 Ph.D., Harvard University, 2005
 B.S.E., Electrical Engineering, Princeton University, 2000
Professor of Electrical and Computer Engineering
Associated Faculty in Physics
Fellow in the Princeton Center for Theoretical Science
Quantum mechanics has played an everincreasing 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 lowtemperature 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 onchip microwave resonator; the qubit can absorb and reemit 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 nonlinear 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, largescale 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.
Second, we study quantum and nonlinear 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, nonlinearities 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 nonlinear at powers where quantization is important?

AJ Kollár, M Fitzpatrick, AA Houck, “Hyperbolic lattices in circuit quantum electrodynamics,” Nature 571, 45 (2019)

T. M. Hazard, A. Gyenis, A. Di Paolo, A. T. Asfaw, S. A. Lyon, A. Blais, A. A. Houck, “Nanowire Superinductance Fluxonium Qubit,” Phys. Rev. Lett. 122, 010504 (2019)

G. Zhang, Yanbing Liu, J. J. Raftery, A. A. Houck, “Suppression of photon shot noise dephasing in a tunable coupling superconducting qubit,” Nature Partner Journal – Quantum Information, 3, 1 (2017)

M. Fitzpatrick, N. M. Sundaresan, A. C. Y. Li, Jens Koch, A. A. Houck, “Observation of a dissipative phase transition in a onedimensional circuit QED lattice,” Phys. Rev. X 7, 011016 (2017)

Yanbing Liu and A. A. Houck, “Quantum electrodynamics near a photonic bandgap,” Nature Physics, 13, 4852 (2016).
Honors and Awards:
 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, runnerup, Breakthrough of the Year (2003)
 Hertz Fellowship (20002005)
 Valedictorian, Princeton University, Class of 2000