Department of Condensed Matter

Amir Yacoby

  Email: amir.yacoby@weizmann.ac.il
  Title: Associate Professor
  Tel: +972-8-934-2399; Lab: +972-8-934-4468
  Fax: +972-8-934-4477
  Building: Braun
  Room: C204 		Amir Yacoby

 Research Interests:

  • Electrons confined to one dimension

    Electrons confined to 1D The behavior of electrons in a solid-state environment is often qualitatively modified from their vacuum properties due to Coulomb interaction. The low energy properties of such interacting systems are described in terms of dressed elementary excitations known as quasi-particles which interact only weakly among themselves. In two and three-dimensional disordered metals quasi-particles bear a strong resemblance to free electrons. They each carry a charge e and spin half and most importantly, their excitation spectrum, which for non-interacting electrons is simply determined by the underlying band mass m, is only slightly modified by the Coulomb interaction. However, the underlying quasi-particles in a one-dimensional metal, know as a Luttinger-liquid, are utterly different from free electrons. Here, for example, the spin and charge degrees of freedom completely decouple and can be separately excited. Using momentum and energy resolved tunneling between two closely situated parallel wires we have measured the collective excitation spectrum of electrons confined to one-dimension. At high electron densities, spin-charge separation is clearly observed. At low electron densities the system abruptly looses translation invariance and becomes localized. Our measurements indicate that the localization length corresponds to the inter-electron spacing.

    Relevant Publications

  • Local probes - Imaging localization and fractional charge

    Local probes In this work we address several outstanding questions pertaining to the microscopic properties of the fractional quantum Hall effect: What is the nature of the particles that participate in the localization but do not contribute to transport and can fractionally charged quasi particles localize in space? Using a scanning single electron transistor we image the individual localized states in the fractional quantum Hall regime and determine the charge of the localizing particles. Highlighting the symmetry between filling factors 1/3 and 2/3, our measurements show that fractionally charged quasi particles localize in space to sub-micron dimensions with e*=e/3, where e is the electron charge. Recently, at filling factors 2/3, we follow the behavior of the fractionally charged localized states through the spin phase transition.

    Relevant Publications



  • Coherent control and Manipulation of single electron spins

    Coherent control and Manipulation of single electron spins We demonstrate coherent control of a quantum two-level system based on two-electron spin states in a double quantum dot allowing state preparation, coherent manipulation, and projective read-out. These techniques are based on rapid electrical control of the exchange interaction. Separating and later recombining a singlet spin state provides a measurement of the spin dephasing time, T*2 ~ 10 ns, limited by hyperfine interactions with the GaAs host nuclei. Rabi oscillations of two-electron spin states are demonstrated, and spin-echo pulse sequences are used to suppress hyperfine-induced dephasing. Using these quantum control techniques, a coherence time for two-electron spin states exceeding 1 µs is observed.

    Relevant Publications



  • Molecular Transport

    Molecular Transport Electrical conduction through molecules depends critically on the delocalization of the molecular electronic orbitals and their connection to the metallic contacts. Thiolated (SH) conjugated organic molecules are therefore considered good candidates for molecular conductors. In such molecules, the orbitals are delocalized throughout the molecular backbone, with substantial weight on the sulphur–metal bonds. However, their relatively small size, typically ,1 nm, calls for innovative approaches to realize a functioning single-molecule device.

    We have developed a new approach for contacting a single molecule, and use it to study the effect of localizing groups within a conjugated molecule on the electrical conduction. Our method is based on synthesizing a dimer structure, consisting of two colloidal gold particles connected by a dithiolated short organic molecule, and electrostatically trapping it between two metal electrodes. We study the electrical conduction through three short organic molecules: 4,4’ -biphenyldithiol (BPD), a fully conjugated molecule; bis- (4-mercaptophenyl)-ether (BPE), in which the conjugation is broken at the centre by an oxygen atom; and 1,4- benzenedimethanethiol (BDMT), in which the conjugation is broken near the contacts by a methylene group. We find that the oxygen in BPE and the methylene groups in BDMT both suppress the electrical conduction relative to that in BPD.

