Speaker: Lorenza Viola (Dartmouth)

Title: When (quantum) noise is the signal: Highlights in qubit-based quantum spectral estimation

Abstract: Accurate characterization of the noise influencing a quantum system of interest has far-reaching implications across fundamental quantum science and device technologies, ranging from microscopic modeling of decoherence dynamics to noise-optimized quantum control. Thanks to their exquisite sensitivity to the surrounding environment, qubit systems can be naturally considered as “spectrometers”, or sensors, of their own noise. In this colloquium, I will explain how formalizing this intuition has led, over the past decade, to the development of quantum control techniques - collectively referred to as “quantum noise spectroscopy” -  for determining the noise spectral properties in a variety of realistic settings and qubit platforms. I will then highlight some of our contributions, by describing in particular how protocols inspired by “spin-locking relaxometry” from nuclear magnetic resonance may be exploited for characterizing correlated quantum noise in a two-qubit system, as experimentally demonstrated using a superconducting qubit circuit. I will conclude with an outlook on ongoing work and open problems in the field.

Short bio: Lorenza Viola is a theoretical physicist specializing in quantum information science. Following a “Laurea” (MS) degree in physics from the University of Trento, Italy, in 1991, and a Ph.D. in theoretical physics from the University of Padua, Italy, in 1996, she has been a postdoctoral fellow at the Massachusetts Institute of Technology until 2000 and then a J. R. Oppenheimer Fellow at Los Alamos National Laboratory. In 2004, she joined the Department of Physics and Astronomy at Dartmouth College, where she is now the James Frank Family Professor of Physics. Her research interests cover a range of topics within quantum information physics and quantum statistical mechanics — including methods for noise characterization and control in open quantum systems and quantum computation, quantum sensing and metrology, quantum phase transitions and topological phases of matter.  She is a board member of the International Physics and Control Society and is presently serving as a Divisional Associate Editor for Physical Review Letters. For her contributions, she has been elected a Fellow of the American Physical Society in 2014.