**Room:** B424 Engineering Quadrangle

**Phone:** 609-258-2571

**Email:** aahouck@princeton.edu

**Webpage:** Houck Lab: Quantum Computing and Condensed Matter Physics with Microwave Photons

- Ph.D., Harvard University, 2005
- B.S.E., Electrical Engineering, Princeton University, 2000

Quantum mechanics has played an ever-increasing role in electronics over the past several decades. At first, materials and devices were introduced that were designed with quantum mechanical principles, but still operated on classical information (for example, the silicon transistor). More recently, devices have been developed to store and manipulate quantum bits of information (qubits) towards quantum computing applications. Until the past few years, however, these qubits have only been addressed with classical light signals. A fully quantum mechanical circuit, in which quantum mechanical microwave signals address quantum bits, enables scalable quantum computing architectures and makes possible a full range of quantum optics experiments, all on a single chip in an integrated circuit. Our research focuses on these fully quantum mechanical integrated circuits, combining basic quantum mechanics, superconducting electronics, microwave circuits, quantum optics, and low-temperature measurement. The backbone of our work is a system known as circuit quantum electrodynamics (cQED). This system consists of a superconducting qubit coupled to an on-chip microwave resonator; the qubit can absorb and re-emit a single photon into the cavity hundreds of times before the photon is lost. This strong coupling opens the door to a vast array of experiments in quantum computing and non-linear optics. These are the two main thrusts of my research. First, my group is looking at ways of building a robust scalable quantum architecture. While small qubit systems have been developed and microwave cavities have been shown to make a good quantum bus connecting these qubits, large-scale quantum computers remain a distant goal. Quantum information is quite fragile, and individual qubits are currently plagued by information loss, called decoherence. Are there ways of building individual qubits that are robust to dominant noise sources? Even if perfect qubits could be achieved, new problems arise as circuits get more and more complicated. How can we wire up complex systems without destroying the individual parts? These are the types of quantum computing questions we address experimentally. My second main research area is the study of quantum and non-linear optics. Although people tend to think of lasers when they hear the term “optics,” the oscillating voltages and currents in a microwave circuit are also photons, and all principles of quantum optics apply to these devices as well. In fact, non-linearities can be much stronger in microwave devices, allowing us access to a very interesting regime of quantum optics. The goal of this area of research is to address the central question: What happens when a system is non-linear at powers where quantization is important?

- Presidential Early Career Award forScientists and Engineers (2010)
- NSF Early Career Award (2010)
- Packard Fellow (2009)
- Technology Review TR35 (2009)
- Sloan Research Fellowship (2009)
- Microsoft New Faculty Fellowship (Finalist 2009)
- Blavatnik Award for Young Scientists, NY Academy of Sciences (2008)
- Science Magazine, runner-up, Breakthrough of the Year (2003)
- Hertz Fellowship (2000-2005)
- Valedictorian, Princeton University, Class of 2000

L. S. Bishop, J. M. Chow, Jens Koch, A. A. Houck, M. H. Devoret, E. Thuneberg, S. M.Girvin, R. J. Schoelkopf, “Nonlinear response of the vacuum Rabi resonance,” Nature Physics, 5, 105 (2009).

L. S. Bishop, L. Tornberg, D. Price, E. Ginossar, A. Nunnenkamp, A. A. Houck, J. M. Gambetta, Jens Koch, G. Johansson, S. M. Girvin, R. J. Schoelkopf, “Proposal for generating and detecting multi-qubit GHZ states in circuit QED,” New J. Phys., 11, 073040 (2009);

A. A. Houck, Jens Koch, M. H. Devoret, S. M. Girvin, R. J. Schoelkopf, “Life after charge noise: recent results with transmon qubits,” Quant. Infor. Proc., 8, 105 (2009);

J. M. Chow, J. M. Gambetta, L. Tornberg, Jens Koch, Lev S. Bishop, A. A. Houck, B. R. Johnson, L. Frunzio, S. M. Girvin, R. J. Schoelkopf, “Randomized benchmarking and process tomography for gate errors in a solid-state qubit,” Phys. Rev. Lett., 102, 090502 (2009);

A. A. Houck, J. A. Schreier, B. R. Johnson, J. M. Chow, Jens Koch, J. M. Gambetta, D.I. Schuster, L. Frunzio, M.H. Devoret, S.M. Girvin, R.J. Schoelkopf, “Controlling the Spontaneous Emission Lifetime of a Superconducting Qubit,” Phys. Rev. Lett., 101, 080502 (2008);

J. A. Schreier, A. A. Houck, Jens Koch, D. I. Schuster, B. R. Johnson, J. M. Chow, J. M. Gambetta, J. Majer, L. Frunzio, M.H. Devoret, S.M. Girvin, R.J. Schoelkopf, “Suppressing Charge Noise Decoherence in Superconducting Charge Qubits,” Phys. Rev. B, 77, 180502(R) (2008);

J. Gambetta, A. Blais, M. Boissonneault, A. A. Houck, D. I. Schuster, S. M. Girvin, “Quantum Trajectory Approach to Circuit QED,” Phys. Rev. A, 77, 012112 (2008);

J. Majer, J. M. Chow, J. M. Gambetta, J. Koch, B. R. Johnson, J. A Schreier, L. Frunzio, D. I. Schuster, A. A. Houck, A. Wallraff, A. Blais, M. H. Devoret, S. M. Girvin, R. J. Schoelkopf, “Coupling Superconducting Qubits via a Cavity Bus”, Nature, 449, 443 (2007);

A.A. Houck, D.I. Schuster, J.M. Gambetta, J.A. Schreier, B. R. Johnson, J.M. Chow, J. Majer, L. Frunzio, M.H. Devoret, S.M. Girvin, R.J. Schoelkopf, “Generating Single Microwave Photons in a Circuit,” Nature, 449, 328 (2007);

J. Koch, T.M. Yu, J.M. Gambetta, A.A. Houck, D.I. Schuster, J. Majer, A. Blais, M.H. Devoret, S.M. Girvin, R.J. Schoelkopf, “Introducing the Transmon: a New Superconducting Qubit from Optimizing the Cooper Pair Box,” Phys. Rev. A, 76, 042319 (2007);

D.I. Schuster, A.A. Houck, J.A. Schreier, A. Wallraff, J.M. Gambetta, A. Blais, L. Frunzio, J. Majer, B. R. Johnson, M.H. Devoret, S.M. Girvin, R.J. Schoelkopf, “Resolving Photon Number States in a Superconducting Circuit,” Nature, 445, 515 (2007);

H.B. Heersche, Z. de Groot, J. A. Folk, L.P. Kouwenhoven, H. S. J. van der Zant, A. A. Houck, J. Labaziewicz, I. L. Chuang, Phys. Rev. Lett. 96, 017205 (2006);

A. A. Houck, J. Labaziewicz, E. K. Chan, J. A. Folk, I. L. Chuang, “Kondo Effect in Electromigrated Gold Break Junctions”, Nanoletters 5, 1685 (2005);

J. B. Brock, A. A. Houck, and I. L. Chuang, “Focusing Inside Negative Index Materials”, Appl. Phys. Lett. 85, 2472 (2004);

A. A. Houck, J. B. Brock and I. L. Chuang, "Experimental Observations of a Left-Handed Material that Obeys Snell's Law", Phys. Rev. Lett. 90, 137401 (2003) [cover]