    Relevant Publications

  • Quantum wires probe electrons.

     References (by topic):

    Electrons confined to one dimension

    Papers:

    • A. Yacoby, H. L. Stormer, N. S. Wingreen, K. W. Baldwin, L. N. Pfeiffer, and K. W. West, “Non universal conductance quantization in a quantum wire”, Phys. Rev. Lett. 77, 4612-4615 (1996).
    • A. Yacoby, H. L. Stormer, K. W. Baldwin, L. N. Pfeiffer, and K. W. West, “Magneto-Transport Spectroscopy on a Quantum Wire”, Solid State Communications 101, 77-81 (1997).
    • O. Auslaender, A. Yacoby, R. de Picciotto, K. W. Baldwin, L. N. Pfeiffer, and K. W. West, “Experimental Evidence for Resonant-Tunneling in a Luttinger Liquid”, Phys. Rev. Lett. 84, 1764-1767 (2000).
    • R. de Picciotto, H. L. Stormer, A. Yacoby, L, N. Pfeiffer, K. W. Baldwin, K. W. West, “2D-1D Coupling in Cleaved Edge Overgrowth”, Phys. Rev. Lett. 85, 1730-1733 (2000).
    • T. Kleimann, M. Sassetti, B. Kramer, A. Yacoby, “Charge and Spin Aaddition Eenergies of a One-Dimensional Quantum Dot”, Phys. Rev. B 62, 8144-8153 (2000).
    • O. Auslaender, A. Yacoby, R. de Picciotto, K. W. Baldwin, L. N. Pfeiffer, and K. W. West, “Tunneling Spectroscopy of the Elementary Excitations in a One-Dimensional Wire”, Science 295, 825-828 (2002).
    • Y. Tserkovnyak, B. I. Halperin, O. M. Auslaender, and A. Yacoby, “Finite Size Effects in Tunneling Between Parallel Quantum Wires”, Phys. Rev. Lett. 89, 136805 (2002).
    • Y. Tserkovnyak, B. I. Halperin, O. M. Auslaender, and A. Yacoby, “Interference and Zero Bias Anomaly in Tunneling between Luttinger Liquid Wires”, Phys. Rev. B. 68, 125312 (2003).
    • Y. Tserkovnyak, B. I. Halperin, O. Auslaender, A. Yacoby, “Signatures of Spin – Charge Separation in Double Wire Tunneling”, condmat/0312159.
    • O. Auslaender, H. Steinberg, A. Yacoby, Y. Tserkovnyak, B. I. Halperin, R. de Picciotto, K. W. Baldwin, L. N. Pfeiffer, and K. W. West, “Many-body dispersions in interacting ballistic quantum wires”, condmat/0405352.
    • M. J. Biercuk, N. Mason, J. Martin, A. Yacoby, C. M. Marcus, “Anomalous Conductance Quantization in Nanotubes”, Phys. Rev. Lett.94, 026801 (2005).
    • O. Auslaender, H. Steinberg, A. Yacoby, Y. Tserkovnyak, B. I. Halperin, K. W. Baldwin, L. N. Pfeiffer, and K. W. West, “Spin – Charge Separation and Localization in One-Dimension”, Science 308, 88 (2005).
    • H. Steinberg, O. Auslaender, A. Yacoby, J. Qian, G. A. Fiete, Y. Tserkovnyak, B. I. Halperin, K. W. Baldwin, L. N. Pfeiffer, and K. W. West,“Localization Transition in a Ballistic Quantum Wire“, condmat/0506812.
    Invited Conference Papers:

    Local probes - Imaging localization and fractional charge

    Papers:

