Nadav Katz

Racah Institute of Physics
Faculty of Science
The Hebrew University of Jerusalem, Jerusalem 91904, Israel
Tel: +972-2-6584133; Fax: +972-2-6586347
E-mail:katzn@phys.huji.ac.il
Website:http://www.phys.huji.ac.il/coherence/

Macroscopic quantum coherence lab

Our research focuses on macroscopic quantum coherence in solid state systems and atomic-optical systems. We study the coherence of Josephson junction superconducting circuits, which are a competitive implementation for quantum computing. The devices are fabricated with VLSI technology, and dedicated sputtering and oxidation unique to Josephson physics.

In recent years, it has come to the fore that the coherence of such devices is limited by complex surface physics and defect states in amorphous dielectrics within the circuit. Careful material science and characterization is key to producing further improvements.

Novel designs, which avoid these lossy materials have been implemented and we are actively pursuing ideas in these directions.

Fig 1: (a) Micrograph image of the coupled phase qubits. The coupling capacitor linking the two qubits is just below center. The shunting capacitor (white square), inductor (spiral) and state detection SQUIDs (loops with crosses on them) are clearly visible. The qubit junction, located near the shunting capacitor, is not visible on this scale. The image size is 1.38 X 1.1 mm. (b) Spectroscopy sweep of the qubit transition (a) and coherent swapping with resolved defects (b).

An additional area of activity is that of coherence in atomic systems - using multi-level spectroscopy we intend to create and manipulate long lived coherent states. A key technology is that of Electromagnetically Induced Transparency (EIT). We are actively building this aspect of the lab and expect first results by the end of the year.

Fig. 2: Left: Saturation absorption spectroscopy of the D2 line of Rubidium. The locked signal (over several hours - green trace in top right inset) is remarkably stable. Right: storage of light for over 100 microseconds, using the D1 line of Rubidium.

Fig. 3: Images of devices fabricated by myself and my group at the Hebrew University Nanocenter (Scale of left image ? 0.3 mm X 0.5 mm). This device contains a chain of Josephson Junction (~0.5 µm2 in area), bias circuitry, inductors and interdigitated capacitors, and on-chip SQUID readout. (right) 10 quarter wavelengths resonators driven by one common multiplexed coplanar line (die is 6mmX6mm in area). The devices on this chip reached quality factors of ~106 at the single photon excitation level

Specific research topics related to Nanoscience and Nanotechnology:

• Superconductivity at the nano-scale: We are building superconducting devices with nano-scopic constricting dimensions - that allow us to couple in microwave frequencies into atomic dimensions.
• Material research into dielectrics at ultra-low temperatures:  We are studying the loss tangents of dielectrics at ultra-low temperatures to find low loss materials for our devices. This information, surprisingly, does not exist for temperatures below 0.1 Kelvin.

List of publications in Nanoscience and Nanotechnology (2011-2012)

• "Controllable motion of optical vortex arrays using electromagnetically induced transparency", David Shwa, Evgeny Shtranvasser, Yoni Shalibo and Nadav Katz, accepted to Optics Express, (2012)
• "Increased Superconducting Transition Temperature of a Niobium Thin Film Proximity Coupled to Gold Nanoparticles Using Linking Organic Molecules", Katzir Eran; Yochelis Shira; Zeides Felix; et al., Phys. Rev. Lett. 108, 107004 (2012)
• "Sub-micrometer epitaxial Josephson junctions for quantum circuits", Kline Jeffrey S.; Vissers Michael R.; da Silva Fabio C. S.; et al., Superconductor Science and Technology 25, Issue 2 (2012)
• "Quantum and Classical Chirps in an Anharmonic Oscillator", Shalibo Yoni; Rofe Ya'ara; Barth Ido; et al., Phys. Rev. Lett. 108, 037701 (2012)
• "Strong coupling optimization with planar spiral resonators", Klein Avraham and Katz Nadav, Current Applied Physics 11, 1188 (2011)

Published articles resulting from cooperation between the universities

• "Increased Superconducting Transition Temperature of a Niobium Thin Film Proximity Coupled to Gold Nanoparticles Using Linking Organic Molecules", Katzir Eran; Yochelis Shira; Zeides Felix; et al., Phys. Rev. Lett. 108, 107004 (2012)
• "Sub-micrometer epitaxial Josephson junctions for quantum circuits", Kline Jeffrey S.; Vissers Michael R.; da Silva Fabio C. S.; et al., Superconductor Science and Technology 25, Issue 2 (2012)
• "Quantum and Classical Chirps in an Anharmonic Oscillator", Shalibo Yoni; Rofe Ya'ara; Barth Ido; et al., Phys. Rev. Lett. 108, 037701 (2012)

Significant publications in the last five years:

• "Reversal of the weak measurement of a quantum state in a superconducting phase qubit.", N. Katz, M. Neeley, M. Ansmann,Radoslaw C Bialczak, M. Hofheinz, Erik Lucero, A. O'Connell, H. Wang, A. Cleland, John M Martinis, Alexander N Korotkov, Phys. Rev. Lett. 101, 200401 (2008) [C-48, I-7.370].
• "Process tomography of quantum memory in a Josephson-phase qubit coupled to a two-level state", Matthew Neeley, M. Ansmann, Radoslaw C. Bialczak, M. Hofheinz, N. Katz, Erik Lucero, A. O'Connell, H. Wang, A. N. Cleland & John M. Martinis, Nature Physics 4, 523 (2008) [C-71, I-18.967].
• "Measurement of the entanglement of two superconducting qubits via state tomography", M. Steffen, M. Ansmann, Matthias Steffen, M. Ansmann, Radoslaw C. Bialczak, N. Katz, Erik Lucero, R. McDermott, Matthew Neeley, E. M. Weig, A .N. Cleland, and John M. Martinis, Science 313, Issue 5792, 1423-1425 (2006) [C-212, I-7.370].
• "Coherent State Evolution in a Superconducting Qubit from Partial-Collapse Measurement", N. Katz, M. Ansmann, Radoslaw C. Bialczak, Erik Lucero, R. McDermott, Matthew Neeley, Matthias Steffen, E. M. Weig, A. N. Cleland, John M. Martinis, and A. N. Korotkov, Science 312, 1498 (2006) [C-56, I-7.370].
• "Molecular Hydrogen formation on Astrophysically relevant surfaces", N. Katz, I. Furman, O. Biham, V. Pirronello & G. Vidali, ApJ, 522, 305 (1999) [C-189, I-7.370].

Cooperation with industries and defense projects (2011-2012):

Cooperation with other researchers/universities in Israel:

Research grants:

Students, postdocs and researchers:

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