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Seminar
FIELD Comp.Sciences:Information Science
DATE June 14 (Fri), 2019
TIME 10:00-11:00
PLACE 8101
SPEAKER Thomas B. Bahder
HOST Kim, Jaewan
INSTITUTE Army Research Office, Tokyo
TITLE Topological Quantum Sensors?
ABSTRACT From year 2005 to 2007, the Army Research Laboratory (ARL) had a research program in quantum sensors. During that time, Bahder (ARL) and Lopata (NRC postdoc) defined a quantum sensor as a quantum channel of information, with Shannon mutual information as a metric for the quality of the sensor [1].
In this talk, I will review the basic theory of a "conventional" quantum sensor, as was worked out at ARL during 2005. Later, Bahder worked on a theory of non-ideal quantum sensors, which are more relevant to experiments. In non-ideal quantum sensors, the initially prepared quantum state may have errors, there may be scattering (decoherence and dispersion) in the sensor, and output state detectors are not ideal [2,3].
I will then introduce simple 1-qubit and 2-qubit models of a quantum sensor that have an analogy with topological energy band theory [4]. I will review some topological concepts such as Berry curvature and the Quantum Geometric Tensor. Finally, I will speculate that there may be a new class of quantum sensors called "topological quantum sensors", or that topological ideas may be exploited in quantum sensors. I will give a detailed example of a simple quantum sensor of magnetic fields that exploits topological ideas and is based on the dynamical quantum Hall effect [5].
1. T. B. Bahder and P. A. Lopata, "Fidelity of quantum interferometers", Rev. A 74, 051801(R) (2006).
2. D. S. Simon, A. V. Sergienko, and T. B. Bahder, “Dispersion and fidelity in quantum interferometry”, Phys. Rev. A 78, 053829 (2008).
3. T. B. Bahder, “Phase estimation with nonunitary interferometers: Information as a metric’’, Phys. Rev. A 83, 053601 (2011).
4. A. Bansil, H. Lin, and T. Das, "Colloquium: Topological Band Theory", Rev. Mod. Phys. 88, 021004 (2016).
5. V. Gritsev and A. Polkovnikov, PNAS (Proceedings of the National Academy of Sciences U. S.) 109, 6457 (2012).
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