    • A. Yacoby, H. F. Hess, T. A. Fulton, L. N. Pfeiffer, K. W. West, “Electrical Imaging of the Quantum Hall State”, Solid State Communications 111, 1-13 (1999).
    • S. Ilani, A. Yacoby, D. Mahalu, H. Shtrikman, “Unexpected behavior of the local compressibility near the B=0 metal-insulator transition”, Phys. Rev. Lett. 84, 3133-3136 (2000).
    • N. B. Zhitenev, T. A. Fulton, A. Yacoby, H. F. Hess, L. N. Pfeiffer, K. W. West. “Imaging of localized electronic states in the quantum Hall regime”, Nature 404, 473-476 (2000).
    • S. Ilani, A. Yacoby, D. Mahalu, H. Shtrikman, “Microscopic Structure of the Metal-Insulator Transition in Two Dimensions”, Science 292, 1354-1357 (2001).
    • S. Ilani, J. Martin, E. Tetelbaum, J. Smet, V. Umansky, D. Mahalu, A. Yacoby, “The Microscopic Nature of Localization in the Quantum Hall Effect”, Nature 427, 328 (2004).
    • J. Martin, S. Ilani, B. Verdene, J. Smet, V. Umansky, D. Mahalu, D. Schuh, G. Abstreiter, A. Yacoby, “Localization of Fractionally Charged Quasi Particles”, Science 305, 980 (2004).
    • A. Auerbach, I. Finkler, B. I. Halperin, and A. Yacoby, ”Steady – States of a Microwave – Irradiated Quantum – Hall Gas”, Phys. Rev. Lett. 94, 196801 (2005).
    Invited Conference Papers:

    Coherent control and Manipulation of single electron spins

    Papers:

    • C. W. J. Beenakker, M. Kindermann, C. M. Marcus, and A. Yacoby, “Entanglement Production in Chaotice Quantum Dots”, condmat/0310199.
    • J. R. Petta, A. C. Johnson, A. Yacoby, M. D. Lukin, C. M. Marcus, M. P. Hanson, A. C. Gossard, “Pulsed Gate Measurement of the Singlet – Triplet Relaxation Time in a Two – Electron Double Quantum Dot”, Phys. Rev. B 72, 161301 (2005).
    • J. M. Taylor, W. Dur, P. Zoller, A. Yacoby, C. M. Marcus, and M. D. Lukin, “Solid State Circuit for Spin Entanglement Generation and Purification”, Phys. Rev. Lett. 94, 236803 (2005).
    • J. R. Petta, A. C. Johnson, J. M. Taylor, E. A. Laird, A. Yacoby, M. D. Lukin, C. M. Marcus, M. P. Hanson, A. C. Gossard, “Coherent Manipulation of Coupled Electron Spins in Semiconductor Quantum Dots”, Science 309, 2180 (2005).
    • A. C. Johnson, J. R. Petta, J. M. Taylor, A. Yacoby, M. D. Lukin, C. M. Marcus, M. P. Hanson, A. C. Gossard, “Triplet – Singlet Spin Relaxation via Nuclei in a Double Quantum Dot”, Nature 435, 925 (2005).

    Molecular Transport

    Papers:

    • R. Krahne, A. Yacoby, H. Shtrikman, I. Bar-Joseph, Tali Dadosh, and J. Sperling, “Fabrication of Nano-Scale Gaps in Integrated Circuits”, Appl. Phys. Lett. 81, 730-732 (2002).
    • T. Dadosh, Y. Gordin, R. Krahne, I. Khivrich, D. Mahalu, V. Freydman, J. Sperling, A. Yacoby, I. Bar – Joseph, "Measurement of the Conductance of Single Conjugated Molecules", Nature 436, 677 (2005).

    Complete List of Publications

     Group Members:

    Research Associate: Dr. Jens Martin
    PhD Students: Hadar Steinberg
     Basile Verdene
     Yoav Gordin
     Tali Dadosh
     Merav Dolev
     Sandra Foletti
     Gilad Barak
    MSc Students: Nitzan Akerman
     Amit Finkler