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Optimizing the choice of spin-squeezed states for detecting and characterizing quantum processes [electronic resource].

Published:
Washington, D.C. : United States. Dept. of Energy, 2014.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description:
Article numbers 041,025 : digital, PDF file
Additional Creators:
Sandia National Laboratories, United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary:
Quantum metrology uses quantum states with no classical counterpart to measure a physical quantity with extraordinary sensitivity or precision. Most such schemes characterize a dynamical process by probing it with a specially designed quantum state. The success of such a scheme usually relies on the process belonging to a particular one-parameter family. If this assumption is violated, or if the goal is to measure more than one parameter, a different quantum state may perform better. In the most extreme case, we know nothing about the process and wish to learn everything. This requires quantum process tomography, which demands an informationally complete set of probe states. It is very convenient if this set is group covariant—i.e., each element is generated by applying an element of the quantum system’s natural symmetry group to a single fixed fiducial state. In this paper, we consider metrology with 2-photon (“biphoton”) states and report experimental studies of different states’ sensitivity to small, unknown collective SU(2) rotations [“SU(2) jitter”]. Maximally entangled N00N states are the most sensitive detectors of such a rotation, yet they are also among the worst at fully characterizing an a priori unknown process. We identify (and confirm experimentally) the best SU(2)-covariant set for process tomography; these states are all less entangled than the N00N state, and are characterized by the fact that they form a 2-design.
Report Numbers:
E 1.99:1214237
Subject(s):
Note:
Published through SciTech Connect.
11/07/2014.
Physical Review. X 4 4 ISSN 2160-3308; PRXHAE AM
Rozema, Lee; Mahler, Dylan; Blume-Kohout, Robin; Steinberg, Aephraim.
Funding Information:
AC04-94AL85000
View MARC record | catkey: 23503779