### Olivier Pfister

*Ph.D., 1993, Paris-North*

*Professor*

*Experimental Atomic, Molecular, and Optical Physics,Experimental Quantum Information*

#### Research Interests

Olivier Pfister’s research focuses on experimental quantum optics and quantum information. The quantum nature of light (the existence of photons) is a fascinating subject which has turned into a mature experimental field since its inception in the eighties. The research by Pfister’s group, “Quantum Fields and Quantum Information” (QFQI), aims at blazing new trails into the realm of quantum information. In particular, QFQI and their theory collaborators, Nicolas Menicucci and Steven Flammia at the University of Sydney, discovered a new, highly scalable experimental paradigm for the implementation of quantum computing: building a quantum register out of the multitude of resonant fields (“Qmodes”) of a single optical cavity. The QFQI group and collaborators have achieved the preliminary step of “quantum computing over the optical frequency comb” (or “over the rainbow”...) by demonstrating, in the lab, the quantum correlations necessary for quantum computing, known as cluster-state entanglement, in 60 "qumodes," the continuous-variable analogue of qubits (quantum bits). This size is only bounded by current measurement limitations and Pfister and his group expect the actual size of the cluster state to be several thousands of qumodes. Work is now underway toward the creation of even larger cluster entangled states and their use for nontrivial quantum processing.

In addition to this work on continuous-variable entanglement, QFQI has also established a collaboration with the group of Dr. Sae Woo Nam at NIST toward the construction of a photon-number-resolved detector system which has been completed and installed in the QFQI lab. Using this unique machine, we have carried out quantum state tomography experiments and reconstructed the Wigner quasiprobability function of classical and nonclassical (Fock) states of light, We thus seek to attack the study of quantum fields from their purely particle aspect, as an epitome of the complementarity principle first put forth by Niels Bohr, and we are striving to understand the deep connections between the multipartite entanglement of continuous variables with that of discrete ones, as well as their interplay in hybrid application such as photon-added and subtracted squeezed states.

On the theoretical front, Pfister and Prof. Israel Klich have started a joint effort on the quantum simulation of condensed matter physics, and especially some of its intractable problems, using experimental quantum optics in the fullest sense, i.e., making full use of its undulatory and corpuscular nature.

Last but not least, the group has engaged in a collaboration with Profs. Joe Campbell and Andreas Beling in the Department of Electrical and Computer Engineering in the UVA School of Engineering and Applied Sciences. This work is centered on the design, fabrication, and characterization of cutting-edge photodetectors by Campbell and Beling, with utilization for quantum information applications in Pfister's group. Conversely, the question has been posed of whether the fundamental principal of quantum physics, such as Heisenberg inequalities, can be fully utilized to optimize detection design.

Professor Pfister's work has been funded continuously by NSF, and sporadically by DARPA, ARO, DoE, and the State of Virginia.

#### Graduate Students

#### Selected Publications

R. Nehra, A. Win, M. Eaton, N. Sridhar, R. Shahrokhshahi, Th. Gerrits, A. Lita, S. W. Nam, and O. Pfister, *State-independent quantum tomography by photon-number-resolving measurements*, Optica **6**, 1356 (2019).

J. Zang, Z. Yang, X. Xie, M. Ren, Y. Shen, Z. Carson, O. Pfister, A. Beling, and J. C. Campbell, *High quantum efficiency uni-traveling-carrier photodiode*, IEEE Photonics Technology Letters **29**, 302 (2017).

R. N. Alexander, P. Wang, N. Sridhar, M. Chen, O. Pfister, and N. C. Menicucci, *One-way quantum computing with arbitrarily large time-frequency continuous-variable cluster states from a single optical parametric oscillator*, Physical Review A **94**, 032327 (2016).

M. Chen, N.C. Menicucci, and O. Pfister, *Experimental realization of multipartite entanglement of 60 modes of a quantum optical frequency comb*, Physical Review Letters **112**, 120505 (2014).

M. Pysher, Y. Miwa, R. Shahrokhshahi, R. Bloomer, and O. Pfister, *Parallel generation of quadripartite cluster entanglement in the optical frequency comb*, Physical Review Letters **107**, 030505 (2011). Featured in Physics Today

R. Bloomer, M. Pysher, and O.Pfister, *Nonlocal restoration of two-mode squeezing in the presence of strong optical loss*, New Journal of Physics **13**, 063014 (2011).

N.C. Menicucci, S.T. Flammia, and O. Pfister, *One-way quantum computing in the optical frequency comb*, Physical Review Letters **101**, 130501 (2008). Spotlit in APS Physics and in Nature.

S. Feng and O. Pfister, *Quantum interference of ultrastable twin optical beams*, Physical Review Letters **92**, 203601 (2004).

#### News Items

#### Honors

**APS Fellow**[2013]

**UVA Distinguished Research Award**[2013]

**2nd Place, JILA Clever Idea Conest**[1996]