We are an experimental research group that conducts research at the interface of Atomic, Molecular, and Optical (AMO) and condensed matter physics. We use nano-fabrication techniques to construct superconducting quantum circuits that allow us to probe fundamental questions in quantum mechanics.

Our research group is focused on understanding and controlling open quantum systems. These are quantum systems that necessarily interact with their environment, a process that can be deleterious to the quantum properties of the system, but can also be harnessed for control and to induce desired dynamics. In studying these systems, we hope to develop new ways of using precision quantum measurement to study novel phases of condensed matter, prepare quantum states, and probe chemical and biological systems.

Superconducting qubits are a promising system for the realization of quantum schemes for computation, simulation, and data encryption. While the fabrication of these systems allows for exquisite control over the properties of the quantum systems, their complex material nature results in coupling to uncontrolled degrees of freedom in the surrounding environment, eventually leading to decoherence of some states of these systems. Our research focuses on engineering the quantum system-environment interaction to preserve coherence, to prepare complex many body states, and to create interfaces with atomic systems such as cold neutral atoms, trapped ions, and solid state spins such as nitrogen vacancy centers in diamond.

(July 2018) Quantum Thermodynamics: A Quantum Maxwell's Demon

What happens when Maxwell's demon tries to sort molecules that are in a superposition of hot and slow at the same time? Read it in Phyiscal Review Letters or on the arXiv. You can read the press release: Demon in the details of quantum thermodynamics

(Feburary 2018) Kater is named one of the 2018 Cottrell Scholars by the Research Corporation for Scientific Advancement.

(Feburary 2018) CAREER: Heat, Work and Information in Quantum Circuits. Kater is awarded an NSF CAREER grant to explore quantum thermodynamics with superconducting qubits.
(November 2017) Quantum Metrology: Achieving optimal frequency sensitivity with a superconducting qubit through coherent control.

We experimentally demonstrate frequency sensitivity that scales as 1/T^2 using optimal control over a superconducting qubit. Read it in Phyiscal Review Letters or on the arXiv. You can read the press release: A bit of a 'quantum magic trick',

(June 2017) Quantum Zeno effects: How repeated measurement can either accelerate or slow the decay process.

Recent article by P. Harrington et al. is published in Phyiscal Review Letters and on the arXiv. You can read the press release: Shaking Schrodinger's Cat, or other media coverage: in The Week.

(April 2016) Mapping Quantum Trajectories in Spontaneous Emission:

Recent article by M. Naghiloo et al. is published in Nature Communications and on the arXiv.

(March 2016) State-signal Correlations: Exploring time symmetry in quantum measurement.

Recent Article by N. Foroozani et al. is published in PRL. Physical Review Letters 116 (2016) . arXiv.

(April 2015) Kater wins the Sloan Fellowship in Physics

Read the Washington University Press Release.

   (March 2015) The Past Quantum State: "Prediction and retrodiction for a continuously monitored superconducting qubit".

Recent Article by D. Tan et al. in Physical Review Letters.
How full measurement records reveal more information about the state of a quantum system than past alone. D. Tan et al, arxiv (2014)

Popular Coverage of the paper:
Washington University Record: "In the quantum world, the future affects the past" D. Lutz (Feb 2015)
Science News: "Quantum guessing game uses the future to predict the past", A. Grant, (Feb 2015)
International Business Times: "Time runs bizarre in quantum world where past is changed by the future", Jayalakshmi K, (Feb 2015)
Daily Mail: "Can the past be changed by the FUTURE?", E. Zolfagharifard, (Feb 2015)

  (July 2014) Nature Cover: "The Road Most Taken"

"Mapping the optimal route between two quantum states" by S. J. Weber, A. Chantasri, J. Dressel, A. N. Jordan, K. W. Murch, and I. Siddiqi.

Read it on arxiv or in Nature. Some press releases related to the paper:

Washington University in St. Louis: Finding Quantum Lines of Desire
UC Berkeley: Watching Schrodinger's Cat Die
University of Rochester: Mapping the Optimal Route between Two Quantum States
Nature: News & Views by Adrian Lupascu Quantum physics: The path most travelled
Huffington post: Robert Sanders
Live Science: Quantum Particles Take the Road Most Traveled

   (October 2013) Watching the wave function collapse: the Quantum Trajectories paper is published in Nature

Read the News and Views by Andrew Jordan, or the article on arstechnica.com. Or just read the Paper.