin, Science 316, 1169 (2007).\\[0pt] [2] S. Ol'Khovskaya, J. Splettstoesser, M. Moskalets, and M. Buttiker, Phys. Rev. Lett. 101, 166802 (2008).\\[0pt] [3] J. Splettstoesser, M. Moskalets, and M. Buttiker, Phys. Rev. Lett.103, 076804 (2009). [Preview Abstract] |
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